Class: Array
Relationships & Source Files | |
Super Chains via Extension / Inclusion / Inheritance | |
Instance Chain:
self,
::Enumerable
|
|
Inherits: | Object |
Defined in: | array.c, array.rb, pack.rb |
Overview
An Array
is an ordered, integer-indexed collection of objects, called elements. Any object (even another array) may be an array element, and an array can contain objects of different types.
Array
Indexes
Array
indexing starts at 0, as in C or Java.
A positive index is an offset from the first element:
-
Index 0 indicates the first element.
-
Index 1 indicates the second element.
-
…
A negative index is an offset, backwards, from the end of the array:
-
Index -1 indicates the last element.
-
Index -2 indicates the next-to-last element.
-
…
A non-negative index is in range if and only if it is smaller than the size of the array. For a 3-element array:
-
Indexes 0 through 2 are in range.
-
Index 3 is out of range.
A negative index is in range if and only if its absolute value is not larger than the size of the array. For a 3-element array:
-
Indexes -1 through -3 are in range.
-
Index -4 is out of range.
Although the effective index into an array is always an integer, some methods (both within and outside of class Array
) accept one or more non-integer arguments that are integer-convertible objects
.
Creating Arrays
You can create an Array
object explicitly with:
-
An
array literal
:[1, 'one', :one, [2, 'two', :two]]
-
A
%w or %W: string-array Literal
:%w[foo bar baz] # => ["foo", "bar", "baz"] %w[1 % *] # => ["1", "%", "*"]
-
A
%i pr %I: symbol-array Literal
:%i[foo bar baz] # => [:foo, :bar, :baz] %i[1 % *] # => [:"1", :%, :*]
-
Method Kernel.Array:
Array(["a", "b"]) # => ["a", "b"] Array(1..5) # => [1, 2, 3, 4, 5] Array(key: :value) # => [[:key, :value]] Array(nil) # => [] Array(1) # => [1] Array({:a => "a", :b => "b"}) # => [[:a, "a"], [:b, "b"]]
-
Method .new:
Array.new # => [] Array.new(3) # => [nil, nil, nil] Array.new(4) {Hash.new} # => [{}, {}, {}, {}] Array.new(3, true) # => [true, true, true]
Note that the last example above populates the array with references to the same object. This is recommended only in cases where that object is a natively immutable object such as a symbol, a numeric,
nil
,true
, orfalse
.Another way to create an array with various objects, using a block; this usage is safe for mutable objects such as hashes, strings or other arrays:
Array.new(4) {|i| i.to_s } # => ["0", "1", "2", "3"]
Here is a way to create a multi-dimensional array:
Array.new(3) {Array.new(3)} # => [[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]]
A number of Ruby methods, both in the core and in the standard library, provide instance method #to_a, which converts an object to an array.
-
OptionParser#to_a
-
Set#to_a
-
Benchmark::Tms#to_a
-
CSV::Table#to_a
-
Gem::List#to_a
-
Gem::NameTuple#to_a
-
Gem::Platform#to_a
-
Gem::RequestSet::Lockfile::Tokenizer#to_a
-
Gem::SourceList#to_a
-
OpenSSL::X509::Extension#to_a
-
OpenSSL::X509::Name#to_a
-
Racc::ISet#to_a
-
Rinda::RingFinger#to_a
-
Ripper::Lexer::Elem#to_a
-
YAML::DBM#to_a
Example Usage
In addition to the methods it mixes in through the ::Enumerable
module, the Array
class has proprietary methods for accessing, searching and otherwise manipulating arrays.
Some of the more common ones are illustrated below.
Accessing Elements
Elements in an array can be retrieved using the #[] method. It can take a single integer argument (a numeric index), a pair of arguments (start and length) or a range. Negative indices start counting from the end, with -1 being the last element.
arr = [1, 2, 3, 4, 5, 6]
arr[2] #=> 3
arr[100] #=> nil
arr[-3] #=> 4
arr[2, 3] #=> [3, 4, 5]
arr[1..4] #=> [2, 3, 4, 5]
arr[1..-3] #=> [2, 3, 4]
Another way to access a particular array element is by using the #at method
arr.at(0) #=> 1
The #slice method works in an identical manner to #[].
To raise an error for indices outside of the array bounds or else to provide a default value when that happens, you can use #fetch.
arr = ['a', 'b', 'c', 'd', 'e', 'f']
arr.fetch(100) #=> IndexError: index 100 outside of array bounds: -6...6
arr.fetch(100, "oops") #=> "oops"
The special methods #first and #last will return the first and last elements of an array, respectively.
arr.first #=> 1
arr.last #=> 6
To return the first n
elements of an array, use #take
arr.take(3) #=> [1, 2, 3]
#drop does the opposite of #take, by returning the elements after n
elements have been dropped:
arr.drop(3) #=> [4, 5, 6]
Obtaining Information about an Array
Arrays keep track of their own length at all times. To query an array about the number of elements it contains, use #length, #count or #size.
browsers = ['Chrome', 'Firefox', 'Safari', 'Opera', 'IE']
browsers.length #=> 5
browsers.count #=> 5
To check whether an array contains any elements at all
browsers.empty? #=> false
To check whether a particular item is included in the array
browsers.include?('Konqueror') #=> false
Adding Items to Arrays
Items can be added to the end of an array by using either #push or #<<
arr = [1, 2, 3, 4]
arr.push(5) #=> [1, 2, 3, 4, 5]
arr << 6 #=> [1, 2, 3, 4, 5, 6]
#unshift will add a new item to the beginning of an array.
arr.unshift(0) #=> [0, 1, 2, 3, 4, 5, 6]
With #insert you can add a new element to an array at any position.
arr.insert(3, 'apple') #=> [0, 1, 2, 'apple', 3, 4, 5, 6]
Using the #insert method, you can also insert multiple values at once:
arr.insert(3, 'orange', 'pear', 'grapefruit')
#=> [0, 1, 2, "orange", "pear", "grapefruit", "apple", 3, 4, 5, 6]
Removing Items from an Array
The method #pop removes the last element in an array and returns it:
arr = [1, 2, 3, 4, 5, 6]
arr.pop #=> 6
arr #=> [1, 2, 3, 4, 5]
To retrieve and at the same time remove the first item, use #shift:
arr.shift #=> 1
arr #=> [2, 3, 4, 5]
To delete an element at a particular index:
arr.delete_at(2) #=> 4
arr #=> [2, 3, 5]
To delete a particular element anywhere in an array, use #delete:
arr = [1, 2, 2, 3]
arr.delete(2) #=> 2
arr #=> [1,3]
A useful method if you need to remove nil
values from an array is #compact:
arr = ['foo', 0, nil, 'bar', 7, 'baz', nil]
arr.compact #=> ['foo', 0, 'bar', 7, 'baz']
arr #=> ['foo', 0, nil, 'bar', 7, 'baz', nil]
arr.compact! #=> ['foo', 0, 'bar', 7, 'baz']
arr #=> ['foo', 0, 'bar', 7, 'baz']
Another common need is to remove duplicate elements from an array.
It has the non-destructive #uniq, and destructive method #uniq!
arr = [2, 5, 6, 556, 6, 6, 8, 9, 0, 123, 556]
arr.uniq #=> [2, 5, 6, 556, 8, 9, 0, 123]
Iterating over Arrays
Like all classes that include the ::Enumerable
module, Array
has an each method, which defines what elements should be iterated over and how. In case of Array’s #each, all elements in the Array
instance are yielded to the supplied block in sequence.
Note that this operation leaves the array unchanged.
arr = [1, 2, 3, 4, 5]
arr.each {|a| print a -= 10, " "}
# prints: -9 -8 -7 -6 -5
#=> [1, 2, 3, 4, 5]
Another sometimes useful iterator is #reverse_each which will iterate over the elements in the array in reverse order.
words = %w[first second third fourth fifth sixth]
str = ""
words.reverse_each {|word| str += "#{word} "}
p str #=> "sixth fifth fourth third second first "
The #map method can be used to create a new array based on the original array, but with the values modified by the supplied block:
arr.map {|a| 2*a} #=> [2, 4, 6, 8, 10]
arr #=> [1, 2, 3, 4, 5]
arr.map! {|a| a**2} #=> [1, 4, 9, 16, 25]
arr #=> [1, 4, 9, 16, 25]
Selecting Items from an Array
Elements can be selected from an array according to criteria defined in a block. The selection can happen in a destructive or a non-destructive manner. While the destructive operations will modify the array they were called on, the non-destructive methods usually return a new array with the selected elements, but leave the original array unchanged.
Non-destructive Selection
arr = [1, 2, 3, 4, 5, 6]
arr.select {|a| a > 3} #=> [4, 5, 6]
arr.reject {|a| a < 3} #=> [3, 4, 5, 6]
arr.drop_while {|a| a < 4} #=> [4, 5, 6]
arr #=> [1, 2, 3, 4, 5, 6]
Destructive Selection
#select! and #reject! are the corresponding destructive methods to #select and #reject
Similar to #select vs. #reject, #delete_if and #keep_if have the exact opposite result when supplied with the same block:
arr.delete_if {|a| a < 4} #=> [4, 5, 6]
arr #=> [4, 5, 6]
arr = [1, 2, 3, 4, 5, 6]
arr.keep_if {|a| a < 4} #=> [1, 2, 3]
arr #=> [1, 2, 3]
What’s Here
First, what’s elsewhere. Class Array
:
-
Inherits from
class Object
. -
Includes
module Enumerable
, which provides dozens of additional methods.
Here, class Array
provides methods that are useful for:
-
{Array@Methods+for+Creating+an+Array Creating an }
-
Querying
-
Comparing
-
Fetching
-
Assigning
-
Deleting
-
Combining
-
Iterating
-
Converting
-
And more.…
Methods for Creating an Array
-
.[]: Returns a new array populated with given objects.
-
.new: Returns a new array.
-
.try_convert: Returns a new array created from a given object.
See also Creating s
.
Methods for Querying
-
#empty?: Returns whether there are no elements.
-
#all?: Returns whether all elements meet a given criterion.
-
#any?: Returns whether any element meets a given criterion.
-
#one?: Returns whether exactly one element #== a given object.
-
#count: Returns the count of elements that meet a given criterion.
-
#find_index (aliased as #index): Returns the index of the first element that meets a given criterion.
-
#rindex: Returns the index of the last element that meets a given criterion.
-
#hash: Returns the integer hash code.
Methods for Comparing
-
#<=>: Returns -1, 0, or 1, as
self
is less than, equal to, or greater than a given object. -
#==: Returns whether each element in
self
is #== to the corresponding element in a given object. -
#eql?: Returns whether each element in
self
is #eql? to the corresponding element in a given object.
Methods for Fetching
These methods do not modify self
.
-
#[] (aliased as #slice): Returns consecutive elements as determined by a given argument.
-
#fetch: Returns the element at a given offset.
-
#fetch_values: Returns elements at given offsets.
-
#first: Returns one or more leading elements.
-
#last: Returns one or more trailing elements.
-
#max: Returns one or more maximum-valued elements, as determined by #<=> or a given block.
-
#min: Returns one or more minimum-valued elements, as determined by #<=> or a given block.
-
#minmax: Returns the minimum-valued and maximum-valued elements, as determined by #<=> or a given block.
-
#assoc: Returns the first element that is an array whose first element #== a given object.
-
#rassoc: Returns the first element that is an array whose second element #== a given object.
-
#at: Returns the element at a given offset.
-
#values_at: Returns the elements at given offsets.
-
#dig: Returns the object in nested objects that is specified by a given index and additional arguments.
-
#drop: Returns trailing elements as determined by a given index.
-
#take: Returns leading elements as determined by a given index.
-
#drop_while: Returns trailing elements as determined by a given block.
-
#take_while: Returns leading elements as determined by a given block.
-
#sort: Returns all elements in an order determined by #<=> or a given block.
-
#reverse: Returns all elements in reverse order.
-
#compact: Returns an array containing all non-
nil
elements. -
#select (aliased as #filter): Returns an array containing elements selected by a given block.
-
#uniq: Returns an array containing non-duplicate elements.
-
#rotate: Returns all elements with some rotated from one end to the other.
-
#bsearch: Returns an element selected via a binary search as determined by a given block.
-
#bsearch_index: Returns the index of an element selected via a binary search as determined by a given block.
-
#sample: Returns one or more random elements.
-
#shuffle: Returns elements in a random order.
-
#reject: Returns an array containing elements not rejected by a given block.
Methods for Assigning
These methods add, replace, or reorder elements in self
.
-
#[]=: Assigns specified elements with a given object.
-
#<<: Appends an element.
-
#insert: Inserts given objects at a given offset; does not replace elements.
-
#concat: Appends all elements from given arrays.
-
#fill: Replaces specified elements with specified objects.
-
#flatten!: Replaces each nested array in
self
with the elements from that array. -
#initialize_copy (aliased as #replace): Replaces the content of
self
with the content of a given array. -
#reverse!: Replaces
self
with its elements reversed. -
#rotate!: Replaces
self
with its elements rotated. -
#shuffle!: Replaces
self
with its elements in random order. -
#sort!: Replaces
self
with its elements sorted, as determined by #<=> or a given block. -
#sort_by!: Replaces
self
with its elements sorted, as determined by a given block.
Methods for Deleting
Each of these methods removes elements from self
:
-
#pop: Removes and returns the last element.
-
#shift: Removes and returns the first element.
-
#compact!: Removes all
nil
elements. -
#delete: Removes elements equal to a given object.
-
#delete_at: Removes the element at a given offset.
-
#delete_if: Removes elements specified by a given block.
-
#clear: Removes all elements.
-
#keep_if: Removes elements not specified by a given block.
-
#reject!: Removes elements specified by a given block.
-
#select! (aliased as #filter!): Removes elements not specified by a given block.
-
#slice!: Removes and returns a sequence of elements.
-
#uniq!: Removes duplicates.
Methods for Combining
-
#&: Returns an array containing elements found both in
self
and a given array. -
#intersection: Returns an array containing elements found both in
self
and in each given array. -
#+: Returns an array containing all elements of
self
followed by all elements of a given array. -
#-: Returns an array containing all elements of
self
that are not found in a given array. -
#|: Returns an array containing all elements of
self
and all elements of a given array, duplicates removed. -
#union: Returns an array containing all elements of
self
and all elements of given arrays, duplicates removed. -
#difference: Returns an array containing all elements of
self
that are not found in any of the given arrays.. -
#product: Returns or yields all combinations of elements from
self
and given arrays. -
#reverse: Returns an array containing all elements of
self
in reverse order.
Methods for Iterating
-
#each: Passes each element to a given block.
-
#reverse_each: Passes each element, in reverse order, to a given block.
-
#each_index: Passes each element index to a given block.
-
#cycle: Calls a given block with each element, then does so again, for a specified number of times, or forever.
-
#combination: Calls a given block with combinations of elements of
self
; a combination does not use the same element more than once. -
#permutation: Calls a given block with permutations of elements of
self
; a permutation does not use the same element more than once. -
#repeated_combination: Calls a given block with combinations of elements of
self
; a combination may use the same element more than once. -
#repeated_permutation: Calls a given block with permutations of elements of
self
; a permutation may use the same element more than once.
Methods for Converting
-
#collect (aliased as #map): Returns an array containing the block return-value for each element.
-
#collect! (aliased as #map!): Replaces each element with a block return-value.
-
#flatten: Returns an array that is a recursive flattening of
self
. -
#inspect (aliased as #to_s): Returns a new
::String
containing the elements. -
#join: Returns a newsString containing the elements joined by the field separator.
-
#to_a: Returns
self
or a new array containing all elements. -
#to_ary: Returns
self
. -
#to_h: Returns a new hash formed from the elements.
-
#transpose: Transposes
self
, which must be an array of arrays. -
#zip: Returns a new array of arrays containing
self
and given arrays; follow the link for details.
Other Methods
-
#*: Returns one of the following:
-
With integer argument
n
, a new array that is the concatenation ofn
copies ofself
. -
With string argument
field_separator
, a new string that is equivalent tojoin(field_separator)
.
-
-
#pack: Packs the elements into a binary sequence.
-
#sum: Returns a sum of elements according to either
+
or a given block.
Class Method Summary
-
.[](*args)
Returns a new array, populated with the given objects:
-
.try_convert(object) ⇒ Object, ...
Attempts to return an array, based on the given
object
. - .new(*args) constructor Internal use only
Instance Attribute Summary
-
#empty? ⇒ Boolean
readonly
Returns
true
if the count of elements inself
is zero,false
otherwise.
Instance Method Summary
-
#&(other_array) ⇒ Array
Returns a new array containing the intersection of
self
andother_array
; that is, containing those elements found in bothself
andother_array
: -
#*(n) ⇒ Array
When non-negative integer argument
n
is given, returns a new array built by concatenatingn
copies ofself
: -
#+(other_array) ⇒ Array
Returns a new array containing all elements of
self
followed by all elements ofother_array
: -
#-(other_array) ⇒ Array
Returns a new array containing only those elements of
self
that are not found inother_array
; the order fromself
is preserved: -
#<<(object) ⇒ self
Appends
object
as the last element inself
; returnsself
: -
#<=>(other_array) ⇒ 1, 0
Returns -1, 0, or 1 as
self
is determined to be less than, equal to, or greater thanother_array
. -
#==(other_array) ⇒ Boolean
Returns whether both:
-
#[](index) ⇒ Object?
(also: #slice)
Returns elements from
self
; does not modifyself
. -
#[]=(index, object) ⇒ Object
Assigns elements in
self
, based on the givenobject
; returnsobject
. -
#all? ⇒ Boolean
Returns whether for every element of
self
, a given criterion is satisfied. -
#any? ⇒ Boolean
Returns whether for any element of
self
, a given criterion is satisfied. -
#append(*objects) ⇒ self
Alias for #push.
-
#assoc(object) ⇒ Array?
Returns the first element
ele
inself
such thatele
is an array andele[0] == object
: - #at(index) ⇒ Object?
-
#bsearch {|element| ... } ⇒ found_element?
Returns the element from
self
found by a binary search, ornil
if the search found no suitable element. -
#bsearch_index {|element| ... } ⇒ Integer?
Returns the integer index of the element from
self
found by a binary search, ornil
if the search found no suitable element. -
#clear ⇒ self
Removes all elements from
self
; returnsself
: -
#collect {|element| ... } ⇒ Array
Alias for #map.
-
#collect! {|element| ... } ⇒ Array
Alias for #map!.
-
#combination(n) {|element| ... } ⇒ self
When a block and a positive
integer-convertible object
argumentn
(0 < n <= self.size
) are given, calls the block with alln
-tuple combinations ofself
; returnsself
: -
#compact ⇒ Array
Returns a new array containing only the non-
nil
elements fromself
; element order is preserved: -
#compact! ⇒ self?
Removes all
nil
elements fromself
; Returnsself
if any elements are removed,nil
otherwise: -
#concat(*other_arrays) ⇒ self
Adds to
self
all elements from each array inother_arrays
; returnsself
: -
#count ⇒ Integer
Returns a count of specified elements.
- #cycle(count = nil) {|element| ... } ⇒ nil
-
#delete(object) ⇒ last_removed_object
Removes zero or more elements from
self
. -
#delete_at(index) ⇒ removed_object?
Removes the element of
self
at the given #index, which must be aninteger-convertible object
. -
#delete_if {|element| ... } ⇒ self
With a block given, calls the block with each element of
self
; removes the element if the block returns a truthy value; returnsself
: -
#difference(*other_arrays = []) ⇒ Array
Returns a new array containing only those elements from
self
that are not found in any of the givenother_arrays
; items are compared using #eql?; order fromself
is preserved: -
#dig(index, *identifiers) ⇒ Object
Finds and returns the object in nested object specified by #index and
identifiers
; the nested objects may be instances of various classes. -
#drop(n) ⇒ Array
Returns a new array containing all but the first
n
element ofself
, wheren
is a non-negative Integer; does not modifyself
. -
#drop_while {|element| ... } ⇒ Array
With a block given, calls the block with each successive element of
self
; stops if the block returnsfalse
ornil
; returns a new array omitting those elements for which the block returned a truthy value; does not modifyself
: -
#each {|element| ... } ⇒ self
With a block given, iterates over the elements of
self
, passing each element to the block; returnsself
: -
#each_index {|index| ... } ⇒ self
With a block given, iterates over the elements of
self
, passing each array index to the block; returnsself
: -
#eql?(other_array) ⇒ Boolean
Returns
true
ifself
andother_array
are the same size, and if, for each indexi
inself
,self[i].eql?(other_array[i])
: - #fetch(index) ⇒ element
-
#fetch_values(*indexes) ⇒ Array
With no block given, returns a new array containing the elements of
self
at the offsets given byindexes
; each of theindexes
must be aninteger-convertible object
: -
#fill(object, start = nil, count = nil) ⇒ Array
Replaces selected elements in
self
; may add elements toself
; always returnsself
(never a new array). -
#filter {|element| ... } ⇒ Array
(also: #select)
With a block given, calls the block with each element of
self
; returns a new array containing those elements ofself
for which the block returns a truthy value: -
#filter! {|element| ... } ⇒ self?
(also: #select!)
With a block given, calls the block with each element of
self
; removes fromself
those elements for which the block returnsfalse
ornil
. -
#find_index(object) ⇒ Integer?
Alias for #index.
-
#first ⇒ Object?
