Class: CSV::Row
Relationships & Source Files | |
Super Chains via Extension / Inclusion / Inheritance | |
Class Chain:
self,
Forwardable
|
|
Instance Chain:
self,
Enumerable
|
|
Inherits: | Object |
Defined in: | lib/csv/row.rb |
Overview
A CSV::Row instance represents a CSV table row. (see class CSV
).
The instance may have:
-
Fields: each is an object, not necessarily a String.
-
Headers: each serves a key, and also need not be a String.
Instance Methods
CSV::Row has three groups of instance methods:
-
Its own internally defined instance methods.
-
Methods included by module Enumerable.
-
Methods delegated to class
::Array
.:-
Array#empty?
-
Array#length
-
Array#size
-
Creating a CSV::Row Instance
Commonly, a new CSV::Row instance is created by parsing CSV source that has headers:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.each {|row| p row }
Output:
#<CSV::Row "Name":"foo" "Value":"0">
#<CSV::Row "Name":"bar" "Value":"1">
#<CSV::Row "Name":"baz" "Value":"2">
You can also create a row directly. See .new.
Headers
Like a CSV::Table, a CSV::Row has headers.
A CSV::Row that was created by parsing CSV source inherits its headers from the table:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table.first
row.headers # => ["Name", "Value"]
You can also create a new row with headers; like the keys in a Hash, the headers need not be Strings:
row = CSV::Row.new([:name, :value], ['foo', 0])
row.headers # => [:name, :value]
The new row retains its headers even if added to a table that has headers:
table << row # => #<CSV::Table mode:col_or_row row_count:5>
row.headers # => [:name, :value]
row[:name] # => "foo"
row['Name'] # => nil
Accessing Fields
You may access a field in a CSV::Row with either its Integer index (Array-style) or its header (Hash-style).
Fetch a field using method #[]:
row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
row[1] # => 0
row['Value'] # => 0
Set a field using method #[]=:
row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
row # => #<CSV::Row "Name":"foo" "Value":0>
row[0] = 'bar'
row['Value'] = 1
row # => #<CSV::Row "Name":"bar" "Value":1>
Class Method Summary
- .new(headers, fields, header_row = false) ⇒ Row constructor
Instance Attribute Summary
-
#field_row? ⇒ Boolean
readonly
Returns
true
if this is a field row,false
otherwise. -
#header_row? ⇒ Boolean
readonly
Returns
true
if this is a header row,false
otherwise. -
#row
readonly
protected
Internal data format used to compare equality.
Instance Method Summary
-
#<<(hash) ⇒ self
Adds a field to
self
; returnsself
: -
#==(other) ⇒ Boolean
Returns
true
ifother
is a /CSV::Row that has the same fields (headers and values) in the same order asself
; otherwise returnsfalse
: -
#[](header_or_index, minimum_index = 0)
Alias for #field.
-
#[]=(index, value) ⇒ value
Assigns the field value for the given #index or
header
; returnsvalue
. -
#deconstruct ⇒ Array
Returns the new Array suitable for pattern matching containing the values of the row.
-
#deconstruct_keys(keys) ⇒ Hash
Returns the new Hash suitable for pattern matching containing only the keys specified as an argument.
-
#delete(index) ⇒ Array, value
Removes a specified field from
self
; returns the 2-element Array[header, value]
if the field exists. -
#delete_if {|header, value| ... } ⇒ self
Removes fields from
self
as selected by the block; returnsself
. -
#dig(index_or_header, *identifiers) ⇒ Object
Finds and returns the object in nested object that is specified by
index_or_header
andspecifiers
. -
#each {|header, value| ... } ⇒ self
(also: #each_pair)
Calls the block with each header-value pair; returns
self
: -
#each_pair(&block)
Alias for #each.
-
#fetch(header) ⇒ value
Returns the field value as specified by
header
. -
#field(index) ⇒ value
(also: #[])
Returns the field value for the given #index or
header
. -
#field?(value) ⇒ Boolean
Returns
true
ifvalue
is a field in this row,false
otherwise: -
#fields(*specifiers) ⇒ array_of_fields
(also: #values_at)
Returns field values per the given
specifiers
, which may be any mixture of: - Integer index. -
#has_key?(header) ⇒ Boolean
(also: #include?, #key?, #member?, #header?)