Returns elements from
self
, ornil
; does not modifyself
. -
#flatten(depth = nil) ⇒ Array
Returns a new array that is a recursive flattening of
self
todepth
levels of recursion;depth
must be aninteger-convertible object
ornil
. -
#flatten!(depth = nil) ⇒ self?
Returns
self
as a recursively flattening ofself
todepth
levels of recursion;depth
must be aninteger-convertible object
, ornil
. -
#freeze ⇒ self
Freezes
self
(if not already frozen); returnsself
: -
#hash ⇒ Integer
Returns the integer hash value for
self
. -
#include?(object) ⇒ Boolean
Returns whether for some element
element
inself
,object == element
: -
#index(object) ⇒ Integer?
(also: #find_index)
Returns the zero-based integer index of a specified element, or
nil
. -
#new ⇒ Array
constructor
Returns a new array.
-
#initialize_copy(other_array) ⇒ self
Alias for #replace.
-
#insert(index, *objects) ⇒ self
Inserts the given
objects
as elements ofself
; returnsself
. -
#inspect ⇒ String
Alias for #to_s.
-
#intersect?(other_array) ⇒ Boolean
Returns whether
other_array
has at least one element that is #eql? to some element ofself
: -
#intersection(*other_arrays) ⇒ Array
Returns a new array containing each element in
self
that is #eql? to at least one element in each of the givenother_arrays
; duplicates are omitted: -
#join(separator = $,) ⇒ String
Returns the new string formed by joining the converted elements of
self
; for each elementelement
: -
#keep_if {|element| ... } ⇒ self
With a block given, calls the block with each element of
self
; removes the element fromself
if the block does not return a truthy value: -
#last ⇒ last_object?
Returns elements from
self
, ornil
;self
is not modified. -
#length ⇒ Integer
(also: #size)
Returns the count of elements in
self
: -
#map {|element| ... } ⇒ Array
(also: #collect)
With a block given, calls the block with each element of
self
; returns a new array whose elements are the return values from the block: -
#map! {|element| ... } ⇒ Array
(also: #collect!)
With a block given, calls the block with each element of
self
and replaces the element with the block’s return value; returnsself
: -
#max ⇒ element
Returns one of the following:
-
#min ⇒ element
Returns one of the following:
-
#minmax ⇒ Array
Returns a 2-element array containing the minimum-valued and maximum-valued elements from
self
; does not modifyself
. -
#none? ⇒ Boolean
Returns
true
if no element ofself
meets a given criterion,false
otherwise. -
#one? ⇒ Boolean
Returns
true
if exactly one element ofself
meets a given criterion. -
#pack(template, buffer: nil) ⇒ String
Formats each element in
self
into a binary string; returns that string. -
#permutation(n = self.size) {|permutation| ... } ⇒ self
Iterates over permutations of the elements of
self
; the order of permutations is indeterminate. -
#pop ⇒ Object?
Removes and returns trailing elements of
self
. -
#prepend(*objects) ⇒ self
(also: #unshift)
Prepends the given
objects
toself
: -
#product(*other_arrays) ⇒ Array
Computes all combinations of elements from all the arrays, including both
self
andother_arrays
: -
#push(*objects) ⇒ self
(also: #append)
Appends each argument in
objects
toself
; returnsself
: -
#rassoc(object) ⇒ Array?
Returns the first element
ele
inself
such thatele
is an array andele[1] == object
: -
#reject {|element| ... } ⇒ Array
With a block given, returns a new array whose elements are all those from
self
for which the block returnsfalse
ornil
: -
#reject! {|element| ... } ⇒ self?
With a block given, calls the block with each element of
self
; removes each element for which the block returns a truthy value. -
#repeated_combination(size) {|combination| ... } ⇒ self
With a block given, calls the block with each repeated combination of length #size of the elements of
self
; each combination is an array; returnsself
. -
#repeated_permutation(size) {|permutation| ... } ⇒ self
With a block given, calls the block with each repeated permutation of length #size of the elements of
self
; each permutation is an array; returnsself
. -
#replace(other_array) ⇒ self
(also: #initialize_copy)
Replaces the elements of
self
with the elements ofother_array
, which must be anarray-convertible object
; returnsself
: -
#reverse ⇒ Array
Returns a new array containing the elements of
self
in reverse order: -
#reverse! ⇒ self
Reverses the order of the elements of
self
; returnsself
: -
#reverse_each {|element| ... } ⇒ self
When a block given, iterates backwards over the elements of
self
, passing, in reverse order, each element to the block; returnsself
: -
#rindex(object) ⇒ Integer?
Returns the index of the last element for which
object == element
. -
#rotate(count = 1) ⇒ Array
Returns a new array formed from
self
with elements rotated from one end to the other. -
#rotate!(count = 1) ⇒ self
Rotates
self
in place by moving elements from one end to the other; returnsself
. -
#sample(random: Random) ⇒ Object
Returns random elements from
self
, as selected by the object given by keyword argumentrandom
. -
#select {|element| ... } ⇒ Array
Alias for #filter.
-
#select! {|element| ... } ⇒ self?
Alias for #filter!.
-
#shift ⇒ Object?
Removes and returns leading elements from
self
. -
#shuffle(random: Random) ⇒ Array
Returns a new array containing all elements from
self
in a random order, as selected by the object given by keyword argumentrandom
: -
#shuffle!(random: Random) ⇒ self
Shuffles all elements in
self
into a random order, as selected by the object given by keyword argumentrandom
; returnsself
: -
#size ⇒ Integer
Alias for #length.
-
#slice(index) ⇒ Object?
Alias for #[].
-
#slice!(index) ⇒ Object?
Removes and returns elements from
self
. -
#sort ⇒ Array
Returns a new array containing the elements of
self
, sorted. -
#sort! ⇒ self
Like #sort, but returns
self
with its elements sorted in place. -
#sort_by! {|element| ... } ⇒ self
With a block given, sorts the elements of
self
in place; returns self. -
#sum(init = 0) ⇒ Object
With no block given, returns the sum of
init
and all elements ofself
; for arrayarray
and valueinit
, equivalent to: - #take(count) ⇒ Array
-
#take_while {|element| ... } ⇒ Array
With a block given, calls the block with each successive element of
self
; stops iterating if the block returnsfalse
ornil
; returns a new array containing those elements for which the block returned a truthy value: -
#to_a ⇒ self, Array
When
self
is an instance ofArray
, returnsself
. -
#to_ary ⇒ self
Returns
self
. -
#to_h ⇒ Hash
Returns a new hash formed from
self
. -
#to_s ⇒ String
(also: #inspect)
Returns the new string formed by calling method #inspect on each array element:
-
#transpose ⇒ Array
Returns a new array that is
self
as a transposed matrix: -
#union(*other_arrays) ⇒ Array
Returns a new array that is the union of the elements of
self
and all given arraysother_arrays
; items are compared using #eql?: -
#uniq ⇒ Array
Returns a new array containing those elements from
self
that are not duplicates, the first occurrence always being retained. -
#uniq! ⇒ self?
Removes duplicate elements from
self
, the first occurrence always being retained; returnsself
if any elements removed,nil
otherwise. -
#unshift(*objects) ⇒ self
Alias for #prepend.
- #values_at(*indexes) ⇒ Array
-
#zip(*other_arrays) ⇒ Array
When no block given, returns a new
Array
new_array
of sizeself.size
whose elements are Arrays. -
#|(other_array) ⇒ Array
Returns the union of
array
andArray
other_array
; duplicates are removed; order is preserved; items are compared using #eql?: - #deconstruct Internal use only
::Enumerable
- Included
#all? | Returns whether every element meets a given criterion. |
#any? | Returns whether any element meets a given criterion. |
#chain | Returns an enumerator object generated from this enumerator and given enumerables. |
#chunk | Each element in the returned enumerator is a 2-element array consisting of: |
#chunk_while | Creates an enumerator for each chunked elements. |
#collect | Alias for Enumerable#map. |
#collect_concat | Alias for Enumerable#flat_map. |
#compact | Returns an array of all non- |
#count | Returns the count of elements, based on an argument or block criterion, if given. |
#cycle | When called with positive integer argument |
#detect | Alias for Enumerable#find. |
#drop | For positive integer |
#drop_while | Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements after that point: |
#each_cons | Calls the block with each successive overlapped |
#each_entry | Calls the given block with each element, converting multiple values from yield to an array; returns |
#each_slice | Calls the block with each successive disjoint |
#each_with_index | Invoke |
#each_with_object | Calls the block once for each element, passing both the element and the given object: |
#entries | Alias for Enumerable#to_a. |
#filter | Returns an array containing elements selected by the block. |
#filter_map | Returns an array containing truthy elements returned by the block. |
#find | Returns the first element for which the block returns a truthy value. |
#find_all | Alias for Enumerable#filter. |
#find_index | Returns the index of the first element that meets a specified criterion, or |
#first | Returns the first element or elements. |
#flat_map | Returns an array of flattened objects returned by the block. |
#grep | Returns an array of objects based elements of |
#grep_v | Returns an array of objects based on elements of |
#group_by | With a block given returns a hash: |
#include? | Alias for Enumerable#member?. |
#inject | Returns the result of applying a reducer to an initial value and the first element of the |
#lazy | Returns an |
#map | Returns an array of objects returned by the block. |
#max | Returns the element with the maximum element according to a given criterion. |
#max_by | Returns the elements for which the block returns the maximum values. |
#member? | Returns whether for any element |
#min | Returns the element with the minimum element according to a given criterion. |
#min_by | Returns the elements for which the block returns the minimum values. |
#minmax | Returns a 2-element array containing the minimum and maximum elements according to a given criterion. |
#minmax_by | Returns a 2-element array containing the elements for which the block returns minimum and maximum values: |
#none? | Returns whether no element meets a given criterion. |
#one? | Returns whether exactly one element meets a given criterion. |
#partition | With a block given, returns an array of two arrays: |
#reduce | Alias for Enumerable#inject. |
#reject | Returns an array of objects rejected by the block. |
#reverse_each | With a block given, calls the block with each element, but in reverse order; returns |
#select | Alias for Enumerable#filter. |
#slice_after | Creates an enumerator for each chunked elements. |
#slice_before | With argument |
#slice_when | Creates an enumerator for each chunked elements. |
#sort | Returns an array containing the sorted elements of |
#sort_by | With a block given, returns an array of elements of |
#sum | With no block given, returns the sum of |
#take | For non-negative integer |
#take_while | Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements up to that point: |
#tally | When argument #hash is not given, returns a new hash whose keys are the distinct elements in |
#to_a | Returns an array containing the items in |
#to_h | When |
#to_set | Makes a set from the enumerable object with given arguments. |
#uniq | With no block, returns a new array containing only unique elements; the array has no two elements |
#zip | With no block given, returns a new array |
Constructor Details
.new(*args)
# File 'array.c', line 1056
static VALUE rb_ary_s_new(int argc, VALUE *argv, VALUE klass) { VALUE ary; if (klass == rb_cArray) { long size = 0; if (argc > 0 && FIXNUM_P(argv[0])) { size = FIX2LONG(argv[0]); if (size < 0) size = 0; } ary = ary_new(klass, size); rb_obj_call_init_kw(ary, argc, argv, RB_PASS_CALLED_KEYWORDS); } else { ary = rb_class_new_instance_pass_kw(argc, argv, klass); } return ary; }
#new ⇒ Array
#new(array) ⇒ Array
#new(size, default_value = nil) ⇒ Array
#new(size = 0) {|index| ... } ⇒ Array
Array
#new(array) ⇒ Array
#new(size, default_value = nil) ⇒ Array
#new(size = 0) {|index| ... } ⇒ Array
Returns a new array.
With no block and no argument given, returns a new empty array:
Array.new # => []
With no block and array argument given, returns a new array with the same elements:
Array.new([:foo, 'bar', 2]) # => [:foo, "bar", 2]
With no block and integer argument given, returns a new array containing that many instances of the given default_value
:
Array.new(0) # => []
Array.new(3) # => [nil, nil, nil]
Array.new(2, 3) # => [3, 3]
With a block given, returns an array of the given #size; calls the block with each #index in the range (0...size)
; the element at that #index in the returned array is the blocks return value:
Array.new(3) {|index| "Element #{index}" } # => ["Element 0", "Element 1", "Element 2"]
A common pitfall for new Rubyists is providing an expression as default_value
:
array = Array.new(2, {})
array # => [{}, {}]
array[0][:a] = 1
array # => [{a: 1}, {a: 1}], as array[0] and array[1] are same object
If you want the elements of the array to be distinct, you should pass a block:
array = Array.new(2) { {} }
array # => [{}, {}]
array[0][:a] = 1
array # => [{a: 1}, {}], as array[0] and array[1] are different objects
Raises TypeError if the first argument is not either an array or an integer-convertible object
). Raises ArgumentError if the first argument is a negative integer.
Related: see Methods for Creating an Array
.
# File 'array.c', line 1130
static VALUE rb_ary_initialize(int argc, VALUE *argv, VALUE ary) { long len; VALUE size, val; rb_ary_modify(ary); if (argc == 0) { rb_ary_reset(ary); RUBY_ASSERT(ARY_EMBED_P(ary)); RUBY_ASSERT(ARY_EMBED_LEN(ary) == 0); if (rb_block_given_p()) { rb_warning("given block not used"); } return ary; } rb_scan_args(argc, argv, "02", &size, &val); if (argc == 1 && !FIXNUM_P(size)) { val = rb_check_array_type(size); if (!NIL_P(val)) { rb_ary_replace(ary, val); return ary; } } len = NUM2LONG(size); /* NUM2LONG() may call size.to_int, ary can be frozen, modified, etc */ if (len < 0) { rb_raise(rb_eArgError, "negative array size"); } if (len > ARY_MAX_SIZE) { rb_raise(rb_eArgError, "array size too big"); } /* recheck after argument conversion */ rb_ary_modify(ary); ary_resize_capa(ary, len); if (rb_block_given_p()) { long i; if (argc == 2) { rb_warn("block supersedes default value argument"); } for (i=0; i<len; i++) { rb_ary_store(ary, i, rb_yield(LONG2NUM(i))); ARY_SET_LEN(ary, i + 1); } } else { ary_memfill(ary, 0, len, val); ARY_SET_LEN(ary, len); } return ary; }
Class Method Details
.[](*args)
Returns a new array, populated with the given objects:
Array[1, 'a', /^A/] # => [1, "a", /^A/]
Array[] # => []
Array.[](1, 'a', /^A/) # => [1, "a", /^A/]
Related: see Methods for Creating an Array
.
# File 'array.c', line 1194
static VALUE rb_ary_s_create(int argc, VALUE *argv, VALUE klass) { VALUE ary = ary_new(klass, argc); if (argc > 0 && argv) { ary_memcpy(ary, 0, argc, argv); ARY_SET_LEN(ary, argc); } return ary; }
.try_convert(object) ⇒ Object, ...
Attempts to return an array, based on the given object
.
If object
is an array, returns object
.
Otherwise if object
responds to :to_ary
. calls object.to_ary
: if the return value is an array or nil
, returns that value; if not, raises ::TypeError
.
Otherwise returns nil
.
Related: see Methods for Creating an Array
.
# File 'array.c', line 1049
static VALUE rb_ary_s_try_convert(VALUE dummy, VALUE ary) { return rb_check_array_type(ary); }
Instance Attribute Details
#empty? ⇒ Boolean
(readonly)
Returns true
if the count of elements in self
is zero, false
otherwise.
Related: see Methods for Querying
.
# File 'array.c', line 2770
static VALUE rb_ary_empty_p(VALUE ary) { return RBOOL(RARRAY_LEN(ary) == 0); }
Instance Method Details
#&(other_array) ⇒ Array
Returns a new array containing the intersection of self
and other_array
; that is, containing those elements found in both self
and other_array
:
[0, 1, 2, 3] & [1, 2] # => [1, 2]
Omits duplicates:
[0, 1, 1, 0] & [0, 1] # => [0, 1]
Preserves order from self
:
[0, 1, 2] & [3, 2, 1, 0] # => [0, 1, 2]
Identifies common elements using method #eql? (as defined in each element of self
).
Related: see Methods for Combining
.
# File 'array.c', line 5559
static VALUE rb_ary_and(VALUE ary1, VALUE ary2) { VALUE hash, ary3, v; st_data_t vv; long i; ary2 = to_ary(ary2); ary3 = rb_ary_new(); if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return ary3; if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) { for (i=0; i<RARRAY_LEN(ary1); i++) { v = RARRAY_AREF(ary1, i); if (!rb_ary_includes_by_eql(ary2, v)) continue; if (rb_ary_includes_by_eql(ary3, v)) continue; rb_ary_push(ary3, v); } return ary3; } hash = ary_make_hash(ary2); for (i=0; i<RARRAY_LEN(ary1); i++) { v = RARRAY_AREF(ary1, i); vv = (st_data_t)v; if (rb_hash_stlike_delete(hash, &vv, 0)) { rb_ary_push(ary3, v); } } return ary3; }
#*(n) ⇒ Array
#*(string_separator) ⇒ String
Array
#*(string_separator) ⇒ String
When non-negative integer argument n
is given, returns a new array built by concatenating n
copies of self
:
a = ['x', 'y']
a * 3 # => ["x", "y", "x", "y", "x", "y"]
When string argument string_separator
is given, equivalent to self.join(string_separator)
:
[0, [0, 1], {foo: 0}] * ', ' # => "0, 0, 1, {:foo=>0}"
# File 'array.c', line 5004
static VALUE rb_ary_times(VALUE ary, VALUE times) { VALUE ary2, tmp; const VALUE *ptr; long t, len; tmp = rb_check_string_type(times); if (!NIL_P(tmp)) { return rb_ary_join(ary, tmp); } len = NUM2LONG(times); if (len == 0) { ary2 = ary_new(rb_cArray, 0); goto out; } if (len < 0) { rb_raise(rb_eArgError, "negative argument"); } if (ARY_MAX_SIZE/len < RARRAY_LEN(ary)) { rb_raise(rb_eArgError, "argument too big"); } len *= RARRAY_LEN(ary); ary2 = ary_new(rb_cArray, len); ARY_SET_LEN(ary2, len); ptr = RARRAY_CONST_PTR(ary); t = RARRAY_LEN(ary); if (0 < t) { ary_memcpy(ary2, 0, t, ptr); while (t <= len/2) { ary_memcpy(ary2, t, t, RARRAY_CONST_PTR(ary2)); t *= 2; } if (t < len) { ary_memcpy(ary2, t, len-t, RARRAY_CONST_PTR(ary2)); } } out: return ary2; }
#+(other_array) ⇒ Array
Returns a new array containing all elements of self
followed by all elements of other_array
:
a = [0, 1] + [2, 3]
a # => [0, 1, 2, 3]
Related: see Methods for Combining
.
# File 'array.c', line 4917
VALUE rb_ary_plus(VALUE x, VALUE y) { VALUE z; long len, xlen, ylen; y = to_ary(y); xlen = RARRAY_LEN(x); ylen = RARRAY_LEN(y); len = xlen + ylen; z = rb_ary_new2(len); ary_memcpy(z, 0, xlen, RARRAY_CONST_PTR(x)); ary_memcpy(z, xlen, ylen, RARRAY_CONST_PTR(y)); ARY_SET_LEN(z, len); return z; }
#-(other_array) ⇒ Array
Returns a new array containing only those elements of self
that are not found in other_array
; the order from self
is preserved:
[0, 1, 1, 2, 1, 1, 3, 1, 1] - [1] # => [0, 2, 3]
[0, 1, 1, 2, 1, 1, 3, 1, 1] - [3, 2, 0, :foo] # => [1, 1, 1, 1, 1, 1]
[0, 1, 2] - [:foo] # => [0, 1, 2]
Element are compared using method #eql? (as defined in each element of self
).
Related: see Methods for Combining
.
# File 'array.c', line 5450
VALUE rb_ary_diff(VALUE ary1, VALUE ary2) { VALUE ary3; VALUE hash; long i; ary2 = to_ary(ary2); if (RARRAY_LEN(ary2) == 0) { return ary_make_shared_copy(ary1); } ary3 = rb_ary_new(); if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN || RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) { for (i=0; i<RARRAY_LEN(ary1); i++) { VALUE elt = rb_ary_elt(ary1, i); if (rb_ary_includes_by_eql(ary2, elt)) continue; rb_ary_push(ary3, elt); } return ary3; } hash = ary_make_hash(ary2); for (i=0; i<RARRAY_LEN(ary1); i++) { if (rb_hash_stlike_lookup(hash, RARRAY_AREF(ary1, i), NULL)) continue; rb_ary_push(ary3, rb_ary_elt(ary1, i)); } return ary3; }
#<<(object) ⇒ self
Appends object
as the last element in self
; returns self
:
[:foo, 'bar', 2] << :baz # => [:foo, "bar", 2, :baz]
Appends object
as a single element, even if it is another array:
[:foo, 'bar', 2] << [3, 4] # => [:foo, "bar", 2, [3, 4]]
Related: see Methods for Assigning
.
# File 'array.c', line 1383
VALUE rb_ary_push(VALUE ary, VALUE item) { long idx = RARRAY_LEN((ary_verify(ary), ary)); VALUE target_ary = ary_ensure_room_for_push(ary, 1); RARRAY_PTR_USE(ary, ptr, { RB_OBJ_WRITE(target_ary, &ptr[idx], item); }); ARY_SET_LEN(ary, idx + 1); ary_verify(ary); return ary; }
#<=>(other_array) ⇒ 1
, 0
Returns -1, 0, or 1 as self
is determined to be less than, equal to, or greater than other_array
.