Returns
true
if there is a field with the givenheader
,false
otherwise. -
#header?(header)
Alias for #has_key?.
-
#headers ⇒ array_of_headers
Returns the headers for this row:
-
#include?(header)
Alias for #has_key?.
-
#index(header) ⇒ index
Returns the index for the given header, if it exists; otherwise returns
nil
. -
#initialize_copy(other_row) ⇒ self
Calls superclass method.
-
#inspect ⇒ String
Returns an ASCII-compatible String showing: - Class CSV::Row.
-
#key?(header)
Alias for #has_key?.
-
#member?(header)
Alias for #has_key?.
-
#push(*values) ⇒ self
Appends each of the given
values
toself
as a field; returnsself
: - #to_ary
-
#to_csv ⇒ csv_string
(also: #to_s)
Returns the row as a CSV
::String
. -
#to_h ⇒ Hash
(also: #to_hash)
Returns the new Hash formed by adding each header-value pair in
self
as a key-value pair in the Hash. -
#to_hash
Alias for #to_h.
-
#to_s(**options)
Alias for #to_csv.
-
#values_at(*headers_and_or_indices)
Alias for #fields.
Constructor Details
.new(headers, fields, header_row = false) ⇒ Row
Returns the new CSV::Row instance constructed from arguments #headers and #fields; both should be Arrays; note that the fields need not be Strings:
row = CSV::Row.new(['Name', 'Value'], ['foo', 0])
row # => #<CSV::Row "Name":"foo" "Value":0>
If the Array lengths are different, the shorter is nil
-filled:
row = CSV::Row.new(['Name', 'Value', 'Date', 'Size'], ['foo', 0])
row # => #<CSV::Row "Name":"foo" "Value":0 "Date":nil "Size":nil>
Each CSV::Row object is either a field row or a header row; by default, a new row is a field row; for the row created above:
row.field_row? # => true
row.header_row? # => false
If the optional argument header_row
is given as true
, the created row is a header row:
row = CSV::Row.new(['Name', 'Value'], ['foo', 0], header_row = true)
row # => #<CSV::Row "Name":"foo" "Value":0>
row.field_row? # => false
row.header_row? # => true
Instance Attribute Details
#field_row? ⇒ Boolean
(readonly)
Returns true
if this is a field row, false
otherwise.
# File 'lib/csv/row.rb', line 148
def field_row? not header_row? end
#header_row? ⇒ Boolean
(readonly)
Returns true
if this is a header row, false
otherwise.
# File 'lib/csv/row.rb', line 140
def header_row? @header_row end
#row (readonly, protected)
Internal data format used to compare equality.
# File 'lib/csv/row.rb', line 118
attr_reader :row
Instance Method Details
#row(<< [header, value]) ⇒ self
#<<(hash) ⇒ self
#<<(value) ⇒ self
self
#<<(hash) ⇒ self
#<<(value) ⇒ self
Adds a field to self
; returns self
:
If the argument is a 2-element Array [header, value]
, a field is added with the given header
and value
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << ['NAME', 'Bat']
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" "NAME":"Bat">
If the argument is a Hash, each key-value
pair is added as a field with header key
and value value
.
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << {NAME: 'Bat', name: 'Bam'}
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" NAME:"Bat" name:"Bam">
Otherwise, the given value
is added as a field with no header.
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row << 'Bag'
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bag">
#==(other) ⇒ Boolean
Returns true
if other
is a /CSV::Row that has the same fields (headers and values) in the same order as self
; otherwise returns false
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
other_row = table[0]
row == other_row # => true
other_row = table[1]
row == other_row # => false
#[](header_or_index, minimum_index = 0)
Alias for #field.
# File 'lib/csv/row.rb', line 215
alias_method :[], :field
#[]=(index, value) ⇒ value
#[]=(header, offset, value) ⇒ value
#[]=(header, value) ⇒ value
value
#[]=(header, offset, value) ⇒ value
#[]=(header, value) ⇒ value
Assigns the field value for the given #index or header
; returns value
.