Iterates over each index i
in (0...self.size)
:
-
Computes
result[i]
asself[i] <=> other_array[i]
. -
Immediately returns 1 if
result[i]
is 1:[0, 1, 2] <=> [0, 0, 2] # => 1
-
Immediately returns -1 if
result[i]
is -1:[0, 1, 2] <=> [0, 2, 2] # => -1
-
Continues if
result[i]
is 0.
When every result
is 0, returns self.size <=> other_array.size
(see Integer#<=>):
[0, 1, 2] <=> [0, 1] # => 1
[0, 1, 2] <=> [0, 1, 2] # => 0
[0, 1, 2] <=> [0, 1, 2, 3] # => -1
Note that when other_array
is larger than self
, its trailing elements do not affect the result:
[0, 1, 2] <=> [0, 1, 2, -3] # => -1
[0, 1, 2] <=> [0, 1, 2, 0] # => -1
[0, 1, 2] <=> [0, 1, 2, 3] # => -1
Related: see Methods for Comparing
.
# File 'array.c', line 5367
VALUE rb_ary_cmp(VALUE ary1, VALUE ary2) { long len; VALUE v; ary2 = rb_check_array_type(ary2); if (NIL_P(ary2)) return Qnil; if (ary1 == ary2) return INT2FIX(0); v = rb_exec_recursive_paired(recursive_cmp, ary1, ary2, ary2); if (!UNDEF_P(v)) return v; len = RARRAY_LEN(ary1) - RARRAY_LEN(ary2); if (len == 0) return INT2FIX(0); if (len > 0) return INT2FIX(1); return INT2FIX(-1); }
#==(other_array) ⇒ Boolean
Returns whether both:
-
self
andother_array
are the same size. -
Their corresponding elements are the same; that is, for each index
i
in(0...self.size)
,self[i] == other_array[i]
.
Examples:
[:foo, 'bar', 2] == [:foo, 'bar', 2] # => true
[:foo, 'bar', 2] == [:foo, 'bar', 2.0] # => true
[:foo, 'bar', 2] == [:foo, 'bar'] # => false # Different sizes.
[:foo, 'bar', 2] == [:foo, 'bar', 3] # => false # Different elements.
This method is different from method #eql?, which compares elements using Object#eql?.
Related: see Methods for Comparing
.
# File 'array.c', line 5170
static VALUE rb_ary_equal(VALUE ary1, VALUE ary2) { if (ary1 == ary2) return Qtrue; if (!RB_TYPE_P(ary2, T_ARRAY)) { if (!rb_respond_to(ary2, idTo_ary)) { return Qfalse; } return rb_equal(ary2, ary1); } if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse; if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue; return rb_exec_recursive_paired(recursive_equal, ary1, ary2, ary2); }
#[](index) ⇒ Object?
#[](start, length) ⇒ Object?
#[](range) ⇒ Object?
#[](aseq) ⇒ Object?
#slice(index) ⇒ Object?
#slice(start, length) ⇒ Object?
#slice(range) ⇒ Object?
#slice(aseq) ⇒ Object?
Also known as: #slice
Returns elements from self
; does not modify self
.
In brief:
a = [:foo, 'bar', 2]
# Single argument index: returns one element.
a[0] # => :foo # Zero-based index.
a[-1] # => 2 # Negative index counts backwards from end.
# Arguments start and length: returns an array.
a[1, 2] # => ["bar", 2]
a[-2, 2] # => ["bar", 2] # Negative start counts backwards from end.
# Single argument range: returns an array.
a[0..1] # => [:foo, "bar"]
a[0..-2] # => [:foo, "bar"] # Negative range-begin counts backwards from end.
a[-2..2] # => ["bar", 2] # Negative range-end counts backwards from end.
When a single integer argument #index is given, returns the element at offset #index:
a = [:foo, 'bar', 2]
a[0] # => :foo
a[2] # => 2
a # => [:foo, "bar", 2]
If #index is negative, counts backwards from the end of self
:
a = [:foo, 'bar', 2]
a[-1] # => 2
a[-2] # => "bar"
If #index is out of range, returns nil
.
When two ::Integer
arguments start
and #length are given, returns a new Array
of size #length containing successive elements beginning at offset start
:
a = [:foo, 'bar', 2]
a[0, 2] # => [:foo, "bar"]
a[1, 2] # => ["bar", 2]
If start + length
is greater than self.length
, returns all elements from offset start
to the end:
a = [:foo, 'bar', 2]
a[0, 4] # => [:foo, "bar", 2]
a[1, 3] # => ["bar", 2]
a[2, 2] # => [2]
If start == self.size
and length >= 0
, returns a new empty Array
.
If #length is negative, returns nil
.
When a single ::Range
argument range
is given, treats range.min
as start
above and range.size
as #length above:
a = [:foo, 'bar', 2]
a[0..1] # => [:foo, "bar"]
a[1..2] # => ["bar", 2]
Special case: If range.start == a.size
, returns a new empty Array
.
If range.end
is negative, calculates the end index from the end:
a = [:foo, 'bar', 2]
a[0..-1] # => [:foo, "bar", 2]
a[0..-2] # => [:foo, "bar"]
a[0..-3] # => [:foo]
If range.start
is negative, calculates the start index from the end:
a = [:foo, 'bar', 2]
a[-1..2] # => [2]
a[-2..2] # => ["bar", 2]
a[-3..2] # => [:foo, "bar", 2]
If range.start
is larger than the array size, returns nil
.
a = [:foo, 'bar', 2]
a[4..1] # => nil
a[4..0] # => nil
a[4..-1] # => nil
When a single ::Enumerator::ArithmeticSequence
argument aseq
is given, returns an Array
of elements corresponding to the indexes produced by the sequence.
a = ['--', 'data1', '--', 'data2', '--', 'data3']
a[(1..).step(2)] # => ["data1", "data2", "data3"]
Unlike slicing with range, if the start or the end of the arithmetic sequence is larger than array size, throws ::RangeError
.
a = ['--', 'data1', '--', 'data2', '--', 'data3']
a[(1..11).step(2)]
# RangeError (((1..11).step(2)) out of range)
a[(7..).step(2)]
# RangeError (((7..).step(2)) out of range)
If given a single argument, and its type is not one of the listed, tries to convert it to ::Integer
, and raises if it is impossible:
a = [:foo, 'bar', 2]
# Raises TypeError (no implicit conversion of Symbol into Integer):
a[:foo]
Related: see Methods for Fetching
.
# File 'array.c', line 1894
VALUE rb_ary_aref(int argc, const VALUE *argv, VALUE ary) { rb_check_arity(argc, 1, 2); if (argc == 2) { return rb_ary_aref2(ary, argv[0], argv[1]); } return rb_ary_aref1(ary, argv[0]); }
Assigns elements in self
, based on the given object
; returns object
.
In brief:
a_orig = [:foo, 'bar', 2]
# With argument index.
a = a_orig.dup
a[0] = 'foo' # => "foo"
a # => ["foo", "bar", 2]
a = a_orig.dup
a[7] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, nil, "foo"]
# With arguments start and length.
a = a_orig.dup
a[0, 2] = 'foo' # => "foo"
a # => ["foo", 2]
a = a_orig.dup
a[6, 50] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
# With argument range.
a = a_orig.dup
a[0..1] = 'foo' # => "foo"
a # => ["foo", 2]
a = a_orig.dup
a[6..50] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
When Integer argument #index is given, assigns object
to an element in self
.
If #index is non-negative, assigns object
the element at offset #index:
a = [:foo, 'bar', 2]
a[0] = 'foo' # => "foo"
a # => ["foo", "bar", 2]
If #index is greater than self.length
, extends the array:
a = [:foo, 'bar', 2]
a[7] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, nil, "foo"]
If #index is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2]
a[-1] = 'two' # => "two"
a # => [:foo, "bar", "two"]
When Integer arguments start
and #length are given and object
is not an Array
, removes length - 1
elements beginning at offset start
, and assigns object
at offset start
:
a = [:foo, 'bar', 2]
a[0, 2] = 'foo' # => "foo"
a # => ["foo", 2]
If start
is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2]
a[-2, 2] = 'foo' # => "foo"
a # => [:foo, "foo"]
If start
is non-negative and outside the array ( >= self.size
), extends the array with nil
, assigns object
at offset start
, and ignores #length:
a = [:foo, 'bar', 2]
a[6, 50] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
If #length is zero, shifts elements at and following offset start
and assigns object
at offset start
:
a = [:foo, 'bar', 2]
a[1, 0] = 'foo' # => "foo"
a # => [:foo, "foo", "bar", 2]
If #length is too large for the existing array, does not extend the array:
a = [:foo, 'bar', 2]
a[1, 5] = 'foo' # => "foo"
a # => [:foo, "foo"]
When Range argument range
is given and object
is not an Array
, removes length - 1
elements beginning at offset start
, and assigns object
at offset start
:
a = [:foo, 'bar', 2]
a[0..1] = 'foo' # => "foo"
a # => ["foo", 2]
if range.begin
is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2]
a[-2..2] = 'foo' # => "foo"
a # => [:foo, "foo"]
If the array length is less than range.begin
, extends the array with nil
, assigns object
at offset range.begin
, and ignores #length:
a = [:foo, 'bar', 2]
a[6..50] = 'foo' # => "foo"
a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
If range.end
is zero, shifts elements at and following offset start
and assigns object
at offset start
:
a = [:foo, 'bar', 2]
a[1..0] = 'foo' # => "foo"
a # => [:foo, "foo", "bar", 2]
If range.end
is negative, assigns object
at offset start
, retains range.end.abs -1
elements past that, and removes those beyond:
a = [:foo, 'bar', 2]
a[1..-1] = 'foo' # => "foo"
a # => [:foo, "foo"]
a = [:foo, 'bar', 2]
a[1..-2] = 'foo' # => "foo"
a # => [:foo, "foo", 2]
a = [:foo, 'bar', 2]
a[1..-3] = 'foo' # => "foo"
a # => [:foo, "foo", "bar", 2]
a = [:foo, 'bar', 2]
If range.end
is too large for the existing array, replaces array elements, but does not extend the array with nil
values:
a = [:foo, 'bar', 2]
a[1..5] = 'foo' # => "foo"
a # => [:foo, "foo"]
Related: see Methods for Assigning
.
# File 'array.c', line 2499
static VALUE rb_ary_aset(int argc, VALUE *argv, VALUE ary) { long offset, beg, len; rb_check_arity(argc, 2, 3); rb_ary_modify_check(ary); if (argc == 3) { beg = NUM2LONG(argv[0]); len = NUM2LONG(argv[1]); return ary_aset_by_rb_ary_splice(ary, beg, len, argv[2]); } if (FIXNUM_P(argv[0])) { offset = FIX2LONG(argv[0]); return ary_aset_by_rb_ary_store(ary, offset, argv[1]); } if (rb_range_beg_len(argv[0], &beg, &len, RARRAY_LEN(ary), 1)) { /* check if idx is Range */ return ary_aset_by_rb_ary_splice(ary, beg, len, argv[1]); } offset = NUM2LONG(argv[0]); return ary_aset_by_rb_ary_store(ary, offset, argv[1]); }
#all? ⇒ Boolean
#all?(object) ⇒ Boolean
#all? {|element| ... } ⇒ Boolean
Boolean
#all?(object) ⇒ Boolean
#all? {|element| ... } ⇒ Boolean
Returns whether for every element of self
, a given criterion is satisfied.
With no block and no argument, returns whether every element of self
is truthy:
[[], {}, '', 0, 0.0, Object.new].all? # => true # All truthy objects.
[[], {}, '', 0, 0.0, nil].all? # => false # nil is not truthy.
[[], {}, '', 0, 0.0, false].all? # => false # false is not truthy.
With argument object
given, returns whether object === ele
for every element ele
in self
:
[0, 0, 0].all?(0) # => true
[0, 1, 2].all?(1) # => false
['food', 'fool', 'foot'].all?(/foo/) # => true
['food', 'drink'].all?(/foo/) # => false
With a block given, calls the block with each element in self
; returns whether the block returns only truthy values:
[0, 1, 2].all? { |ele| ele < 3 } # => true
[0, 1, 2].all? { |ele| ele < 2 } # => false
With both a block and argument object
given, ignores the block and uses object
as above.
Special case: returns true
if self
is empty (regardless of any given argument or block).
Related: see Methods for Querying
.
# File 'array.c', line 7757
static VALUE rb_ary_all_p(int argc, VALUE *argv, VALUE ary) { long i, len = RARRAY_LEN(ary); rb_check_arity(argc, 0, 1); if (!len) return Qtrue; if (argc) { if (rb_block_given_p()) { rb_warn("given block not used"); } for (i = 0; i < RARRAY_LEN(ary); ++i) { if (!RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) return Qfalse; } } else if (!rb_block_given_p()) { for (i = 0; i < len; ++i) { if (!RTEST(RARRAY_AREF(ary, i))) return Qfalse; } } else { for (i = 0; i < RARRAY_LEN(ary); ++i) { if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qfalse; } } return Qtrue; }
#any? ⇒ Boolean
#any?(object) ⇒ Boolean
#any? {|element| ... } ⇒ Boolean
Boolean
#any?(object) ⇒ Boolean
#any? {|element| ... } ⇒ Boolean
Returns whether for any element of self
, a given criterion is satisfied.
With no block and no argument, returns whether any element of self
is truthy:
[nil, false, []].any? # => true # Array object is truthy.
[nil, false, {}].any? # => true # Hash object is truthy.
[nil, false, ''].any? # => true # String object is truthy.
[nil, false].any? # => false # Nil and false are not truthy.
With argument object
given, returns whether object === ele
for any element ele
in self
:
[nil, false, 0].any?(0) # => true
[nil, false, 1].any?(0) # => false
[nil, false, 'food'].any?(/foo/) # => true
[nil, false, 'food'].any?(/bar/) # => false
With a block given, calls the block with each element in self
; returns whether the block returns any truthy value:
[0, 1, 2].any? {|ele| ele < 1 } # => true
[0, 1, 2].any? {|ele| ele < 0 } # => false
With both a block and argument object
given, ignores the block and uses object
as above.
Special case: returns false
if self
is empty (regardless of any given argument or block).
Related: see Methods for Querying
.
# File 'array.c', line 7690
static VALUE rb_ary_any_p(int argc, VALUE *argv, VALUE ary) { long i, len = RARRAY_LEN(ary); rb_check_arity(argc, 0, 1); if (!len) return Qfalse; if (argc) { if (rb_block_given_p()) { rb_warn("given block not used"); } for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) return Qtrue; } } else if (!rb_block_given_p()) { for (i = 0; i < len; ++i) { if (RTEST(RARRAY_AREF(ary, i))) return Qtrue; } } else { for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qtrue; } } return Qfalse; }
#push(*objects) ⇒ self
#append(*objects) ⇒ self
self
#append(*objects) ⇒ self
Alias for #push.
#assoc(object) ⇒ Array
?
Returns the first element ele
in self
such that ele
is an array and ele[0] == object
:
a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
a.assoc(4) # => [4, 5, 6]
Returns nil
if no such element is found.
Related: Array#rassoc;
see also Methods for Fetching
.
# File 'array.c', line 5064
VALUE rb_ary_assoc(VALUE ary, VALUE key) { long i; VALUE v; for (i = 0; i < RARRAY_LEN(ary); ++i) { v = rb_check_array_type(RARRAY_AREF(ary, i)); if (!NIL_P(v) && RARRAY_LEN(v) > 0 && rb_equal(RARRAY_AREF(v, 0), key)) return v; } return Qnil; }
#at(index) ⇒ Object?
Returns the element of self
specified by the given #index or nil
if there is no such element; #index must be an integer-convertible object
.
For non-negative #index, returns the element of self
at offset #index:
a = [:foo, 'bar', 2]
a.at(0) # => :foo
a.at(2) # => 2
a.at(2.0) # => 2
For negative #index, counts backwards from the end of self
:
a.at(-2) # => "bar"
Related: Array#[]; see also Methods for Fetching
.
# File 'array.c', line 1961
VALUE rb_ary_at(VALUE ary, VALUE pos) { return rb_ary_entry(ary, NUM2LONG(pos)); }
#bsearch {|element| ... } ⇒ found_element
?
#bsearch ⇒ Enumerator
found_element
?
#bsearch ⇒ Enumerator
Returns the element from self
found by a binary search, or nil
if the search found no suitable element.
See Binary Searching
.
Related: see Methods for Fetching
.
# File 'array.c', line 3509
static VALUE rb_ary_bsearch(VALUE ary) { VALUE index_result = rb_ary_bsearch_index(ary); if (FIXNUM_P(index_result)) { return rb_ary_entry(ary, FIX2LONG(index_result)); } return index_result; }
#bsearch_index {|element| ... } ⇒ Integer?
#bsearch_index ⇒ Enumerator
Returns the integer index of the element from self
found by a binary search, or nil
if the search found no suitable element.
See Binary Searching
.
Related: see Methods for Fetching
.
# File 'array.c', line 3533
static VALUE rb_ary_bsearch_index(VALUE ary) { long low = 0, high = RARRAY_LEN(ary), mid; int smaller = 0, satisfied = 0; VALUE v, val; RETURN_ENUMERATOR(ary, 0, 0); while (low < high) { mid = low + ((high - low) / 2); val = rb_ary_entry(ary, mid); v = rb_yield(val); if (FIXNUM_P(v)) { if (v == INT2FIX(0)) return INT2FIX(mid); smaller = (SIGNED_VALUE)v < 0; /* Fixnum preserves its sign-bit */ } else if (v == Qtrue) { satisfied = 1; smaller = 1; } else if (!RTEST(v)) { smaller = 0; } else if (rb_obj_is_kind_of(v, rb_cNumeric)) { const VALUE zero = INT2FIX(0); switch (rb_cmpint(rb_funcallv(v, id_cmp, 1, &zero), v, zero)) { case 0: return INT2FIX(mid); case 1: smaller = 0; break; case -1: smaller = 1; } } else { rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE " (must be numeric, true, false or nil)", rb_obj_class(v)); } if (smaller) { high = mid; } else { low = mid + 1; } } if (!satisfied) return Qnil; return INT2FIX(low); }
#clear ⇒ self
Removes all elements from self
; returns self
:
a = [:foo, 'bar', 2]
a.clear # => []
Related: see Methods for Deleting
.
# File 'array.c', line 4641
VALUE rb_ary_clear(VALUE ary) { rb_ary_modify_check(ary); if (ARY_SHARED_P(ary)) { rb_ary_unshare(ary); FL_SET_EMBED(ary); ARY_SET_EMBED_LEN(ary, 0); } else { ARY_SET_LEN(ary, 0); if (ARY_DEFAULT_SIZE * 2 < ARY_CAPA(ary)) { ary_resize_capa(ary, ARY_DEFAULT_SIZE * 2); } } ary_verify(ary); return ary; }
#collect {|element| ... } ⇒ Array
#collect ⇒ Enumerator
#map {|element| ... } ⇒ Array
#map ⇒ Enumerator
Array
#collect ⇒ Enumerator
#map {|element| ... } ⇒ Array
#map ⇒ Enumerator
Alias for #map.
#collect! {|element| ... } ⇒ Array
#collect! ⇒ Enumerator
#map! {|element| ... } ⇒ Array
#map! ⇒ Enumerator
Array
#collect! ⇒ Enumerator
#map! {|element| ... } ⇒ Array
#map! ⇒ Enumerator
Alias for #map!.
#combination(n) {|element| ... } ⇒ self
#combination(n) ⇒ Enumerator
self
#combination(n) ⇒ Enumerator
When a block and a positive integer-convertible object
argument n
(0 < n <= self.size
) are given, calls the block with all n
-tuple combinations of self
; returns self
:
a = %w[a b c] # => ["a", "b", "c"]
a.combination(2) {|combination| p combination } # => ["a", "b", "c"]
Output:
["a", "b"]
["a", "c"]
["b", "c"]
The order of the yielded combinations is not guaranteed.
When n
is zero, calls the block once with a new empty array:
a.combination(0) {|combination| p combination }
[].combination(0) {|combination| p combination }
Output:
[]
[]
When n
is negative or larger than self.size
and self
is non-empty, does not call the block:
a.combination(-1) {|combination| fail 'Cannot happen' } # => ["a", "b", "c"]
a.combination(4) {|combination| fail 'Cannot happen' } # => ["a", "b", "c"]
With no block given, returns a new ::Enumerator
.
Related: Array#permutation;
see also Methods for Iterating
.
# File 'array.c', line 7125
static VALUE rb_ary_combination(VALUE ary, VALUE num) { long i, n, len; n = NUM2LONG(num); RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_combination_size); len = RARRAY_LEN(ary); if (n < 0 || len < n) { /* yield nothing */ } else if (n == 0) { rb_yield(rb_ary_new2(0)); } else if (n == 1) { for (i = 0; i < RARRAY_LEN(ary); i++) { rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i))); } } else { VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ volatile VALUE t0; long *stack = ALLOCV_N(long, t0, n+1); RBASIC_CLEAR_CLASS(ary0); combinate0(len, n, stack, ary0); ALLOCV_END(t0); RBASIC_SET_CLASS_RAW(ary0, rb_cArray); } return ary; }
#compact ⇒ Array
Returns a new array containing only the non-nil
elements from self
; element order is preserved:
a = [nil, 0, nil, false, nil, '', nil, [], nil, {}]
a.compact # => [0, false, "", [], {}]
Related: Array#compact!;
see also Methods for Deleting
.
# File 'array.c', line 6346
static VALUE rb_ary_compact(VALUE ary) { ary = rb_ary_dup(ary); rb_ary_compact_bang(ary); return ary; }
#compact! ⇒ self
?
Removes all nil
elements from self
; Returns self
if any elements are removed, nil
otherwise:
a = [nil, 0, nil, false, nil, '', nil, [], nil, {}]
a.compact! # => [0, false, "", [], {}]
a # => [0, false, "", [], {}]
a.compact! # => nil
Related: Array#compact;
see also Methods for Deleting
.
# File 'array.c', line 6309
static VALUE rb_ary_compact_bang(VALUE ary) { VALUE *p, *t, *end; long n; rb_ary_modify(ary); p = t = (VALUE *)RARRAY_CONST_PTR(ary); /* WB: no new reference */ end = p + RARRAY_LEN(ary); while (t < end) { if (NIL_P(*t)) t++; else *p++ = *t++; } n = p - RARRAY_CONST_PTR(ary); if (RARRAY_LEN(ary) == n) { return Qnil; } ary_resize_smaller(ary, n); return ary; }
#concat(*other_arrays) ⇒ self
Adds to self
all elements from each array in other_arrays
; returns self
:
a = [0, 1]
a.concat(['two', 'three'], [:four, :five], a)
# => [0, 1, "two", "three", :four, :five, 0, 1]
Related: see Methods for Assigning
.
# File 'array.c', line 4959
static VALUE rb_ary_concat_multi(int argc, VALUE *argv, VALUE ary) { rb_ary_modify_check(ary); if (argc == 1) { rb_ary_concat(ary, argv[0]); } else if (argc > 1) { int i; VALUE args = rb_ary_hidden_new(argc); for (i = 0; i < argc; i++) { rb_ary_concat(args, argv[i]); } ary_append(ary, args); } ary_verify(ary); return ary; }
Returns a count of specified elements.
With no argument and no block, returns the count of all elements:
[0, :one, 'two', 3, 3.0].count # => 5
With argument object
given, returns the count of elements #== to object
:
[0, :one, 'two', 3, 3.0].count(3) # => 2
With no argument and a block given, calls the block with each element; returns the count of elements for which the block returns a truthy value:
[0, 1, 2, 3].count {|element| element > 1 } # => 2
With argument object
and a block given, issues a warning, ignores the block, and returns the count of elements #== to object
.
Related: see Methods for Querying
.
# File 'array.c', line 6381
static VALUE rb_ary_count(int argc, VALUE *argv, VALUE ary) { long i, n = 0; if (rb_check_arity(argc, 0, 1) == 0) { VALUE v; if (!rb_block_given_p()) return LONG2NUM(RARRAY_LEN(ary)); for (i = 0; i < RARRAY_LEN(ary); i++) { v = RARRAY_AREF(ary, i); if (RTEST(rb_yield(v))) n++; } } else { VALUE obj = argv[0]; if (rb_block_given_p()) { rb_warn("given block not used"); } for (i = 0; i < RARRAY_LEN(ary); i++) { if (rb_equal(RARRAY_AREF(ary, i), obj)) n++; } } return LONG2NUM(n); }
#cycle(count = nil) {|element| ... } ⇒ nil
#cycle(count = nil) ⇒ Enumerator
nil
#cycle(count = nil) ⇒ Enumerator
With a block given, may call the block, depending on the value of argument #count; #count must be an integer-convertible object
, or nil
.
When #count is positive, calls the block with each element, then does so repeatedly, until it has done so #count times; returns nil
:
output = []
[0, 1].cycle(2) {|element| output.push(element) } # => nil
output # => [0, 1, 0, 1]
When #count is zero or negative, does not call the block:
[0, 1].cycle(0) {|element| fail 'Cannot happen' } # => nil
[0, 1].cycle(-1) {|element| fail 'Cannot happen' } # => nil
When #count is nil
, cycles forever:
# Prints 0 and 1 forever.
[0, 1].cycle {|element| puts element }
[0, 1].cycle(nil) {|element| puts element }
With no block given, returns a new ::Enumerator
.
Related: see Methods for Iterating
.
# File 'array.c', line 6831
static VALUE rb_ary_cycle(int argc, VALUE *argv, VALUE ary) { long n, i; rb_check_arity(argc, 0, 1); RETURN_SIZED_ENUMERATOR(ary, argc, argv, rb_ary_cycle_size); if (argc == 0 || NIL_P(argv[0])) { n = -1; } else { n = NUM2LONG(argv[0]); if (n <= 0) return Qnil; } while (RARRAY_LEN(ary) > 0 && (n < 0 || 0 < n--)) { for (i=0; i<RARRAY_LEN(ary); i++) { rb_yield(RARRAY_AREF(ary, i)); } } return Qnil; }
#deconstruct
# File 'array.c', line 8123
static VALUE rb_ary_deconstruct(VALUE ary) { return ary; }
#delete(object) ⇒ last_removed_object
#delete(object) {|element| ... } ⇒ last_removed_object
, block_return
last_removed_object
#delete(object) {|element| ... } ⇒ last_removed_object
, block_return
Removes zero or more elements from self
.
With no block given, removes from self
each element ele
such that ele == object
; returns the last removed element:
a = [0, 1, 2, 2.0]
a.delete(2) # => 2.0
a # => [0, 1]
Returns nil
if no elements removed:
a.delete(2) # => nil
With a block given, removes from self
each element ele
such that ele == object
.
If any such elements are found, ignores the block and returns the last removed element:
a = [0, 1, 2, 2.0]
a.delete(2) {|element| fail 'Cannot happen' } # => 2.0
a # => [0, 1]
If no such element is found, returns the block’s return value:
a.delete(2) {|element| "Element #{element} not found." }
# => "Element 2 not found."
Related: see Methods for Deleting
.
# File 'array.c', line 3990
VALUE rb_ary_delete(VALUE ary, VALUE item) { VALUE v = item; long i1, i2; for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) { VALUE e = RARRAY_AREF(ary, i1); if (rb_equal(e, item)) { v = e; continue; } if (i1 != i2) { rb_ary_store(ary, i2, e); } i2++; } if (RARRAY_LEN(ary) == i2) { if (rb_block_given_p()) { return rb_yield(item); } return Qnil; } ary_resize_smaller(ary, i2); ary_verify(ary); return v; }
#delete_at(index) ⇒ removed_object
?
Removes the element of self
at the given #index, which must be an integer-convertible object
.
When #index is non-negative, deletes the element at offset #index:
a = [:foo, 'bar', 2]
a.delete_at(1) # => "bar"
a # => [:foo, 2]
When #index is negative, counts backward from the end of the array:
a = [:foo, 'bar', 2]
a.delete_at(-2) # => "bar"
a # => [:foo, 2]
When #index is out of range, returns nil
.
a = [:foo, 'bar', 2]
a.delete_at(3) # => nil
a.delete_at(-4) # => nil
Related: see Methods for Deleting
.
# File 'array.c', line 4094
static VALUE rb_ary_delete_at_m(VALUE ary, VALUE pos) { return rb_ary_delete_at(ary, NUM2LONG(pos)); }
#delete_if {|element| ... } ⇒ self
#delete_if ⇒ new_numerator
self
#delete_if ⇒ new_numerator
With a block given, calls the block with each element of self
; removes the element if the block returns a truthy value; returns self
:
a = [:foo, 'bar', 2, 'bat']
a.delete_if {|element| element.to_s.start_with?('b') } # => [:foo, 2]
With no block given, returns a new ::Enumerator
.
Related: see Methods for Deleting
.
# File 'array.c', line 4371
static VALUE rb_ary_delete_if(VALUE ary) { ary_verify(ary); RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); ary_reject_bang(ary); return ary; }
#difference(*other_arrays = []) ⇒ Array
Returns a new array containing only those elements from self
that are not found in any of the given other_arrays
; items are compared using #eql?; order from self
is preserved:
[0, 1, 1, 2, 1, 1, 3, 1, 1].difference([1]) # => [0, 2, 3]
[0, 1, 2, 3].difference([3, 0], [1, 3]) # => [2]
[0, 1, 2].difference([4]) # => [0, 1, 2]
[0, 1, 2].difference # => [0, 1, 2]
Returns a copy of self
if no arguments are given.
Related: Array#-;
see also Methods for Combining
.
# File 'array.c', line 5498
static VALUE rb_ary_difference_multi(int argc, VALUE *argv, VALUE ary) { VALUE ary_diff; long i, length; volatile VALUE t0; bool *is_hash = ALLOCV_N(bool, t0, argc); ary_diff = rb_ary_new(); length = RARRAY_LEN(ary); for (i = 0; i < argc; i++) { argv[i] = to_ary(argv[i]); is_hash[i] = (length > SMALL_ARRAY_LEN && RARRAY_LEN(argv[i]) > SMALL_ARRAY_LEN); if (is_hash[i]) argv[i] = ary_make_hash(argv[i]); } for (i = 0; i < RARRAY_LEN(ary); i++) { int j; VALUE elt = rb_ary_elt(ary, i); for (j = 0; j < argc; j++) { if (is_hash[j]) { if (rb_hash_stlike_lookup(argv[j], RARRAY_AREF(ary, i), NULL)) break; } else { if (rb_ary_includes_by_eql(argv[j], elt)) break; } } if (j == argc) rb_ary_push(ary_diff, elt); } ALLOCV_END(t0); return ary_diff; }
#dig(index, *identifiers) ⇒ Object
Finds and returns the object in nested object specified by #index and identifiers
; the nested objects may be instances of various classes. See Dig Methods
.
Examples:
a = [:foo, [:, :baz, [:bat, :bam]]]
a.dig(1) # => [:bar, :baz, [:bat, :bam]]
a.dig(1, 2) # => [:bat, :bam]
a.dig(1, 2, 0) # => :bat
a.dig(1, 2, 3) # => nil
Related: see Methods for Fetching
.
# File 'array.c', line 7940
static VALUE rb_ary_dig(int argc, VALUE *argv, VALUE self) { rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS); self = rb_ary_at(self, *argv); if (!--argc) return self; ++argv; return rb_obj_dig(argc, argv, self, Qnil); }
#drop(n) ⇒ Array
Returns a new array containing all but the first n
element of self
, where n
is a non-negative Integer; does not modify self
.
Examples:
a = [0, 1, 2, 3, 4, 5]
a.drop(0) # => [0, 1, 2, 3, 4, 5]
a.drop(1) # => [1, 2, 3, 4, 5]
a.drop(2) # => [2, 3, 4, 5]
a.drop(9) # => []
Related: see Methods for Fetching
.
# File 'array.c', line 7607
static VALUE rb_ary_drop(VALUE ary, VALUE n) { VALUE result; long pos = NUM2LONG(n); if (pos < 0) { rb_raise(rb_eArgError, "attempt to drop negative size"); } result = rb_ary_subseq(ary, pos, RARRAY_LEN(ary)); if (NIL_P(result)) result = rb_ary_new(); return result; }
#drop_while {|element| ... } ⇒ Array
#drop_while ⇒ Enumerator
Array
#drop_while ⇒ Enumerator
With a block given, calls the block with each successive element of self
; stops if the block returns false
or nil
; returns a new array omitting those elements for which the block returned a truthy value; does not modify self
:
a = [0, 1, 2, 3, 4, 5]
a.drop_while {|element| element < 3 } # => [3, 4, 5]
With no block given, returns a new ::Enumerator
.
Related: see Methods for Fetching
.
# File 'array.c', line 7639
static VALUE rb_ary_drop_while(VALUE ary) { long i; RETURN_ENUMERATOR(ary, 0, 0); for (i = 0; i < RARRAY_LEN(ary); i++) { if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break; } return rb_ary_drop(ary, LONG2FIX(i)); }
#each {|element| ... } ⇒ self
#each ⇒ Enumerator
self
#each ⇒ Enumerator
With a block given, iterates over the elements of self
, passing each element to the block; returns self
:
a = [:foo, 'bar', 2]
a.each {|element| puts "#{element.class} #{element}" }
Output:
Symbol foo
String
Integer 2
Allows the array to be modified during iteration:
a = [:foo, 'bar', 2]
a.each {|element| puts element; a.clear if element.to_s.start_with?('b') }
Output:
foo
With no block given, returns a new ::Enumerator
.
Related: see Methods for Iterating
.
# File 'array.c', line 2640
VALUE rb_ary_each(VALUE ary) { long i; ary_verify(ary); RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); for (i=0; i<RARRAY_LEN(ary); i++) { rb_yield(RARRAY_AREF(ary, i)); } return ary; }
#each_index {|index| ... } ⇒ self
#each_index ⇒ Enumerator
self
#each_index ⇒ Enumerator
With a block given, iterates over the elements of self
, passing each array index to the block; returns self
:
a = [:foo, 'bar', 2]
a.each_index {|index| puts "#{index} #{a[index]}" }
Output:
0 foo
1
2 2
Allows the array to be modified during iteration:
a = [:foo, 'bar', 2]
a.each_index {|index| puts index; a.clear if index > 0 }
a # => []
Output:
0
1
With no block given, returns a new ::Enumerator
.
Related: see Methods for Iterating
.
# File 'array.c', line 2686
static VALUE rb_ary_each_index(VALUE ary) { long i; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); for (i=0; i<RARRAY_LEN(ary); i++) { rb_yield(LONG2NUM(i)); } return ary; }
#eql?(other_array) ⇒ Boolean
Returns true
if self
and other_array
are the same size, and if, for each index i
in self
, self[i].eql?(other_array[i])
:
a0 = [:foo, 'bar', 2]
a1 = [:foo, 'bar', 2]
a1.eql?(a0) # => true
Otherwise, returns false
.
This method is different from method #==, which compares using method Object#==
.
Related: see Methods for Querying
.
# File 'array.c', line 5217
static VALUE rb_ary_eql(VALUE ary1, VALUE ary2) { if (ary1 == ary2) return Qtrue; if (!RB_TYPE_P(ary2, T_ARRAY)) return Qfalse; if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse; if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue; return rb_exec_recursive_paired(recursive_eql, ary1, ary2, ary2); }
#fetch(index) ⇒ element
#fetch(index, default_value) ⇒ element
, default_value
#fetch(index) {|index| ... } ⇒ element
, block_return_value
element
#fetch(index, default_value) ⇒ element
, default_value
#fetch(index) {|index| ... } ⇒ element
, block_return_value
Returns the element of self
at offset #index if #index is in range; #index must be an integer-convertible object
.
With the single argument #index and no block, returns the element at offset #index:
a = [:foo, 'bar', 2]
a.fetch(1) # => "bar"
a.fetch(1.1) # => "bar"
If #index is negative, counts from the end of the array:
a = [:foo, 'bar', 2]
a.fetch(-1) # => 2
a.fetch(-2) # => "bar"
With arguments #index and default_value
(which may be any object) and no block, returns default_value
if #index is out-of-range:
a = [:foo, 'bar', 2]
a.fetch(1, nil) # => "bar"
a.fetch(3, :foo) # => :foo
With argument #index and a block, returns the element at offset #index if index is in range (and the block is not called); otherwise calls the block with index and returns its return value:
a = [:foo, 'bar', 2]
a.fetch(1) {|index| raise 'Cannot happen' } # => "bar"
a.fetch(50) {|index| "Value for #{index}" } # => "Value for 50"
Related: see Methods for Fetching
.
# File 'array.c', line 2045
static VALUE rb_ary_fetch(int argc, VALUE *argv, VALUE ary) { VALUE pos, ifnone; long block_given; long idx; rb_scan_args(argc, argv, "11", &pos, &ifnone); block_given = rb_block_given_p(); if (block_given && argc == 2) { rb_warn("block supersedes default value argument"); } idx = NUM2LONG(pos); if (idx < 0) { idx += RARRAY_LEN(ary); } if (idx < 0 || RARRAY_LEN(ary) <= idx) { if (block_given) return rb_yield(pos); if (argc == 1) { rb_raise(rb_eIndexError, "index %ld outside of array bounds: %ld...%ld", idx - (idx < 0 ? RARRAY_LEN(ary) : 0), -RARRAY_LEN(ary), RARRAY_LEN(ary)); } return ifnone; } return RARRAY_AREF(ary, idx); }
#fetch_values(*indexes) ⇒ Array
#fetch_values(*indexes) {|index| ... } ⇒ Array
Array
#fetch_values(*indexes) {|index| ... } ⇒ Array
With no block given, returns a new array containing the elements of self
at the offsets given by indexes
; each of the indexes
must be an integer-convertible object
:
a = [:foo, :, :baz]
a.fetch_values(3, 1) # => [:baz, :foo]
a.fetch_values(3.1, 1) # => [:baz, :foo]
a.fetch_values # => []
For a negative index, counts backwards from the end of the array:
a.fetch_values([-2, -1]) # [:bar, :baz]
When no block is given, raises an exception if any index is out of range.
With a block given, for each index:
-
If the index in in range, uses an element of
self
(as above). -
Otherwise calls, the block with the index, and uses the block’s return value.
Example:
a = [:foo, :, :baz]
a.fetch_values(1, 0, 42, 777) {|index| index.to_s}
# => [:bar, :foo, "42", "777"]
Related: see Methods for Fetching
.
#fill(object, start = nil, count = nil) ⇒ Array
#fill(object, range) ⇒ Array
#fill(start = nil, count = nil) {|element| ... } ⇒ Array
#fill(range) {|element| ... } ⇒ Array
Array
#fill(object, range) ⇒ Array
#fill(start = nil, count = nil) {|element| ... } ⇒ Array
#fill(range) {|element| ... } ⇒ Array
Replaces selected elements in self
; may add elements to self
; always returns self
(never a new array).
In brief:
# Non-negative start.
['a', 'b', 'c', 'd'].fill('-', 1, 2) # => ["a", "-", "-", "d"]
['a', 'b', 'c', 'd'].fill(1, 2) {|e| e.to_s } # => ["a", "1", "2", "d"]
# Extends with specified values if necessary.
['a', 'b', 'c', 'd'].fill('-', 3, 2) # => ["a", "b", "c", "-", "-"]
['a', 'b', 'c', 'd'].fill(3, 2) {|e| e.to_s } # => ["a", "b", "c", "3", "4"]
# Fills with nils if necessary.
['a', 'b', 'c', 'd'].fill('-', 6, 2) # => ["a", "b", "c", "d", nil, nil, "-", "-"]
['a', 'b', 'c', 'd'].fill(6, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, nil, "6", "7"]
# For negative start, counts backwards from the end.
['a', 'b', 'c', 'd'].fill('-', -3, 3) # => ["a", "-", "-", "-"]
['a', 'b', 'c', 'd'].fill(-3, 3) {|e| e.to_s } # => ["a", "1", "2", "3"]
# Range.
['a', 'b', 'c', 'd'].fill('-', 1..2) # => ["a", "-", "-", "d"]
['a', 'b', 'c', 'd'].fill(1..2) {|e| e.to_s } # => ["a", "1", "2", "d"]
When arguments start
and #count are given, they select the elements of self
to be replaced; each must be an integer-convertible object
(or nil
):
-
start
specifies the zero-based offset of the first element to be replaced;nil
means zero. -
#count is the number of consecutive elements to be replaced;
nil
means “all the rest.”