Assign field value by Integer index:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row[0] = 'Bat'
row[1] = 3
row # => #<CSV::Row "Name":"Bat" "Value":3>
Counts backward from the last column if #index is negative:
row[-1] = 4
row[-2] = 'Bam'
row # => #<CSV::Row "Name":"Bam" "Value":4>
Extends the row with nil:nil
if positive #index is not in the row:
row[4] = 5
row # => #<CSV::Row "Name":"bad" "Value":4 nil:nil nil:nil nil:5>
Raises IndexError if negative #index is too small (too far from zero).
Assign field value by header (first found):
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['Name'] = 'Bat'
row # => #<CSV::Row "Name":"Bat" "Name":"Bar" "Name":"Baz">
Assign field value by header, ignoring offset
leading fields:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['Name', 2] = 4
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":4>
Append new field by (new) header:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row['New'] = 6
row# => #<CSV::Row "Name":"foo" "Value":"0" "New":6>
# File 'lib/csv/row.rb', line 339
def []=(*args) value = args.pop if args.first.is_a? Integer if @row[args.first].nil? # extending past the end with index @row[args.first] = [nil, value] @row.map! { |pair| pair.nil? ? [nil, nil] : pair } else # normal index assignment @row[args.first][1] = value end else index = index(*args) if index.nil? # appending a field self << [args.first, value] else # normal header assignment @row[index][1] = value end end end
#deconstruct ⇒ Array
Returns the new Array suitable for pattern matching containing the values of the row.
# File 'lib/csv/row.rb', line 682
def deconstruct fields end
#deconstruct_keys(keys) ⇒ Hash
Returns the new Hash suitable for pattern matching containing only the keys specified as an argument.
Removes a specified field from self
; returns the 2-element Array [header, value]
if the field exists.
If an Integer argument #index is given, removes and returns the field at offset #index, or returns nil
if the field does not exist:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete(1) # => ["Name", "Bar"]
row.delete(50) # => nil
Otherwise, if the single argument header
is given, removes and returns the first-found field with the given header, of returns a new empty Array if the field does not exist:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete('Name') # => ["Name", "Foo"]
row.delete('NAME') # => []
If argument header
and Integer argument offset
are given, removes and returns the first-found field with the given header whose #index is at least as large as offset
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete('Name', 1) # => ["Name", "Bar"]
row.delete('NAME', 1) # => []
# File 'lib/csv/row.rb', line 451
def delete(header_or_index, minimum_index = 0) if header_or_index.is_a? Integer # by index @row.delete_at(header_or_index) elsif i = index(header_or_index, minimum_index) # by header @row.delete_at(i) else [ ] end end
#delete_if {|header, value| ... } ⇒ self
Removes fields from self
as selected by the block; returns self
.
Removes each field for which the block returns a truthy value:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.delete_if {|header, value| value.start_with?('B') } # => true
row # => #<CSV::Row "Name":"Foo">
row.delete_if {|header, value| header.start_with?('B') } # => false
If no block is given, returns a new Enumerator:
row.delete_if # => #<Enumerator: #<CSV::Row "Name":"Foo">:delete_if>
# File 'lib/csv/row.rb', line 476
def delete_if(&block) return enum_for(__method__) { size } unless block_given? @row.delete_if(&block) self # for chaining end
#dig(index_or_header, *identifiers) ⇒ Object
Finds and returns the object in nested object that is specified by index_or_header
and specifiers
.
The nested objects may be instances of various classes. See Dig Methods
.
Examples:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.dig(1) # => "0"
row.dig('Value') # => "0"
row.dig(5) # => nil
# File 'lib/csv/row.rb', line 715
def dig(index_or_header, *indexes) value = field(index_or_header) if value.nil? nil elsif indexes.empty? value else unless value.respond_to?(:dig) raise TypeError, "#{value.class} does not have \#dig method" end value.dig(*indexes) end end
#each {|header, value| ... } ⇒ self
Also known as: #each_pair
Calls the block with each header-value pair; returns self
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.each {|header, value| p [header, value] }
Output:
["Name", "Foo"]
["Name", "Bar"]
["Name", "Baz"]
If no block is given, returns a new Enumerator:
row.each # => #<Enumerator: #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz">:each>
# File 'lib/csv/row.rb', line 610
def each(&block) return enum_for(__method__) { size } unless block_given? @row.each(&block) self # for chaining end
#each_pair(&block)
Alias for #each.