With argument object
given, that one object is used for all replacements:
o = Object.new # => #<Object:0x0000014e7bff7600>
a = ['a', 'b', 'c', 'd'] # => ["a", "b", "c", "d"]
a.fill(o, 1, 2)
# => ["a", #<Object:0x0000014e7bff7600>, #<Object:0x0000014e7bff7600>, "d"]
With a block given, the block is called once for each element to be replaced; the value passed to the block is the index of the element to be replaced (not the element itself); the block’s return value replaces the element:
a = ['a', 'b', 'c', 'd'] # => ["a", "b", "c", "d"]
a.fill(1, 2) {|element| element.to_s } # => ["a", "1", "2", "d"]
For arguments start
and #count:
-
If
start
is non-negative, replaces #count elements beginning at offsetstart
:['a', 'b', 'c', 'd'].fill('-', 0, 2) # => ["-", "-", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', 1, 2) # => ["a", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill('-', 2, 2) # => ["a", "b", "-", "-"] ['a', 'b', 'c', 'd'].fill(0, 2) {|e| e.to_s } # => ["0", "1", "c", "d"] ['a', 'b', 'c', 'd'].fill(1, 2) {|e| e.to_s } # => ["a", "1", "2", "d"] ['a', 'b', 'c', 'd'].fill(2, 2) {|e| e.to_s } # => ["a", "b", "2", "3"]
Extends
self
if necessary:['a', 'b', 'c', 'd'].fill('-', 3, 2) # => ["a", "b", "c", "-", "-"] ['a', 'b', 'c', 'd'].fill('-', 4, 2) # => ["a", "b", "c", "d", "-", "-"] ['a', 'b', 'c', 'd'].fill(3, 2) {|e| e.to_s } # => ["a", "b", "c", "3", "4"] ['a', 'b', 'c', 'd'].fill(4, 2) {|e| e.to_s } # => ["a", "b", "c", "d", "4", "5"]
Fills with
nil
if necessary:['a', 'b', 'c', 'd'].fill('-', 5, 2) # => ["a", "b", "c", "d", nil, "-", "-"] ['a', 'b', 'c', 'd'].fill('-', 6, 2) # => ["a", "b", "c", "d", nil, nil, "-", "-"] ['a', 'b', 'c', 'd'].fill(5, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, "5", "6"] ['a', 'b', 'c', 'd'].fill(6, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, nil, "6", "7"]
Does nothing if #count is non-positive:
['a', 'b', 'c', 'd'].fill('-', 2, 0) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', 2, -100) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', 6, -100) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(2, 0) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(2, -100) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(6, -100) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
-
If
start
is negative, counts backwards from the end ofself
:['a', 'b', 'c', 'd'].fill('-', -4, 3) # => ["-", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill('-', -3, 3) # => ["a", "-", "-", "-"] ['a', 'b', 'c', 'd'].fill(-4, 3) {|e| e.to_s } # => ["0", "1", "2", "d"] ['a', 'b', 'c', 'd'].fill(-3, 3) {|e| e.to_s } # => ["a", "1", "2", "3"]
Extends
self
if necessary:['a', 'b', 'c', 'd'].fill('-', -2, 3) # => ["a", "b", "-", "-", "-"] ['a', 'b', 'c', 'd'].fill('-', -1, 3) # => ["a", "b", "c", "-", "-", "-"] ['a', 'b', 'c', 'd'].fill(-2, 3) {|e| e.to_s } # => ["a", "b", "2", "3", "4"] ['a', 'b', 'c', 'd'].fill(-1, 3) {|e| e.to_s } # => ["a", "b", "c", "3", "4", "5"]
Starts at the beginning of
self
ifstart
is negative and out-of-range:['a', 'b', 'c', 'd'].fill('-', -5, 2) # => ["-", "-", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', -6, 2) # => ["-", "-", "c", "d"] ['a', 'b', 'c', 'd'].fill(-5, 2) {|e| e.to_s } # => ["0", "1", "c", "d"] ['a', 'b', 'c', 'd'].fill(-6, 2) {|e| e.to_s } # => ["0", "1", "c", "d"]
Does nothing if #count is non-positive:
['a', 'b', 'c', 'd'].fill('-', -2, 0) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', -2, -1) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(-2, 0) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(-2, -1) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
When argument range
is given, it must be a ::Range
object whose members are numeric; its begin
and end
values determine the elements of self
to be replaced:
-
If both
begin
andend
are positive, they specify the first and last elements to be replaced:['a', 'b', 'c', 'd'].fill('-', 1..2) # => ["a", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill(1..2) {|e| e.to_s } # => ["a", "1", "2", "d"]
If
end
is smaller thanbegin
, replaces no elements:['a', 'b', 'c', 'd'].fill('-', 2..1) # => ["a", "b", "c", "d"] ['a', 'b', 'c', 'd'].fill(2..1) {|e| e.to_s } # => ["a", "b", "c", "d"]
-
If either is negative (or both are negative), counts backwards from the end of
self
:['a', 'b', 'c', 'd'].fill('-', -3..2) # => ["a", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill('-', 1..-2) # => ["a", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill('-', -3..-2) # => ["a", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill(-3..2) {|e| e.to_s } # => ["a", "1", "2", "d"] ['a', 'b', 'c', 'd'].fill(1..-2) {|e| e.to_s } # => ["a", "1", "2", "d"] ['a', 'b', 'c', 'd'].fill(-3..-2) {|e| e.to_s } # => ["a", "1", "2", "d"]
-
If the
end
value is excluded (see Range#exclude_end?), omits the last replacement:['a', 'b', 'c', 'd'].fill('-', 1...2) # => ["a", "-", "c", "d"] ['a', 'b', 'c', 'd'].fill('-', 1...-2) # => ["a", "-", "c", "d"] ['a', 'b', 'c', 'd'].fill(1...2) {|e| e.to_s } # => ["a", "1", "c", "d"] ['a', 'b', 'c', 'd'].fill(1...-2) {|e| e.to_s } # => ["a", "1", "c", "d"]
-
If the range is endless (see
Endless Ranges
), replaces elements to the end ofself
:['a', 'b', 'c', 'd'].fill('-', 1..) # => ["a", "-", "-", "-"] ['a', 'b', 'c', 'd'].fill(1..) {|e| e.to_s } # => ["a", "1", "2", "3"]
-
If the range is beginless (see
Beginless Ranges
), replaces elements from the beginning ofself
:['a', 'b', 'c', 'd'].fill('-', ..2) # => ["-", "-", "-", "d"] ['a', 'b', 'c', 'd'].fill(..2) {|e| e.to_s } # => ["0", "1", "2", "d"]
Related: see Methods for Assigning
.
# File 'array.c', line 4840
static VALUE rb_ary_fill(int argc, VALUE *argv, VALUE ary) { VALUE item = Qundef, arg1, arg2; long beg = 0, end = 0, len = 0; if (rb_block_given_p()) { rb_scan_args(argc, argv, "02", &arg1, &arg2); argc += 1; /* hackish */ } else { rb_scan_args(argc, argv, "12", &item, &arg1, &arg2); } switch (argc) { case 1: beg = 0; len = RARRAY_LEN(ary); break; case 2: if (rb_range_beg_len(arg1, &beg, &len, RARRAY_LEN(ary), 1)) { break; } /* fall through */ case 3: beg = NIL_P(arg1) ? 0 : NUM2LONG(arg1); if (beg < 0) { beg = RARRAY_LEN(ary) + beg; if (beg < 0) beg = 0; } len = NIL_P(arg2) ? RARRAY_LEN(ary) - beg : NUM2LONG(arg2); break; } rb_ary_modify(ary); if (len < 0) { return ary; } if (beg >= ARY_MAX_SIZE || len > ARY_MAX_SIZE - beg) { rb_raise(rb_eArgError, "argument too big"); } end = beg + len; if (RARRAY_LEN(ary) < end) { if (end >= ARY_CAPA(ary)) { ary_resize_capa(ary, end); } ary_mem_clear(ary, RARRAY_LEN(ary), end - RARRAY_LEN(ary)); ARY_SET_LEN(ary, end); } if (UNDEF_P(item)) { VALUE v; long i; for (i=beg; i<end; i++) { v = rb_yield(LONG2NUM(i)); if (i>=RARRAY_LEN(ary)) break; ARY_SET(ary, i, v); } } else { ary_memfill(ary, beg, len, item); } return ary; }
#select {|element| ... } ⇒ Array
#select ⇒ Enumerator
#filter {|element| ... } ⇒ Array
#filter ⇒ Enumerator
Also known as: #select
Array
#select ⇒ Enumerator
#filter {|element| ... } ⇒ Array
#filter ⇒ Enumerator
With a block given, calls the block with each element of self
; returns a new array containing those elements of self
for which the block returns a truthy value:
a = [:foo, 'bar', 2, :bam]
a.select {|element| element.to_s.start_with?('b') }
# => ["bar", :bam]
With no block given, returns a new ::Enumerator
.
Related: see Methods for Fetching
.
# File 'array.c', line 3820
static VALUE rb_ary_select(VALUE ary) { VALUE result; long i; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); result = rb_ary_new2(RARRAY_LEN(ary)); for (i = 0; i < RARRAY_LEN(ary); i++) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) { rb_ary_push(result, rb_ary_elt(ary, i)); } } return result; }
#select! {|element| ... } ⇒ self
?
#select! ⇒ Enumerator
#filter! {|element| ... } ⇒ self
?
#filter! ⇒ Enumerator
Also known as: #select!
self
?
#select! ⇒ Enumerator
#filter! {|element| ... } ⇒ self
?
#filter! ⇒ Enumerator
With a block given, calls the block with each element of self
; removes from self
those elements for which the block returns false
or nil
.
Returns self
if any elements were removed:
a = [:foo, 'bar', 2, :bam]
a.select! {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
Returns nil
if no elements were removed.
With no block given, returns a new ::Enumerator
.
Related: see Methods for Deleting
.
# File 'array.c', line 3903
static VALUE rb_ary_select_bang(VALUE ary) { struct select_bang_arg args; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rb_ary_modify(ary); args.ary = ary; args.len[0] = args.len[1] = 0; return rb_ensure(select_bang_i, (VALUE)&args, select_bang_ensure, (VALUE)&args); }
#find_index(object) ⇒ Integer?
#find_index {|element| ... } ⇒ Integer?
#find_index ⇒ Enumerator
#index(object) ⇒ Integer?
#index {|element| ... } ⇒ Integer?
#index ⇒ Enumerator
Alias for #index.
#first ⇒ Object?
#first(count) ⇒ Array
Array
Returns elements from self
, or nil
; does not modify self
.
With no argument given, returns the first element (if available):
a = [:foo, 'bar', 2]
a.first # => :foo
a # => [:foo, "bar", 2]
If self
is empty, returns nil
.
[].first # => nil
With non-negative integer argument #count given, returns the first #count elements (as available) in a new array:
a.first(0) # => []
a.first(2) # => [:foo, "bar"]
a.first(50) # => [:foo, "bar", 2]
Related: see Methods for Querying
.
# File 'array.rb', line 130
def first n = unspecified = true if Primitive.mandatory_only? Primitive.attr! :leaf Primitive.cexpr! %q{ ary_first(self) } else if unspecified Primitive.cexpr! %q{ ary_first(self) } else Primitive.cexpr! %q{ ary_take_first_or_last_n(self, NUM2LONG(n), ARY_TAKE_FIRST) } end end end
#flatten(depth = nil) ⇒ Array
Returns a new array that is a recursive flattening of self
to depth
levels of recursion; depth
must be an integer-convertible object
or nil
. At each level of recursion:
-
Each element that is an array is “flattened” (that is, replaced by its individual array elements).
-
Each element that is not an array is unchanged (even if the element is an object that has instance method
flatten
).
With non-negative integer argument depth
, flattens recursively through depth
levels:
a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
a # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(0) # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(1 ) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(2) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(3) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
With nil
or negative depth
, flattens all levels.
a.flatten # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.flatten(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
Related: Array#flatten!;
see also Methods for Converting
.
# File 'array.c', line 6588
static VALUE rb_ary_flatten(int argc, VALUE *argv, VALUE ary) { int level = -1; VALUE result; if (rb_check_arity(argc, 0, 1) && !NIL_P(argv[0])) { level = NUM2INT(argv[0]); if (level == 0) return ary_make_shared_copy(ary); } result = flatten(ary, level); if (result == ary) { result = ary_make_shared_copy(ary); } return result; }
#flatten!(depth = nil) ⇒ self
?
Returns self
as a recursively flattening of self
to depth
levels of recursion; depth
must be an integer-convertible object
, or nil
. At each level of recursion:
-
Each element that is an array is “flattened” (that is, replaced by its individual array elements).
-
Each element that is not an array is unchanged (even if the element is an object that has instance method #flatten).
Returns nil
if no elements were flattened.
With non-negative integer argument depth
, flattens recursively through depth
levels:
a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
a # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
a.dup.flatten!(1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.dup.flatten!(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.dup.flatten!(2) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.dup.flatten!(3) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
With nil
or negative argument depth
, flattens all levels:
a.dup.flatten! # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
a.dup.flatten!(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
Related: Array#flatten;
see also Methods for Assigning
.
# File 'array.c', line 6531
static VALUE rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary) { int mod = 0, level = -1; VALUE result, lv; lv = (rb_check_arity(argc, 0, 1) ? argv[0] : Qnil); rb_ary_modify_check(ary); if (!NIL_P(lv)) level = NUM2INT(lv); if (level == 0) return Qnil; result = flatten(ary, level); if (result == ary) { return Qnil; } if (!(mod = ARY_EMBED_P(result))) rb_ary_freeze(result); rb_ary_replace(ary, result); if (mod) ARY_SET_EMBED_LEN(result, 0); return ary; }
#freeze ⇒ self
Freezes self
(if not already frozen); returns self
:
a = []
a.frozen? # => false
a.freeze
a.frozen? # => true
No further changes may be made to self
; raises ::FrozenError
if a change is attempted.
Related: Object#frozen?
.
# File 'array.c', line 647
VALUE rb_ary_freeze(VALUE ary) { RUBY_ASSERT(RB_TYPE_P(ary, T_ARRAY)); if (OBJ_FROZEN(ary)) return ary; if (!ARY_EMBED_P(ary) && !ARY_SHARED_P(ary) && !ARY_SHARED_ROOT_P(ary)) { ary_shrink_capa(ary); } return rb_obj_freeze(ary); }
#hash ⇒ Integer
Returns the integer hash value for self
.
Two arrays with the same content will have the same hash value (and will compare using eql?):
['a', 'b'].hash == ['a', 'b'].hash # => true
['a', 'b'].hash == ['a', 'c'].hash # => false
['a', 'b'].hash == ['a'].hash # => false
# File 'array.c', line 5259
static VALUE rb_ary_hash(VALUE ary) { return rb_ary_hash_values(RARRAY_LEN(ary), RARRAY_CONST_PTR(ary)); }
#include?(object) ⇒ Boolean
Returns whether for some element element
in self
, object == element
:
[0, 1, 2].include?(2) # => true
[0, 1, 2].include?(2.0) # => true
[0, 1, 2].include?(2.1) # => false
Related: see Methods for Querying
.
# File 'array.c', line 5279
VALUE rb_ary_includes(VALUE ary, VALUE item) { long i; VALUE e; for (i=0; i<RARRAY_LEN(ary); i++) { e = RARRAY_AREF(ary, i); if (rb_equal(e, item)) { return Qtrue; } } return Qfalse; }
#find_index(object) ⇒ Integer?
#find_index {|element| ... } ⇒ Integer?
#find_index ⇒ Enumerator
#index(object) ⇒ Integer?
#index {|element| ... } ⇒ Integer?
#index ⇒ Enumerator
Also known as: #find_index
Returns the zero-based integer index of a specified element, or nil
.
With only argument object
given, returns the index of the first element element
for which object == element
:
a = [:foo, 'bar', 2, 'bar']
a.index('bar') # => 1
Returns nil
if no such element found.
With only a block given, calls the block with each successive element; returns the index of the first element for which the block returns a truthy value:
a = [:foo, 'bar', 2, 'bar']
a.index {|element| element == 'bar' } # => 1
Returns nil
if the block never returns a truthy value.
With neither an argument nor a block given, returns a new ::Enumerator
.
Related: see Methods for Querying
.
# File 'array.c', line 2107
static VALUE rb_ary_index(int argc, VALUE *argv, VALUE ary) { VALUE val; long i; if (argc == 0) { RETURN_ENUMERATOR(ary, 0, 0); for (i=0; i<RARRAY_LEN(ary); i++) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) { return LONG2NUM(i); } } return Qnil; } rb_check_arity(argc, 0, 1); val = argv[0]; if (rb_block_given_p()) rb_warn("given block not used"); for (i=0; i<RARRAY_LEN(ary); i++) { VALUE e = RARRAY_AREF(ary, i); if (rb_equal(e, val)) { return LONG2NUM(i); } } return Qnil; }
#initialize_copy(other_array) ⇒ self
#replace(other_array) ⇒ self
self
#replace(other_array) ⇒ self
Alias for #replace.
#insert(index, *objects) ⇒ self
Inserts the given objects
as elements of self
; returns self
.
When #index is non-negative, inserts objects
before the element at offset #index:
a = ['a', 'b', 'c'] # => ["a", "b", "c"]
a.insert(1, :x, :y, :z) # => ["a", :x, :y, :z, "b", "c"]
Extends the array if #index is beyond the array (index >= self.size
):
a = ['a', 'b', 'c'] # => ["a", "b", "c"]
a.insert(5, :x, :y, :z) # => ["a", "b", "c", nil, nil, :x, :y, :z]
When #index is negative, inserts objects
after the element at offset index + self.size
:
a = ['a', 'b', 'c'] # => ["a", "b", "c"]
a.insert(-2, :x, :y, :z) # => ["a", "b", :x, :y, :z, "c"]
With no objects
given, does nothing:
a = ['a', 'b', 'c'] # => ["a", "b", "c"]
a.insert(1) # => ["a", "b", "c"]
a.insert(50) # => ["a", "b", "c"]
a.insert(-50) # => ["a", "b", "c"]
Raises IndexError if objects
are given and #index is negative and out of range.
Related: see Methods for Assigning
.
# File 'array.c', line 2560
static VALUE rb_ary_insert(int argc, VALUE *argv, VALUE ary) { long pos; rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS); rb_ary_modify_check(ary); pos = NUM2LONG(argv[0]); if (argc == 1) return ary; if (pos == -1) { pos = RARRAY_LEN(ary); } else if (pos < 0) { long minpos = -RARRAY_LEN(ary) - 1; if (pos < minpos) { rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld", pos, minpos); } pos++; } rb_ary_splice(ary, pos, 0, argv + 1, argc - 1); return ary; }
Alias for #to_s.
#intersect?(other_array) ⇒ Boolean
# File 'array.c', line 5757
static VALUE rb_ary_intersect_p(VALUE ary1, VALUE ary2) { VALUE hash, v, result, shorter, longer; st_data_t vv; long i; ary2 = to_ary(ary2); if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return Qfalse; if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) { for (i=0; i<RARRAY_LEN(ary1); i++) { v = RARRAY_AREF(ary1, i); if (rb_ary_includes_by_eql(ary2, v)) return Qtrue; } return Qfalse; } shorter = ary1; longer = ary2; if (RARRAY_LEN(ary1) > RARRAY_LEN(ary2)) { longer = ary1; shorter = ary2; } hash = ary_make_hash(shorter); result = Qfalse; for (i=0; i<RARRAY_LEN(longer); i++) { v = RARRAY_AREF(longer, i); vv = (st_data_t)v; if (rb_hash_stlike_lookup(hash, vv, 0)) { result = Qtrue; break; } } return result; }
#intersection(*other_arrays) ⇒ Array
Returns a new array containing each element in self
that is #eql? to at least one element in each of the given other_arrays
; duplicates are omitted:
[0, 0, 1, 1, 2, 3].intersection([0, 1, 2], [0, 1, 3]) # => [0, 1]
Each element must correctly implement method #hash.
Order from self
is preserved:
[0, 1, 2].intersection([2, 1, 0]) # => [0, 1, 2]
Returns a copy of self
if no arguments are given.
Related: see Methods for Combining
.
# File 'array.c', line 5614
static VALUE rb_ary_intersection_multi(int argc, VALUE *argv, VALUE ary) { VALUE result = rb_ary_dup(ary); int i; for (i = 0; i < argc; i++) { result = rb_ary_and(result, argv[i]); } return result; }
#join(separator = $,) ⇒ String
Returns the new string formed by joining the converted elements of self
; for each element element
:
-
Converts recursively using
element.join(separator)
ifelement
is akind_of?(Array)
. -
Otherwise, converts using
element.to_s
.
With no argument given, joins using the output field separator, $,
:
a = [:foo, 'bar', 2]
$, # => nil
a.join # => "foobar2"
With string argument separator
given, joins using that separator:
a = [:foo, 'bar', 2]
a.join("\n") # => "foo\nbar\n2"
Joins recursively for nested arrays:
a = [:foo, [:, [:baz, :bat]]]
a.join # => "foobarbazbat"
Related: see Methods for Converting
.
# File 'array.c', line 2958
static VALUE rb_ary_join_m(int argc, VALUE *argv, VALUE ary) { VALUE sep; if (rb_check_arity(argc, 0, 1) == 0 || NIL_P(sep = argv[0])) { sep = rb_output_fs; if (!NIL_P(sep)) { rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "$, is set to non-nil value"); } } return rb_ary_join(ary, sep); }
#keep_if {|element| ... } ⇒ self
#keep_if ⇒ Enumerator
self
#keep_if ⇒ Enumerator
With a block given, calls the block with each element of self
; removes the element from self
if the block does not return a truthy value:
a = [:foo, 'bar', 2, :bam]
a.keep_if {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
With no block given, returns a new ::Enumerator
.
Related: see Methods for Deleting
.
# File 'array.c', line 3932
static VALUE rb_ary_keep_if(VALUE ary) { RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rb_ary_select_bang(ary); return ary; }
#last ⇒ last_object
?
#last(n) ⇒ Array
last_object
?
#last(n) ⇒ Array
Returns elements from self
, or nil
; self
is not modified.
With no argument given, returns the last element, or nil
if self
is empty:
a = [:foo, 'bar', 2]
a.last # => 2
a # => [:foo, "bar", 2]
[].last # => nil
With non-negative integer argument n
is given, returns a new array containing the trailing n
elements of self
, as available:
a = [:foo, 'bar', 2]
a.last(2) # => ["bar", 2]
a.last(50) # => [:foo, "bar", 2]
a.last(0) # => []
[].last(3) # => []
Related: see Methods for Fetching
.
# File 'array.rb', line 167
def last n = unspecified = true if Primitive.mandatory_only? Primitive.attr! :leaf Primitive.cexpr! %q{ ary_last(self) } else if unspecified Primitive.cexpr! %q{ ary_last(self) } else Primitive.cexpr! %q{ ary_take_first_or_last_n(self, NUM2LONG(n), ARY_TAKE_LAST) } end end end
Also known as: #size
Returns the count of elements in self
:
[0, 1, 2].length # => 3
[].length # => 0
Related: see Methods for Querying
.
# File 'array.c', line 2753
static VALUE rb_ary_length(VALUE ary) { long len = RARRAY_LEN(ary); return LONG2NUM(len); }
#collect {|element| ... } ⇒ Array
#collect ⇒ Enumerator
#map {|element| ... } ⇒ Array
#map ⇒ Enumerator
Also known as: #collect
Array
#collect ⇒ Enumerator
#map {|element| ... } ⇒ Array
#map ⇒ Enumerator
With a block given, calls the block with each element of self
; returns a new array whose elements are the return values from the block:
a = [:foo, 'bar', 2]
a1 = a.map {|element| element.class }
a1 # => [Symbol, String, Integer]
With no block given, returns a new ::Enumerator
.
Related: #collect!; see also Methods for Converting
.
# File 'array.c', line 3642
static VALUE rb_ary_collect(VALUE ary) { long i; VALUE collect; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); collect = rb_ary_new2(RARRAY_LEN(ary)); for (i = 0; i < RARRAY_LEN(ary); i++) { rb_ary_push(collect, rb_yield(RARRAY_AREF(ary, i))); } return collect; }
#collect! {|element| ... } ⇒ Array
#collect! ⇒ Enumerator
#map! {|element| ... } ⇒ Array
#map! ⇒ Enumerator
Also known as: #collect!
Array
#collect! ⇒ Enumerator
#map! {|element| ... } ⇒ Array
#map! ⇒ Enumerator
With a block given, calls the block with each element of self
and replaces the element with the block’s return value; returns self
:
a = [:foo, 'bar', 2]
a.map! { |element| element.class } # => [Symbol, String, Integer]
With no block given, returns a new ::Enumerator
.
Related: #collect; see also Methods for Converting
.
# File 'array.c', line 3677
static VALUE rb_ary_collect_bang(VALUE ary) { long i; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rb_ary_modify(ary); for (i = 0; i < RARRAY_LEN(ary); i++) { rb_ary_store(ary, i, rb_yield(RARRAY_AREF(ary, i))); } return ary; }
#max ⇒ element
#max(n) ⇒ Array
#max {|a, b| ... } ⇒ element
#max(n) {|a, b| ... } ⇒ Array
element
#max(n) ⇒ Array
#max {|a, b| ... } ⇒ element
#max(n) {|a, b| ... } ⇒ Array
Returns one of the following:
-
The maximum-valued element from
self
. -
A new array of maximum-valued elements from
self
.
Does not modify self
.
With no block given, each element in self
must respond to method #<=> with a numeric.
With no argument and no block, returns the element in self
having the maximum value per method #<=>:
[1, 0, 3, 2].max # => 3
With non-negative numeric argument n
and no block, returns a new array with at most n
elements, in descending order, per method #<=>:
[1, 0, 3, 2].max(3) # => [3, 2, 1]
[1, 0, 3, 2].max(3.0) # => [3, 2, 1]
[1, 0, 3, 2].max(9) # => [3, 2, 1, 0]
[1, 0, 3, 2].max(0) # => []
With a block given, the block must return a numeric.
With a block and no argument, calls the block self.size - 1
times to compare elements; returns the element having the maximum value per the block:
['0', '', '000', '00'].max {|a, b| a.size <=> b.size }
# => "000"
With non-negative numeric argument n
and a block, returns a new array with at most n
elements, in descending order, per the block:
['0', '', '000', '00'].max(2) {|a, b| a.size <=> b.size }
# => ["000", "00"]
Related: see Methods for Fetching
.
# File 'array.c', line 5934
static VALUE rb_ary_max(int argc, VALUE *argv, VALUE ary) { VALUE result = Qundef, v; VALUE num; long i; if (rb_check_arity(argc, 0, 1) && !NIL_P(num = argv[0])) return rb_nmin_run(ary, num, 0, 1, 1); const long n = RARRAY_LEN(ary); if (rb_block_given_p()) { for (i = 0; i < RARRAY_LEN(ary); i++) { v = RARRAY_AREF(ary, i); if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) > 0) { result = v; } } } else if (n > 0) { result = RARRAY_AREF(ary, 0); if (n > 1) { if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) { return ary_max_opt_fixnum(ary, 1, result); } else if (STRING_P(result) && CMP_OPTIMIZABLE(STRING)) { return ary_max_opt_string(ary, 1, result); } else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(FLOAT)) { return ary_max_opt_float(ary, 1, result); } else { return ary_max_generic(ary, 1, result); } } } if (UNDEF_P(result)) return Qnil; return result; }
#min ⇒ element
#min(n) ⇒ Array
#min {|a, b| ... } ⇒ element
#min(n) {|a, b| ... } ⇒ Array
element
#min(n) ⇒ Array
#min {|a, b| ... } ⇒ element
#min(n) {|a, b| ... } ⇒ Array
Returns one of the following:
-
The minimum-valued element from
self
. -
A new array of minimum-valued elements from
self
.
Does not modify self
.
With no block given, each element in self
must respond to method #<=> with a numeric.
With no argument and no block, returns the element in self
having the minimum value per method #<=>:
[1, 0, 3, 2].min # => 0
With non-negative numeric argument n
and no block, returns a new array with at most n
elements, in ascending order, per method #<=>:
[1, 0, 3, 2].min(3) # => [0, 1, 2]
[1, 0, 3, 2].min(3.0) # => [0, 1, 2]
[1, 0, 3, 2].min(9) # => [0, 1, 2, 3]
[1, 0, 3, 2].min(0) # => []
With a block given, the block must return a numeric.
With a block and no argument, calls the block self.size - 1
times to compare elements; returns the element having the minimum value per the block:
['0', '', '000', '00'].min {|a, b| a.size <=> b.size }
# => ""
With non-negative numeric argument n
and a block, returns a new array with at most n
elements, in ascending order, per the block:
['0', '', '000', '00'].min(2) {|a, b| a.size <=> b.size }
# => ["", "0"]
Related: see Methods for Fetching
.
# File 'array.c', line 6111
static VALUE rb_ary_min(int argc, VALUE *argv, VALUE ary) { VALUE result = Qundef, v; VALUE num; long i; if (rb_check_arity(argc, 0, 1) && !NIL_P(num = argv[0])) return rb_nmin_run(ary, num, 0, 0, 1); const long n = RARRAY_LEN(ary); if (rb_block_given_p()) { for (i = 0; i < RARRAY_LEN(ary); i++) { v = RARRAY_AREF(ary, i); if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) < 0) { result = v; } } } else if (n > 0) { result = RARRAY_AREF(ary, 0); if (n > 1) { if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) { return ary_min_opt_fixnum(ary, 1, result); } else if (STRING_P(result) && CMP_OPTIMIZABLE(STRING)) { return ary_min_opt_string(ary, 1, result); } else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(FLOAT)) { return ary_min_opt_float(ary, 1, result); } else { return ary_min_generic(ary, 1, result); } } } if (UNDEF_P(result)) return Qnil; return result; }
#minmax ⇒ Array
#minmax {|a, b| ... } ⇒ Array
Array
#minmax {|a, b| ... } ⇒ Array
Returns a 2-element array containing the minimum-valued and maximum-valued elements from self
; does not modify self
.
With no block given, the minimum and maximum values are determined using method #<=>:
[1, 0, 3, 2].minmax # => [0, 3]
With a block given, the block must return a numeric; the block is called self.size - 1
times to compare elements; returns the elements having the minimum and maximum values per the block:
['0', '', '000', '00'].minmax {|a, b| a.size <=> b.size }
# => ["", "000"]
Related: see Methods for Fetching
.
# File 'array.c', line 6173
static VALUE rb_ary_minmax(VALUE ary) { if (rb_block_given_p()) { return rb_call_super(0, NULL); } return rb_assoc_new(rb_ary_min(0, 0, ary), rb_ary_max(0, 0, ary)); }
#none? ⇒ Boolean
#none?(object) ⇒ Boolean
#none? {|element| ... } ⇒ Boolean
Boolean
#none?(object) ⇒ Boolean
#none? {|element| ... } ⇒ Boolean
Returns true
if no element of self
meets a given criterion, false
otherwise.
With no block given and no argument, returns true
if self
has no truthy elements, false
otherwise:
[nil, false].none? # => true
[nil, 0, false].none? # => false
[].none? # => true
With argument object
given, returns false
if for any element element
, object === element
; true
otherwise:
['food', 'drink'].none?(/bar/) # => true
['food', 'drink'].none?(/foo/) # => false
[].none?(/foo/) # => true
[0, 1, 2].none?(3) # => true
[0, 1, 2].none?(1) # => false
With a block given, calls the block with each element in self
; returns true
if the block returns no truthy value, false
otherwise:
[0, 1, 2].none? {|element| element > 3 } # => true
[0, 1, 2].none? {|element| element > 1 } # => false
Related: see Methods for Querying
.
# File 'array.c', line 7818
static VALUE rb_ary_none_p(int argc, VALUE *argv, VALUE ary) { long i, len = RARRAY_LEN(ary); rb_check_arity(argc, 0, 1); if (!len) return Qtrue; if (argc) { if (rb_block_given_p()) { rb_warn("given block not used"); } for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) return Qfalse; } } else if (!rb_block_given_p()) { for (i = 0; i < len; ++i) { if (RTEST(RARRAY_AREF(ary, i))) return Qfalse; } } else { for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qfalse; } } return Qtrue; }
#one? ⇒ Boolean
#one? {|element| ... } ⇒ Boolean
#one?(object) ⇒ Boolean
Boolean
#one? {|element| ... } ⇒ Boolean
#one?(object) ⇒ Boolean
Returns true
if exactly one element of self
meets a given criterion.
With no block given and no argument, returns true
if self
has exactly one truthy element, false
otherwise:
[nil, 0].one? # => true
[0, 0].one? # => false
[nil, nil].one? # => false
[].one? # => false
With a block given, calls the block with each element in self
; returns true
if the block a truthy value for exactly one element, false
otherwise:
[0, 1, 2].one? {|element| element > 0 } # => false
[0, 1, 2].one? {|element| element > 1 } # => true
[0, 1, 2].one? {|element| element > 2 } # => false
With argument object
given, returns true
if for exactly one element element
, object === element
; false
otherwise:
[0, 1, 2].one?(0) # => true
[0, 0, 1].one?(0) # => false
[1, 1, 2].one?(0) # => false
['food', 'drink'].one?(/bar/) # => false
['food', 'drink'].one?(/foo/) # => true
[].one?(/foo/) # => false
Related: see Methods for Querying
.
# File 'array.c', line 7882
static VALUE rb_ary_one_p(int argc, VALUE *argv, VALUE ary) { long i, len = RARRAY_LEN(ary); VALUE result = Qfalse; rb_check_arity(argc, 0, 1); if (!len) return Qfalse; if (argc) { if (rb_block_given_p()) { rb_warn("given block not used"); } for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) { if (result) return Qfalse; result = Qtrue; } } } else if (!rb_block_given_p()) { for (i = 0; i < len; ++i) { if (RTEST(RARRAY_AREF(ary, i))) { if (result) return Qfalse; result = Qtrue; } } } else { for (i = 0; i < RARRAY_LEN(ary); ++i) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) { if (result) return Qfalse; result = Qtrue; } } } return result; }
#pack(template, buffer: nil) ⇒ String
Formats each element in self
into a binary string; returns that string. See Packed Data
.
# File 'pack.rb', line 7
def pack(fmt, buffer: nil) Primitive.pack_pack(fmt, buffer) end
#permutation(n = self.size) {|permutation| ... } ⇒ self
#permutation(n = self.size) ⇒ Enumerator
self
#permutation(n = self.size) ⇒ Enumerator
Iterates over permutations of the elements of self
; the order of permutations is indeterminate.
With a block and an in-range positive integer argument n
(0 < n <= self.size
) given, calls the block with each n
-tuple permutations of self
; returns self
:
a = [0, 1, 2]
perms = []
a.permutation(1) {|perm| perms.push(perm) }
perms # => [[0], [1], [2]]
perms = []
a.permutation(2) {|perm| perms.push(perm) }
perms # => [[0, 1], [0, 2], [1, 0], [1, 2], [2, 0], [2, 1]]
perms = []
a.permutation(3) {|perm| perms.push(perm) }
perms # => [[0, 1, 2], [0, 2, 1], [1, 0, 2], [1, 2, 0], [2, 0, 1], [2, 1, 0]]
When n
is zero, calls the block once with a new empty array:
perms = []
a.permutation(0) {|perm| perms.push(perm) }
perms # => [[]]
When n
is out of range (negative or larger than self.size
), does not call the block:
a.permutation(-1) {|permutation| fail 'Cannot happen' }
a.permutation(4) {|permutation| fail 'Cannot happen' }
With no block given, returns a new ::Enumerator
.
Related: Methods for Iterating
.
# File 'array.c', line 7013
static VALUE rb_ary_permutation(int argc, VALUE *argv, VALUE ary) { long r, n, i; n = RARRAY_LEN(ary); /* Array length */ RETURN_SIZED_ENUMERATOR(ary, argc, argv, rb_ary_permutation_size); /* Return enumerator if no block */ r = n; if (rb_check_arity(argc, 0, 1) && !NIL_P(argv[0])) r = NUM2LONG(argv[0]); /* Permutation size from argument */ if (r < 0 || n < r) { /* no permutations: yield nothing */ } else if (r == 0) { /* exactly one permutation: the zero-length array */ rb_yield(rb_ary_new2(0)); } else if (r == 1) { /* this is a special, easy case */ for (i = 0; i < RARRAY_LEN(ary); i++) { rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i))); } } else { /* this is the general case */ volatile VALUE t0; long *p = ALLOCV_N(long, t0, r+roomof(n, sizeof(long))); char *used = (char*)(p + r); VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ RBASIC_CLEAR_CLASS(ary0); MEMZERO(used, char, n); /* initialize array */ permute0(n, r, p, used, ary0); /* compute and yield permutations */ ALLOCV_END(t0); RBASIC_SET_CLASS_RAW(ary0, rb_cArray); } return ary; }
#pop ⇒ Object?
#pop(count) ⇒ Array
Array
Removes and returns trailing elements of self
.
With no argument given, removes and returns the last element, if available; otherwise returns nil
:
a = [:foo, 'bar', 2]
a.pop # => 2
a # => [:foo, "bar"]
[].pop # => nil
With non-negative integer argument #count given, returns a new array containing the trailing #count elements of self
, as available:
a = [:foo, 'bar', 2]
a.pop(2) # => ["bar", 2]
a # => [:foo]
a = [:foo, 'bar', 2]
a.pop(50) # => [:foo, "bar", 2]
a # => []
Related: Array#push;
see also Methods for Deleting
.
# File 'array.c', line 1479
static VALUE rb_ary_pop_m(int argc, VALUE *argv, VALUE ary) { VALUE result; if (argc == 0) { return rb_ary_pop(ary); } rb_ary_modify_check(ary); result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST); ARY_INCREASE_LEN(ary, -RARRAY_LEN(result)); ary_verify(ary); return result; }
#unshift(*objects) ⇒ self
#prepend(*objects) ⇒ self
Also known as: #unshift
self
#prepend(*objects) ⇒ self
Prepends the given objects
to self
:
a = [:foo, 'bar', 2]
a.unshift(:bam, :bat) # => [:bam, :bat, :foo, "bar", 2]
Related: Array#shift;
see also Methods for Assigning
.
# File 'array.c', line 1701
VALUE rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary) { long len = RARRAY_LEN(ary); VALUE target_ary; if (argc == 0) { rb_ary_modify_check(ary); return ary; } target_ary = ary_ensure_room_for_unshift(ary, argc); ary_memcpy0(ary, 0, argc, argv, target_ary); ARY_SET_LEN(ary, len + argc); return ary; }
#product(*other_arrays) ⇒ Array
#product(*other_arrays) {|combination| ... } ⇒ self
Array
#product(*other_arrays) {|combination| ... } ⇒ self
Computes all combinations of elements from all the arrays, including both self
and other_arrays
:
-
The number of combinations is the product of the sizes of all the arrays, including both
self
andother_arrays
. -
The order of the returned combinations is indeterminate.
With no block given, returns the combinations as an array of arrays:
p = [0, 1].product([2, 3])
# => [[0, 2], [0, 3], [1, 2], [1, 3]]
p.size # => 4
p = [0, 1].product([2, 3], [4, 5])
# => [[0, 2, 4], [0, 2, 5], [0, 3, 4], [0, 3, 5], [1, 2, 4], [1, 2, 5], [1, 3, 4], [1, 3,...
p.size # => 8
If self
or any argument is empty, returns an empty array:
[].product([2, 3], [4, 5]) # => []
[0, 1].product([2, 3], []) # => []
If no argument is given, returns an array of 1-element arrays, each containing an element of self
:
a.product # => [[0], [1], [2]]
With a block given, calls the block with each combination; returns self
:
p = []
[0, 1].product([2, 3]) {|combination| p.push(combination) }
p # => [[0, 2], [0, 3], [1, 2], [1, 3]]
If self
or any argument is empty, does not call the block:
[].product([2, 3], [4, 5]) {|combination| fail 'Cannot happen' }
# => []
[0, 1].product([2, 3], []) {|combination| fail 'Cannot happen' }
# => [0, 1]
If no argument is given, calls the block with each element of self
as a 1-element array:
p = []
[0, 1].product {|combination| p.push(combination) }
p # => [[0], [1]]
Related: see Methods for Combining
.
# File 'array.c', line 7439
static VALUE rb_ary_product(int argc, VALUE *argv, VALUE ary) { int n = argc+1; /* How many arrays we're operating on */ volatile VALUE t0 = rb_ary_hidden_new(n); volatile VALUE t1 = Qundef; VALUE *arrays = RARRAY_PTR(t0); /* The arrays we're computing the product of */ int *counters = ALLOCV_N(int, t1, n); /* The current position in each one */ VALUE result = Qnil; /* The array we'll be returning, when no block given */ long i,j; long resultlen = 1; RBASIC_CLEAR_CLASS(t0); /* initialize the arrays of arrays */ ARY_SET_LEN(t0, n); arrays[0] = ary; for (i = 1; i < n; i++) arrays[i] = Qnil; for (i = 1; i < n; i++) arrays[i] = to_ary(argv[i-1]); /* initialize the counters for the arrays */ for (i = 0; i < n; i++) counters[i] = 0; /* Otherwise, allocate and fill in an array of results */ if (rb_block_given_p()) { /* Make defensive copies of arrays; exit if any is empty */ for (i = 0; i < n; i++) { if (RARRAY_LEN(arrays[i]) == 0) goto done; arrays[i] = ary_make_shared_copy(arrays[i]); } } else { /* Compute the length of the result array; return [] if any is empty */ for (i = 0; i < n; i++) { long k = RARRAY_LEN(arrays[i]); if (k == 0) { result = rb_ary_new2(0); goto done; } if (MUL_OVERFLOW_LONG_P(resultlen, k)) rb_raise(rb_eRangeError, "too big to product"); resultlen *= k; } result = rb_ary_new2(resultlen); } for (;;) { int m; /* fill in one subarray */ VALUE subarray = rb_ary_new2(n); for (j = 0; j < n; j++) { rb_ary_push(subarray, rb_ary_entry(arrays[j], counters[j])); } /* put it on the result array */ if (NIL_P(result)) { FL_SET(t0, RARRAY_SHARED_ROOT_FLAG); rb_yield(subarray); if (!FL_TEST(t0, RARRAY_SHARED_ROOT_FLAG)) { rb_raise(rb_eRuntimeError, "product reentered"); } else { FL_UNSET(t0, RARRAY_SHARED_ROOT_FLAG); } } else { rb_ary_push(result, subarray); } /* * Increment the last counter. If it overflows, reset to 0 * and increment the one before it. */ m = n-1; counters[m]++; while (counters[m] == RARRAY_LEN(arrays[m])) { counters[m] = 0; /* If the first counter overflows, we are done */ if (--m < 0) goto done; counters[m]++; } } done: ALLOCV_END(t1); return NIL_P(result) ? ary : result; }
#push(*objects) ⇒ self
#append(*objects) ⇒ self
Also known as: #append
self
#append(*objects) ⇒ self
Appends each argument in objects
to self
; returns self
:
a = [:foo, 'bar', 2] # => [:foo, "bar", 2]
a.push(:baz, :bat) # => [:foo, "bar", 2, :baz, :bat]
Appends each argument as a single element, even if it is another array:
a = [:foo, 'bar', 2] # => [:foo, "bar", 2]
a.push([:baz, :bat], [:bam, :bad]) # => [:foo, "bar", 2, [:baz, :bat], [:bam, :bad]]
Related: see Methods for Assigning
.
# File 'array.c', line 1424
static VALUE rb_ary_push_m(int argc, VALUE *argv, VALUE ary) { return rb_ary_cat(ary, argv, argc); }
#rassoc(object) ⇒ Array
?
Returns the first element ele
in self
such that ele
is an array and ele[1] == object
:
a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
a.rassoc(4) # => [2, 4]
a.rassoc(5) # => [4, 5, 6]
Returns nil
if no such element is found.
Related: Array#assoc;
see also Methods for Fetching
.
# File 'array.c', line 5096
VALUE rb_ary_rassoc(VALUE ary, VALUE value) { long i; VALUE v; for (i = 0; i < RARRAY_LEN(ary); ++i) { v = rb_check_array_type(RARRAY_AREF(ary, i)); if (RB_TYPE_P(v, T_ARRAY) && RARRAY_LEN(v) > 1 && rb_equal(RARRAY_AREF(v, 1), value)) return v; } return Qnil; }
#reject {|element| ... } ⇒ Array
#reject ⇒ Enumerator
Array
#reject ⇒ Enumerator
With a block given, returns a new array whose elements are all those from self
for which the block returns false
or nil
:
a = [:foo, 'bar', 2, 'bat']
a1 = a.reject {|element| element.to_s.start_with?('b') }
a1 # => [:foo, 2]
With no block given, returns a new ::Enumerator
.
Related: Methods for Fetching
.
# File 'array.c', line 4343
static VALUE rb_ary_reject(VALUE ary) { VALUE rejected_ary; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rejected_ary = rb_ary_new(); ary_reject(ary, rejected_ary); return rejected_ary; }
#reject! {|element| ... } ⇒ self
?
#reject! ⇒ Enumerator
self
?
#reject! ⇒ Enumerator
With a block given, calls the block with each element of self
; removes each element for which the block returns a truthy value.
Returns self
if any elements removed:
a = [:foo, 'bar', 2, 'bat']
a.reject! {|element| element.to_s.start_with?('b') } # => [:foo, 2]
Returns nil
if no elements removed.
With no block given, returns a new ::Enumerator
.
Related: see Methods for Deleting
.
# File 'array.c', line 4318
static VALUE rb_ary_reject_bang(VALUE ary) { RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rb_ary_modify(ary); return ary_reject_bang(ary); }
#repeated_combination(size) {|combination| ... } ⇒ self
#repeated_combination(size) ⇒ Enumerator
self
#repeated_combination(size) ⇒ Enumerator
With a block given, calls the block with each repeated combination of length #size of the elements of self
; each combination is an array; returns self
. The order of the combinations is indeterminate.
If a positive integer argument #size is given, calls the block with each #size-tuple repeated combination of the elements of self
. The number of combinations is (size+1)(size+2)/2
.
Examples:
-
#size is 1:
c = [] [0, 1, 2].repeated_combination(1) {|combination| c.push(combination) } c # => [[0], [1], [2]]
-
#size is 2:
c = [] [0, 1, 2].repeated_combination(2) {|combination| c.push(combination) } c # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
If #size is zero, calls the block once with an empty array.
If #size is negative, does not call the block:
[0, 1, 2].repeated_combination(-1) {|combination| fail 'Cannot happen' }
With no block given, returns a new ::Enumerator
.
Related: see Methods for Combining
.
# File 'array.c', line 7351
static VALUE rb_ary_repeated_combination(VALUE ary, VALUE num) { long n, i, len; n = NUM2LONG(num); /* Combination size from argument */ RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_combination_size); /* Return enumerator if no block */ len = RARRAY_LEN(ary); if (n < 0) { /* yield nothing */ } else if (n == 0) { rb_yield(rb_ary_new2(0)); } else if (n == 1) { for (i = 0; i < RARRAY_LEN(ary); i++) { rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i))); } } else if (len == 0) { /* yield nothing */ } else { volatile VALUE t0; long *p = ALLOCV_N(long, t0, n); VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ RBASIC_CLEAR_CLASS(ary0); rcombinate0(len, n, p, n, ary0); /* compute and yield repeated combinations */ ALLOCV_END(t0); RBASIC_SET_CLASS_RAW(ary0, rb_cArray); } return ary; }
#repeated_permutation(size) {|permutation| ... } ⇒ self
#repeated_permutation(size) ⇒ Enumerator
self
#repeated_permutation(size) ⇒ Enumerator
With a block given, calls the block with each repeated permutation of length #size of the elements of self
; each permutation is an array; returns self
. The order of the permutations is indeterminate.
If a positive integer argument #size is given, calls the block with each #size-tuple repeated permutation of the elements of self
. The number of permutations is self.size**size
.
Examples:
-
#size is 1:
p = [] [0, 1, 2].repeated_permutation(1) {|permutation| p.push(permutation) } p # => [[0], [1], [2]]
-
#size is 2:
p = [] [0, 1, 2].repeated_permutation(2) {|permutation| p.push(permutation) } p # => [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]
If #size is zero, calls the block once with an empty array.
If #size is negative, does not call the block:
[0, 1, 2].repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
With no block given, returns a new ::Enumerator
.
Related: see Methods for Combining
.
# File 'array.c', line 7245
static VALUE rb_ary_repeated_permutation(VALUE ary, VALUE num) { long r, n, i; n = RARRAY_LEN(ary); /* Array length */ RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_permutation_size); /* Return Enumerator if no block */ r = NUM2LONG(num); /* Permutation size from argument */ if (r < 0) { /* no permutations: yield nothing */ } else if (r == 0) { /* exactly one permutation: the zero-length array */ rb_yield(rb_ary_new2(0)); } else if (r == 1) { /* this is a special, easy case */ for (i = 0; i < RARRAY_LEN(ary); i++) { rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i))); } } else { /* this is the general case */ volatile VALUE t0; long *p = ALLOCV_N(long, t0, r); VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ RBASIC_CLEAR_CLASS(ary0); rpermute0(n, r, p, ary0); /* compute and yield repeated permutations */ ALLOCV_END(t0); RBASIC_SET_CLASS_RAW(ary0, rb_cArray); } return ary; }
#initialize_copy(other_array) ⇒ self
#replace(other_array) ⇒ self
Also known as: #initialize_copy
self
#replace(other_array) ⇒ self
Replaces the elements of self
with the elements of other_array
, which must be an array-convertible object
; returns self
:
a = ['a', 'b', 'c'] # => ["a", "b", "c"]
a.replace(['d', 'e']) # => ["d", "e"]
Related: see Methods for Assigning
.
# File 'array.c', line 4586
VALUE rb_ary_replace(VALUE copy, VALUE orig) { rb_ary_modify_check(copy); orig = to_ary(orig); if (copy == orig) return copy; rb_ary_reset(copy); /* orig has enough space to embed the contents of orig. */ if (RARRAY_LEN(orig) <= ary_embed_capa(copy)) { RUBY_ASSERT(ARY_EMBED_P(copy)); ary_memcpy(copy, 0, RARRAY_LEN(orig), RARRAY_CONST_PTR(orig)); ARY_SET_EMBED_LEN(copy, RARRAY_LEN(orig)); } /* orig is embedded but copy does not have enough space to embed the * contents of orig. */ else if (ARY_EMBED_P(orig)) { long len = ARY_EMBED_LEN(orig); VALUE *ptr = ary_heap_alloc_buffer(len); FL_UNSET_EMBED(copy); ARY_SET_PTR(copy, ptr); ARY_SET_LEN(copy, len); ARY_SET_CAPA(copy, len); // No allocation and exception expected that could leave `copy` in a // bad state from the edits above. ary_memcpy(copy, 0, len, RARRAY_CONST_PTR(orig)); } /* Otherwise, orig is on heap and copy does not have enough space to embed * the contents of orig. */ else { VALUE shared_root = ary_make_shared(orig); FL_UNSET_EMBED(copy); ARY_SET_PTR(copy, ARY_HEAP_PTR(orig)); ARY_SET_LEN(copy, ARY_HEAP_LEN(orig)); rb_ary_set_shared(copy, shared_root); } ary_verify(copy); return copy; }
#reverse ⇒ Array
Returns a new array containing the elements of self
in reverse order:
[0, 1, 2].reverse # => [2, 1, 0]
Related: see Methods for Combining
.
# File 'array.c', line 3165
static VALUE rb_ary_reverse_m(VALUE ary) { long len = RARRAY_LEN(ary); VALUE dup = rb_ary_new2(len); if (len > 0) { const VALUE *p1 = RARRAY_CONST_PTR(ary); VALUE *p2 = (VALUE *)RARRAY_CONST_PTR(dup) + len - 1; do *p2-- = *p1++; while (--len > 0); } ARY_SET_LEN(dup, RARRAY_LEN(ary)); return dup; }
#reverse! ⇒ self
Reverses the order of the elements of self
; returns self
:
a = [0, 1, 2]
a.reverse! # => [2, 1, 0]
a # => [2, 1, 0]
Related: see Methods for Assigning
.
# File 'array.c', line 3148
static VALUE rb_ary_reverse_bang(VALUE ary) { return rb_ary_reverse(ary); }
#reverse_each {|element| ... } ⇒ self
#reverse_each ⇒ Enumerator
self
#reverse_each ⇒ Enumerator
When a block given, iterates backwards over the elements of self
, passing, in reverse order, each element to the block; returns self
:
a = []
[0, 1, 2].reverse_each {|element| a.push(element) }
a # => [2, 1, 0]
Allows the array to be modified during iteration:
a = ['a', 'b', 'c']
a.reverse_each {|element| a.clear if element.start_with?('b') }
a # => []
When no block given, returns a new ::Enumerator
.
Related: see Methods for Iterating
.
# File 'array.c', line 2722
static VALUE rb_ary_reverse_each(VALUE ary) { long len; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); len = RARRAY_LEN(ary); while (len--) { long nlen; rb_yield(RARRAY_AREF(ary, len)); nlen = RARRAY_LEN(ary); if (nlen < len) { len = nlen; } } return ary; }
Returns the index of the last element for which object == element
.
With argument object
given, returns the index of the last such element found:
a = [:foo, 'bar', 2, 'bar']
a.rindex('bar') # => 3
Returns nil
if no such object found.
With a block given, calls the block with each successive element; returns the index of the last element for which the block returns a truthy value:
a = [:foo, 'bar', 2, 'bar']
a.rindex {|element| element == 'bar' } # => 3
Returns nil
if the block never returns a truthy value.
When neither an argument nor a block is given, returns a new ::Enumerator
.
Related: see Methods for Querying
.
# File 'array.c', line 2163
static VALUE rb_ary_rindex(int argc, VALUE *argv, VALUE ary) { VALUE val; long i = RARRAY_LEN(ary), len; if (argc == 0) { RETURN_ENUMERATOR(ary, 0, 0); while (i--) { if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return LONG2NUM(i); if (i > (len = RARRAY_LEN(ary))) { i = len; } } return Qnil; } rb_check_arity(argc, 0, 1); val = argv[0]; if (rb_block_given_p()) rb_warn("given block not used"); while (i--) { VALUE e = RARRAY_AREF(ary, i); if (rb_equal(e, val)) { return LONG2NUM(i); } if (i > RARRAY_LEN(ary)) { break; } } return Qnil; }
#rotate(count = 1) ⇒ Array
Returns a new array formed from self
with elements rotated from one end to the other.
With non-negative numeric #count, rotates elements from the beginning to the end:
[0, 1, 2, 3].rotate(2) # => [2, 3, 0, 1]
[0, 1, 2, 3].rotate(2.1) # => [2, 3, 0, 1]
If #count is large, uses count % array.size
as the count:
[0, 1, 2, 3].rotate(22) # => [2, 3, 0, 1]
With a #count of zero, rotates no elements:
[0, 1, 2, 3].rotate(0) # => [0, 1, 2, 3]
With negative numeric #count, rotates in the opposite direction, from the end to the beginning:
[0, 1, 2, 3].rotate(-1) # => [3, 0, 1, 2]
If #count is small (far from zero), uses count % array.size
as the count:
[0, 1, 2, 3].rotate(-21) # => [3, 0, 1, 2]
Related: see Methods for Fetching
.
# File 'array.c', line 3295
static VALUE rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary) { VALUE rotated; const VALUE *ptr; long len; long cnt = (rb_check_arity(argc, 0, 1) ? NUM2LONG(argv[0]) : 1); len = RARRAY_LEN(ary); rotated = rb_ary_new2(len); if (len > 0) { cnt = rotate_count(cnt, len); ptr = RARRAY_CONST_PTR(ary); len -= cnt; ary_memcpy(rotated, 0, len, ptr + cnt); ary_memcpy(rotated, len, cnt, ptr); } ARY_SET_LEN(rotated, RARRAY_LEN(ary)); return rotated; }
#rotate!(count = 1) ⇒ self
Rotates self
in place by moving elements from one end to the other; returns self
.
With non-negative numeric #count, rotates #count elements from the beginning to the end:
[0, 1, 2, 3].rotate!(2) # => [2, 3, 0, 1]
[0, 1, 2, 3].rotate!(2.1) # => [2, 3, 0, 1]
If #count is large, uses count % array.size
as the count:
[0, 1, 2, 3].rotate!(21) # => [1, 2, 3, 0]
If #count is zero, rotates no elements:
[0, 1, 2, 3].rotate!(0) # => [0, 1, 2, 3]
With a negative numeric #count, rotates in the opposite direction, from end to beginning:
[0, 1, 2, 3].rotate!(-1) # => [3, 0, 1, 2]
If #count is small (far from zero), uses count % array.size
as the count:
[0, 1, 2, 3].rotate!(-21) # => [3, 0, 1, 2]
Related: see Methods for Assigning
.
# File 'array.c', line 3254
static VALUE rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary) { long n = (rb_check_arity(argc, 0, 1) ? NUM2LONG(argv[0]) : 1); rb_ary_rotate(ary, n); return ary; }
#sample(random: Random) ⇒ Object
#sample(count, random: Random) ⇒ Array
Array
Returns random elements from self
, as selected by the object given by keyword argument random
.
With no argument #count given, returns one random element from self
:
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a.sample # => 3
a.sample # => 8
Returns nil
if self
is empty:
[].sample # => nil
With non-negative numeric argument #count given, returns a new array containing #count random elements from self
:
a.sample(3) # => [8, 9, 2]
a.sample(6) # => [9, 6, 0, 3, 1, 4]
The order of the result array is unrelated to the order of self
.
Returns a new empty Array
if self
is empty:
[].sample(4) # => []
May return duplicates in self
:
a = [1, 1, 1, 2, 2, 3]
a.sample(a.size) # => [1, 1, 3, 2, 1, 2]
Returns no more than a.size
elements (because no new duplicates are introduced):
a.sample(50) # => [6, 4, 1, 8, 5, 9, 0, 2, 3, 7]
The object given with keyword argument random
is used as the random number generator:
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a.sample(random: Random.new(1)) #=> 6
a.sample(4, random: Random.new(1)) #=> [6, 10, 9, 2]
Related: see Methods for Fetching
.
# File 'array.rb', line 96
def sample(n = (ary = false), random: Random) if Primitive.mandatory_only? # Primitive.cexpr! %{ rb_ary_sample(self, rb_cRandom, Qfalse, Qfalse) } Primitive.ary_sample0 else # Primitive.cexpr! %{ rb_ary_sample(self, random, n, ary) } Primitive.ary_sample(random, n, ary) end end
#select {|element| ... } ⇒ Array
#select ⇒ Enumerator
#filter {|element| ... } ⇒ Array
#filter ⇒ Enumerator
Array
#select ⇒ Enumerator
#filter {|element| ... } ⇒ Array
#filter ⇒ Enumerator
Alias for #filter.
#select! {|element| ... } ⇒ self
?
#select! ⇒ Enumerator
#filter! {|element| ... } ⇒ self
?
#filter! ⇒ Enumerator
self
?
#select! ⇒ Enumerator
#filter! {|element| ... } ⇒ self
?
#filter! ⇒ Enumerator
Alias for #filter!.
#shift ⇒ Object?
#shift(count) ⇒ Array
?
Array
?
Removes and returns leading elements from self
.
With no argument, removes and returns one element, if available, or nil
otherwise:
a = [0, 1, 2, 3]
a.shift # => 0
a # => [1, 2, 3]
[].shift # => nil
With non-negative numeric argument #count given, removes and returns the first #count elements:
a = [0, 1, 2, 3]
a.shift(2) # => [0, 1]
a # => [2, 3]
a.shift(1.1) # => [2]
a # => [3]
a.shift(0) # => []
a # => [3]
If #count is large, removes and returns all elements:
a = [0, 1, 2, 3]
a.shift(50) # => [0, 1, 2, 3]
a # => []
If self
is empty, returns a new empty array.
Related: see Methods for Deleting
.
# File 'array.c', line 1551
static VALUE rb_ary_shift_m(int argc, VALUE *argv, VALUE ary) { VALUE result; long n; if (argc == 0) { return rb_ary_shift(ary); } rb_ary_modify_check(ary); result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST); n = RARRAY_LEN(result); rb_ary_behead(ary,n); return result; }
#shuffle(random: Random) ⇒ Array
Returns a new array containing all elements from self
in a random order, as selected by the object given by keyword argument random
:
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a.shuffle # => [0, 8, 1, 9, 6, 3, 4, 7, 2, 5]
a.shuffle # => [8, 9, 0, 5, 1, 2, 6, 4, 7, 3]
Duplicate elements are included:
a = [0, 1, 0, 1, 0, 1, 0, 1, 0, 1]
a.shuffle # => [1, 0, 1, 1, 0, 0, 1, 0, 0, 1]
a.shuffle # => [1, 1, 0, 0, 0, 1, 1, 0, 0, 1]
The object given with keyword argument random
is used as the random number generator.
Related: see Methods for Fetching
.
# File 'array.rb', line 45
def shuffle(random: Random) Primitive.rb_ary_shuffle(random) end
#shuffle!(random: Random) ⇒ self
Shuffles all elements in self
into a random order, as selected by the object given by keyword argument random
; returns self
:
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a.shuffle! # => [5, 3, 8, 7, 6, 1, 9, 4, 2, 0]
a.shuffle! # => [9, 4, 0, 6, 2, 8, 1, 5, 3, 7]
Duplicate elements are included:
a = [0, 1, 0, 1, 0, 1, 0, 1, 0, 1]
a.shuffle! # => [1, 0, 0, 1, 1, 0, 1, 0, 0, 1]
a.shuffle! # => [0, 1, 0, 1, 1, 0, 1, 0, 1, 0]
The object given with keyword argument random
is used as the random number generator.
Related: see Methods for Assigning
.
# File 'array.rb', line 22
def shuffle!(random: Random) Primitive.rb_ary_shuffle_bang(random) end
Alias for #length.
Alias for #[].
Removes and returns elements from self
.
With numeric argument #index given, removes and returns the element at offset #index:
a = ['a', 'b', 'c', 'd']
a.slice!(2) # => "c"
a # => ["a", "b", "d"]
a.slice!(2.1) # => "d"
a # => ["a", "b"]
If #index is negative, counts backwards from the end of self
:
a = ['a', 'b', 'c', 'd']
a.slice!(-2) # => "c"
a # => ["a", "b", "d"]
If #index is out of range, returns nil
.
With numeric arguments start
and #length given, removes #length elements from self
beginning at zero-based offset start
; returns the removed objects in a new array:
a = ['a', 'b', 'c', 'd']
a.slice!(1, 2) # => ["b", "c"]
a # => ["a", "d"]
a.slice!(0.1, 1.1) # => ["a"]
a # => ["d"]
If start
is negative, counts backwards from the end of self
:
a = ['a', 'b', 'c', 'd']
a.slice!(-2, 1) # => ["c"]
a # => ["a", "b", "d"]
If start
is out-of-range, returns nil
:
a = ['a', 'b', 'c', 'd']
a.slice!(5, 1) # => nil
a.slice!(-5, 1) # => nil
If start + length
exceeds the array size, removes and returns all elements from offset start
to the end:
a = ['a', 'b', 'c', 'd']
a.slice!(2, 50) # => ["c", "d"]
a # => ["a", "b"]
If start == a.size
and #length is non-negative, returns a new empty array.
If #length is negative, returns nil
.
With Range argument range
given, treats range.min
as start
(as above) and range.size
as #length (as above):
a = ['a', 'b', 'c', 'd']
a.slice!(1..2) # => ["b", "c"]
a # => ["a", "d"]
If range.start == a.size
, returns a new empty array:
a = ['a', 'b', 'c', 'd']
a.slice!(4..5) # => []
If range.start
is larger than the array size, returns nil
:
a = ['a', 'b', 'c', 'd']
a.slice!(5..6) # => nil
If range.start
is negative, calculates the start index by counting backwards from the end of self
:
a = ['a', 'b', 'c', 'd']
a.slice!(-2..2) # => ["c"]
If range.end
is negative, calculates the end index by counting backwards from the end of self
:
a = ['a', 'b', 'c', 'd']
a.slice!(0..-2) # => ["a", "b", "c"]
Related: see Methods for Deleting
.
# File 'array.c', line 4222
static VALUE rb_ary_slice_bang(int argc, VALUE *argv, VALUE ary) { VALUE arg1; long pos, len; rb_ary_modify_check(ary); rb_check_arity(argc, 1, 2); arg1 = argv[0]; if (argc == 2) { pos = NUM2LONG(argv[0]); len = NUM2LONG(argv[1]); return ary_slice_bang_by_rb_ary_splice(ary, pos, len); } if (!FIXNUM_P(arg1)) { switch (rb_range_beg_len(arg1, &pos, &len, RARRAY_LEN(ary), 0)) { case Qtrue: /* valid range */ return ary_slice_bang_by_rb_ary_splice(ary, pos, len); case Qnil: /* invalid range */ return Qnil; default: /* not a range */ break; } } return rb_ary_delete_at(ary, NUM2LONG(arg1)); }
#sort ⇒ Array
#sort {|a, b| ... } ⇒ Array
Array
#sort {|a, b| ... } ⇒ Array
Returns a new array containing the elements of self
, sorted.
With no block given, compares elements using operator #<=> (see Object#<=>):
[0, 2, 3, 1].sort # => [0, 1, 2, 3]
With a block given, calls the block with each combination of pairs of elements from self
; for each pair a
and b
, the block should return a numeric:
-
Negative when
b
is to followa
. -
Zero when
a
andb
are equivalent. -
Positive when
a
is to followb
.
Example:
a = [3, 2, 0, 1]
a.sort {|a, b| a <=> b } # => [0, 1, 2, 3]
a.sort {|a, b| b <=> a } # => [3, 2, 1, 0]
When the block returns zero, the order for a
and b
is indeterminate, and may be unstable.
Related: see Methods for Fetching
.
# File 'array.c', line 3486
VALUE rb_ary_sort(VALUE ary) { ary = rb_ary_dup(ary); rb_ary_sort_bang(ary); return ary; }
#sort! ⇒ self
#sort! {|a, b| ... } ⇒ self
self
#sort! {|a, b| ... } ⇒ self
Like #sort, but returns self
with its elements sorted in place.
Related: see Methods for Assigning
.
# File 'array.c', line 3393
VALUE rb_ary_sort_bang(VALUE ary) { rb_ary_modify(ary); RUBY_ASSERT(!ARY_SHARED_P(ary)); if (RARRAY_LEN(ary) > 1) { VALUE tmp = ary_make_substitution(ary); /* only ary refers tmp */ struct ary_sort_data data; long len = RARRAY_LEN(ary); RBASIC_CLEAR_CLASS(tmp); data.ary = tmp; data.receiver = ary; RARRAY_PTR_USE(tmp, ptr, { ruby_qsort(ptr, len, sizeof(VALUE), rb_block_given_p()?sort_1:sort_2, &data); }); /* WB: no new reference */ rb_ary_modify(ary); if (ARY_EMBED_P(tmp)) { if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */ rb_ary_unshare(ary); FL_SET_EMBED(ary); } if (ARY_EMBED_LEN(tmp) > ARY_CAPA(ary)) { ary_resize_capa(ary, ARY_EMBED_LEN(tmp)); } ary_memcpy(ary, 0, ARY_EMBED_LEN(tmp), ARY_EMBED_PTR(tmp)); ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp)); } else { if (!ARY_EMBED_P(ary) && ARY_HEAP_PTR(ary) == ARY_HEAP_PTR(tmp)) { FL_UNSET_SHARED(ary); ARY_SET_CAPA(ary, RARRAY_LEN(tmp)); } else { RUBY_ASSERT(!ARY_SHARED_P(tmp)); if (ARY_EMBED_P(ary)) { FL_UNSET_EMBED(ary); } else if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */ rb_ary_unshare(ary); } else { ary_heap_free(ary); } ARY_SET_PTR(ary, ARY_HEAP_PTR(tmp)); ARY_SET_HEAP_LEN(ary, len); ARY_SET_CAPA(ary, ARY_HEAP_LEN(tmp)); } /* tmp was lost ownership for the ptr */ FL_UNSET(tmp, FL_FREEZE); FL_SET_EMBED(tmp); ARY_SET_EMBED_LEN(tmp, 0); FL_SET(tmp, FL_FREEZE); } /* tmp will be GC'ed. */ RBASIC_SET_CLASS_RAW(tmp, rb_cArray); /* rb_cArray must be marked */ } ary_verify(ary); return ary; }
#sort_by! {|element| ... } ⇒ self
#sort_by! ⇒ Enumerator
self
#sort_by! ⇒ Enumerator
With a block given, sorts the elements of self
in place; returns self.
Calls the block with each successive element; sorts elements based on the values returned from the block:
a = ['aaaa', 'bbb', 'cc', 'd']
a.sort_by! {|element| element.size }
a # => ["d", "cc", "bbb", "aaaa"]
For duplicate values returned by the block, the ordering is indeterminate, and may be unstable.
With no block given, returns a new ::Enumerator
.
Related: see Methods for Assigning
.
# File 'array.c', line 3609
static VALUE rb_ary_sort_by_bang(VALUE ary) { VALUE sorted; RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length); rb_ary_modify(ary); sorted = rb_block_call(ary, rb_intern("sort_by"), 0, 0, sort_by_i, 0); rb_ary_replace(ary, sorted); return ary; }
With no block given, returns the sum of init
and all elements of self
; for array array
and value init
, equivalent to:
sum = init
array.each {|element| sum += element }
sum
For example, [e0, e1, e2].sum
returns init + e0 + e1 + e2
.
Examples:
[0, 1, 2, 3].sum # => 6
[0, 1, 2, 3].sum(100) # => 106
['abc', 'def', 'ghi'].sum('jkl') # => "jklabcdefghi"
[[:foo, : ], ['foo', 'bar']].sum([2, 3])
# => [2, 3, :foo, :bar, "foo", "bar"]
The init
value and elements need not be numeric, but must all be +
-compatible:
# Raises TypeError: Array can't be coerced into Integer.
[[:foo, : ], ['foo', 'bar']].sum(2)
With a block given, calls the block with each element of self
; the block’s return value (instead of the element itself) is used as the addend:
['zero', 1, :two].sum('Coerced and concatenated: ') {|element| element.to_s }
# => "Coerced and concatenated: zero1two"
Notes:
# File 'array.c', line 8005
static VALUE rb_ary_sum(int argc, VALUE *argv, VALUE ary) { VALUE e, v, r; long i, n; int block_given; v = (rb_check_arity(argc, 0, 1) ? argv[0] : LONG2FIX(0)); block_given = rb_block_given_p(); if (RARRAY_LEN(ary) == 0) return v; n = 0; r = Qundef; if (!FIXNUM_P(v) && !RB_BIGNUM_TYPE_P(v) && !RB_TYPE_P(v, T_RATIONAL)) { i = 0; goto init_is_a_value; } for (i = 0; i < RARRAY_LEN(ary); i++) { e = RARRAY_AREF(ary, i); if (block_given) e = rb_yield(e); if (FIXNUM_P(e)) { n += FIX2LONG(e); /* should not overflow long type */ if (!FIXABLE(n)) { v = rb_big_plus(LONG2NUM(n), v); n = 0; } } else if (RB_BIGNUM_TYPE_P(e)) v = rb_big_plus(e, v); else if (RB_TYPE_P(e, T_RATIONAL)) { if (UNDEF_P(r)) r = e; else r = rb_rational_plus(r, e); } else goto not_exact; } v = finish_exact_sum(n, r, v, argc!=0); return v; not_exact: v = finish_exact_sum(n, r, v, i!=0); if (RB_FLOAT_TYPE_P(e)) { /* * Kahan-Babuska balancing compensated summation algorithm * See https://link.springer.com/article/10.1007/s00607-005-0139-x */ double f, c; double x, t; f = NUM2DBL(v); c = 0.0; goto has_float_value; for (; i < RARRAY_LEN(ary); i++) { e = RARRAY_AREF(ary, i); if (block_given) e = rb_yield(e); if (RB_FLOAT_TYPE_P(e)) has_float_value: x = RFLOAT_VALUE(e); else if (FIXNUM_P(e)) x = FIX2LONG(e); else if (RB_BIGNUM_TYPE_P(e)) x = rb_big2dbl(e); else if (RB_TYPE_P(e, T_RATIONAL)) x = rb_num2dbl(e); else goto not_float; if (isnan(f)) continue; if (isnan(x)) { f = x; continue; } if (isinf(x)) { if (isinf(f) && signbit(x) != signbit(f)) f = NAN; else f = x; continue; } if (isinf(f)) continue; t = f + x; if (fabs(f) >= fabs(x)) c += ((f - t) + x); else c += ((x - t) + f); f = t; } f += c; return DBL2NUM(f); not_float: v = DBL2NUM(f); } goto has_some_value; init_is_a_value: for (; i < RARRAY_LEN(ary); i++) { e = RARRAY_AREF(ary, i); if (block_given) e = rb_yield(e); has_some_value: v = rb_funcall(v, idPLUS, 1, e); } return v; }
#take(count) ⇒ Array
Returns a new array containing the first #count element of self
(as available); #count must be a non-negative numeric; does not modify self
:
a = ['a', 'b', 'c', 'd']
a.take(2) # => ["a", "b"]
a.take(2.1) # => ["a", "b"]
a.take(50) # => ["a", "b", "c", "d"]
a.take(0) # => []
Related: see Methods for Fetching
.
# File 'array.c', line 7545
static VALUE rb_ary_take(VALUE obj, VALUE n) { long len = NUM2LONG(n); if (len < 0) { rb_raise(rb_eArgError, "attempt to take negative size"); } return rb_ary_subseq(obj, 0, len); }
#take_while {|element| ... } ⇒ Array
#take_while ⇒ Enumerator
Array
#take_while ⇒ Enumerator
With a block given, calls the block with each successive element of self
; stops iterating if the block returns false
or nil
; returns a new array containing those elements for which the block returned a truthy value:
a = [0, 1, 2, 3, 4, 5]
a.take_while {|element| element < 3 } # => [0, 1, 2]
a.take_while {|element| true } # => [0, 1, 2, 3, 4, 5]
a.take_while {|element| false } # => []
With no block given, returns a new ::Enumerator
.
Does not modify self
.
Related: see Methods for Fetching
.
# File 'array.c', line 7576
static VALUE rb_ary_take_while(VALUE ary) { long i; RETURN_ENUMERATOR(ary, 0, 0); for (i = 0; i < RARRAY_LEN(ary); i++) { if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break; } return rb_ary_take(ary, LONG2FIX(i)); }
#to_a ⇒ self
, Array
When self
is an instance of Array
, returns self
.
Otherwise, returns a new array containing the elements of self
:
class MyArray < Array; end
my_a = MyArray.new(['foo', 'bar', 'two'])
a = my_a.to_a
a # => ["foo", "bar", "two"]
a.class # => Array # Not MyArray.
Related: see Methods for Converting
.
# File 'array.c', line 3035
static VALUE rb_ary_to_a(VALUE ary) { if (rb_obj_class(ary) != rb_cArray) { VALUE dup = rb_ary_new2(RARRAY_LEN(ary)); rb_ary_replace(dup, ary); return dup; } return ary; }
#to_ary ⇒ self
Returns self
.
# File 'array.c', line 3102
static VALUE rb_ary_to_ary_m(VALUE ary) { return ary; }
Returns a new hash formed from self
.
With no block given, each element of self
must be a 2-element sub-array; forms each sub-array into a key-value pair in the new hash:
a = [['foo', 'zero'], ['bar', 'one'], ['baz', 'two']]
a.to_h # => {"foo"=>"zero", "bar"=>"one", "baz"=>"two"}
[].to_h # => {}
With a block given, the block must return a 2-element array; calls the block with each element of self
; forms each returned array into a key-value pair in the returned hash:
a = ['foo', :, 1, [2, 3], {baz: 4}]
a.to_h {|element| [element, element.class] }
# => {"foo"=>String, :bar=>Symbol, 1=>Integer, [2, 3]=>Array, {:baz=>4}=>Hash}
Related: see Methods for Converting
.
# File 'array.c', line 3071
static VALUE rb_ary_to_h(VALUE ary) { long i; VALUE hash = rb_hash_new_with_size(RARRAY_LEN(ary)); int block_given = rb_block_given_p(); for (i=0; i<RARRAY_LEN(ary); i++) { const VALUE e = rb_ary_elt(ary, i); const VALUE elt = block_given ? rb_yield_force_blockarg(e) : e; const VALUE key_value_pair = rb_check_array_type(elt); if (NIL_P(key_value_pair)) { rb_raise(rb_eTypeError, "wrong element type %"PRIsVALUE" at %ld (expected array)", rb_obj_class(elt), i); } if (RARRAY_LEN(key_value_pair) != 2) { rb_raise(rb_eArgError, "wrong array length at %ld (expected 2, was %ld)", i, RARRAY_LEN(key_value_pair)); } rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1)); } return hash; }
Also known as: #inspect
# File 'array.c', line 3005
static VALUE rb_ary_inspect(VALUE ary) { if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new2("[]"); return rb_exec_recursive(inspect_ary, ary, 0); }
#transpose ⇒ Array
Returns a new array that is self
as a transposed matrix:
a = [[:a0, :a1], [:b0, :b1], [:c0, :c1]]
a.transpose # => [[:a0, :b0, :c0], [:a1, :b1, :c1]]
The elements of self
must all be the same size.
Related: see Methods for Converting
.
# File 'array.c', line 4543
static VALUE rb_ary_transpose(VALUE ary) { long elen = -1, alen, i, j; VALUE tmp, result = 0; alen = RARRAY_LEN(ary); if (alen == 0) return rb_ary_dup(ary); for (i=0; i<alen; i++) { tmp = to_ary(rb_ary_elt(ary, i)); if (elen < 0) { /* first element */ elen = RARRAY_LEN(tmp); result = rb_ary_new2(elen); for (j=0; j<elen; j++) { rb_ary_store(result, j, rb_ary_new2(alen)); } } else if (elen != RARRAY_LEN(tmp)) { rb_raise(rb_eIndexError, "element size differs (%ld should be %ld)", RARRAY_LEN(tmp), elen); } for (j=0; j<elen; j++) { rb_ary_store(rb_ary_elt(result, j), i, rb_ary_elt(tmp, j)); } } return result; }
#union(*other_arrays) ⇒ Array
Returns a new array that is the union of the elements of self
and all given arrays other_arrays
; items are compared using #eql?:
[0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7]
Removes duplicates (preserving the first found):
[0, 1, 1].union([2, 1], [3, 1]) # => [0, 1, 2, 3]
Preserves order (preserving the position of the first found):
[3, 2, 1, 0].union([5, 3], [4, 2]) # => [3, 2, 1, 0, 5, 4]
With no arguments given, returns a copy of self
.
Related: see Methods for Combining
.
# File 'array.c', line 5715
static VALUE rb_ary_union_multi(int argc, VALUE *argv, VALUE ary) { int i; long sum; VALUE hash; sum = RARRAY_LEN(ary); for (i = 0; i < argc; i++) { argv[i] = to_ary(argv[i]); sum += RARRAY_LEN(argv[i]); } if (sum <= SMALL_ARRAY_LEN) { VALUE ary_union = rb_ary_new(); rb_ary_union(ary_union, ary); for (i = 0; i < argc; i++) rb_ary_union(ary_union, argv[i]); return ary_union; } hash = ary_make_hash(ary); for (i = 0; i < argc; i++) rb_ary_union_hash(hash, argv[i]); return rb_hash_values(hash); }
#uniq ⇒ Array
#uniq {|element| ... } ⇒ Array
Array
#uniq {|element| ... } ⇒ Array
Returns a new array containing those elements from self
that are not duplicates, the first occurrence always being retained.
With no block given, identifies and omits duplicate elements using method #eql? to compare elements:
a = [0, 0, 1, 1, 2, 2]
a.uniq # => [0, 1, 2]
With a block given, calls the block for each element; identifies and omits “duplicate” elements using method #eql? to compare block return values; that is, an element is a duplicate if its block return value is the same as that of a previous element:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
Related: Methods for Fetching
.
# File 'array.c', line 6272
static VALUE rb_ary_uniq(VALUE ary) { VALUE hash, uniq; if (RARRAY_LEN(ary) <= 1) { hash = 0; uniq = rb_ary_dup(ary); } else if (rb_block_given_p()) { hash = ary_make_hash_by(ary); uniq = rb_hash_values(hash); } else { hash = ary_make_hash(ary); uniq = rb_hash_values(hash); } return uniq; }
#uniq! ⇒ self
?
#uniq! {|element| ... } ⇒ self
?
self
?
#uniq! {|element| ... } ⇒ self
?
Removes duplicate elements from self
, the first occurrence always being retained; returns self
if any elements removed, nil
otherwise.
With no block given, identifies and removes elements using method #eql? to compare elements:
a = [0, 0, 1, 1, 2, 2]
a.uniq! # => [0, 1, 2]
a.uniq! # => nil
With a block given, calls the block for each element; identifies and omits “duplicate” elements using method #eql? to compare block return values; that is, an element is a duplicate if its block return value is the same as that of a previous element:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
a.uniq! {|element| element.size } # => ["a", "aa", "aaa"]
a.uniq! {|element| element.size } # => nil
Related: see Methods for Deleting
.
# File 'array.c', line 6216
static VALUE rb_ary_uniq_bang(VALUE ary) { VALUE hash; long hash_size; rb_ary_modify_check(ary); if (RARRAY_LEN(ary) <= 1) return Qnil; if (rb_block_given_p()) hash = ary_make_hash_by(ary); else hash = ary_make_hash(ary); hash_size = RHASH_SIZE(hash); if (RARRAY_LEN(ary) == hash_size) { return Qnil; } rb_ary_modify_check(ary); ARY_SET_LEN(ary, 0); if (ARY_SHARED_P(ary)) { rb_ary_unshare(ary); FL_SET_EMBED(ary); } ary_resize_capa(ary, hash_size); rb_hash_foreach(hash, push_value, ary); return ary; }
#unshift(*objects) ⇒ self
#prepend(*objects) ⇒ self
self
#prepend(*objects) ⇒ self
Alias for #prepend.
#values_at(*indexes) ⇒ Array
Returns a new Array
whose elements are the elements of self
at the given ::Integer
or ::Range
indexes
.
For each positive #index, returns the element at offset #index:
a = [:foo, 'bar', 2]
a.values_at(0, 2) # => [:foo, 2]
a.values_at(0..1) # => [:foo, "bar"]
The given indexes
may be in any order, and may repeat:
a = [:foo, 'bar', 2]
a.values_at(2, 0, 1, 0, 2) # => [2, :foo, "bar", :foo, 2]
a.values_at(1, 0..2) # => ["bar", :foo, "bar", 2]
Assigns nil
for an #index that is too large:
a = [:foo, 'bar', 2]
a.values_at(0, 3, 1, 3) # => [:foo, nil, "bar", nil]
Returns a new empty Array
if no arguments given.
For each negative #index, counts backward from the end of the array:
a = [:foo, 'bar', 2]
a.values_at(-1, -3) # => [2, :foo]
Assigns nil
for an #index that is too small:
a = [:foo, 'bar', 2]
a.values_at(0, -5, 1, -6, 2) # => [:foo, nil, "bar", nil, 2]
The given indexes
may have a mixture of signs:
a = [:foo, 'bar', 2]
a.values_at(0, -2, 1, -1) # => [:foo, "bar", "bar", 2]
# File 'array.c', line 3787
static VALUE rb_ary_values_at(int argc, VALUE *argv, VALUE ary) { long i, olen = RARRAY_LEN(ary); VALUE result = rb_ary_new_capa(argc); for (i = 0; i < argc; ++i) { append_values_at_single(result, ary, olen, argv[i]); } RB_GC_GUARD(ary); return result; }
#zip(*other_arrays) ⇒ Array
#zip(*other_arrays) {|other_array| ... } ⇒ nil
Array
#zip(*other_arrays) {|other_array| ... } ⇒ nil
When no block given, returns a new Array
new_array
of size self.size
whose elements are Arrays.
Each nested array new_array[n]
is of size other_arrays.size+1
, and contains:
-
The nth element of
self
. -
The nth element of each of the
other_arrays
.
If all other_arrays
and self
are the same size:
a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3]
c = [:c0, :c1, :c2, :c3]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
If any array in other_arrays
is smaller than self
, fills to self.size
with nil
:
a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2]
c = [:c0, :c1]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, nil], [:a3, nil, nil]]
If any array in other_arrays
is larger than self
, its trailing elements are ignored:
a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3, :b4]
c = [:c0, :c1, :c2, :c3, :c4, :c5]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
If an argument is not an array, it extracts the values by calling #each:
a = [:a0, :a1, :a2, :a2]
b = 1..4
c = a.zip(b)
c # => [[:a0, 1], [:a1, 2], [:a2, 3], [:a2, 4]]
When a block is given, calls the block with each of the sub-arrays (formed as above); returns nil
:
a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3]
c = [:c0, :c1, :c2, :c3]
a.zip(b, c) {|sub_array| p sub_array} # => nil
Output:
[:a0, :b0, :c0]
[:a1, :b1, :c1]
[:a2, :b2, :c2]
[:a3, :b3, :c3]
# File 'array.c', line 4470
static VALUE rb_ary_zip(int argc, VALUE *argv, VALUE ary) { int i, j; long len = RARRAY_LEN(ary); VALUE result = Qnil; for (i=0; i<argc; i++) { argv[i] = take_items(argv[i], len); } if (rb_block_given_p()) { int arity = rb_block_arity(); if (arity > 1) { VALUE work, *tmp; tmp = ALLOCV_N(VALUE, work, argc+1); for (i=0; i<RARRAY_LEN(ary); i++) { tmp[0] = RARRAY_AREF(ary, i); for (j=0; j<argc; j++) { tmp[j+1] = rb_ary_elt(argv[j], i); } rb_yield_values2(argc+1, tmp); } if (work) ALLOCV_END(work); } else { for (i=0; i<RARRAY_LEN(ary); i++) { VALUE tmp = rb_ary_new2(argc+1); rb_ary_push(tmp, RARRAY_AREF(ary, i)); for (j=0; j<argc; j++) { rb_ary_push(tmp, rb_ary_elt(argv[j], i)); } rb_yield(tmp); } } } else { result = rb_ary_new_capa(len); for (i=0; i<len; i++) { VALUE tmp = rb_ary_new_capa(argc+1); rb_ary_push(tmp, RARRAY_AREF(ary, i)); for (j=0; j<argc; j++) { rb_ary_push(tmp, rb_ary_elt(argv[j], i)); } rb_ary_push(result, tmp); } } return result; }
#|(other_array) ⇒ Array
# File 'array.c', line 5673
static VALUE rb_ary_or(VALUE ary1, VALUE ary2) { VALUE hash; ary2 = to_ary(ary2); if (RARRAY_LEN(ary1) + RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) { VALUE ary3 = rb_ary_new(); rb_ary_union(ary3, ary1); rb_ary_union(ary3, ary2); return ary3; } hash = ary_make_hash(ary1); rb_ary_union_hash(hash, ary2); return rb_hash_values(hash); }