# File 'lib/csv/row.rb', line 618
alias_method :each_pair, :each
#fetch(header) ⇒ value
#fetch(header, default) ⇒ value
#fetch(header) {|row| ... } ⇒ value
value
#fetch(header, default) ⇒ value
#fetch(header) {|row| ... } ⇒ value
Returns the field value as specified by header
.
With the single argument header
, returns the field value for that header (first found):
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name') # => "Foo"
Raises exception KeyError
if the header does not exist.
With arguments header
and default
given, returns the field value for the header (first found) if the header exists, otherwise returns default
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name', '') # => "Foo"
row.fetch(:nosuch, '') # => ""
With argument header
and a block given, returns the field value for the header (first found) if the header exists; otherwise calls the block and returns its return value:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fetch('Name') {|header| fail 'Cannot happen' } # => "Foo"
row.fetch(:nosuch) {|header| "Header '#{header} not found'" } # => "Header 'nosuch not found'"
# File 'lib/csv/row.rb', line 258
def fetch(header, *varargs) raise ArgumentError, "Too many arguments" if varargs.length > 1 pair = @row.assoc(header) if pair pair.last else if block_given? yield header elsif varargs.empty? raise KeyError, "key not found: #{header}" else varargs.first end end end
#field(index) ⇒ value
#field(header) ⇒ value
#field(header, offset) ⇒ value
Also known as: #[]
value
#field(header) ⇒ value
#field(header, offset) ⇒ value
Returns the field value for the given #index or header
.
Fetch field value by Integer index:
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field(0) # => "foo"
row.field(1) # => "bar"
Counts backward from the last column if #index is negative:
row.field(-1) # => "0"
row.field(-2) # => "foo"
Returns nil
if #index is out of range:
row.field(2) # => nil
row.field(-3) # => nil
Fetch field value by header (first found):
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field('Name') # => "Foo"
Fetch field value by header, ignoring offset
leading fields:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field('Name', 2) # => "Baz"
Returns nil
if the header does not exist.
# File 'lib/csv/row.rb', line 203
def field(header_or_index, minimum_index = 0) # locate the pair finder = (header_or_index.is_a?(Integer) || header_or_index.is_a?(Range)) ? :[] : :assoc pair = @row[minimum_index..-1].public_send(finder, header_or_index) # return the field if we have a pair if pair.nil? nil else header_or_index.is_a?(Range) ? pair.map(&:last) : pair.last end end
#field?(value) ⇒ Boolean
#fields(*specifiers) ⇒ array_of_fields
Also known as: #values_at
Returns field values per the given specifiers
, which may be any mixture of:
-
Integer index.
-
Range of Integer indexes.
-
2-element Array containing a header and offset.
-
Header.
-
Range of headers.
For specifier
in one of the first four cases above, returns the result of self.field(specifier)
; see #field.
Although there may be any number of specifiers
, the examples here will illustrate one at a time.
When the specifier is an Integer #index, returns self.field(index)
L
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fields(1) # => ["Bar"]
When the specifier is a Range of Integers range
, returns self.field(range)
:
row.fields(1..2) # => ["Bar", "Baz"]
When the specifier is a 2-element Array array
, returns self.field(array)
L
row.fields('Name', 1) # => ["Foo", "Bar"]
When the specifier is a header header
, returns self.field(header)
L
row.fields('Name') # => ["Foo"]
When the specifier is a Range of headers range
, forms a new Range new_range
from the indexes of range.start
and range.end
, and returns self.field(new_range)
:
source = "Name,NAME,name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.fields('Name'..'NAME') # => ["Foo", "Bar"]
Returns all fields if no argument given:
row.fields # => ["Foo", "Bar", "Baz"]
# File 'lib/csv/row.rb', line 530
def fields(*headers_and_or_indices) if headers_and_or_indices.empty? # return all fields--no arguments @row.map(&:last) else # or work like values_at() all = [] headers_and_or_indices.each do |h_or_i| if h_or_i.is_a? Range index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin : index(h_or_i.begin) index_end = h_or_i.end.is_a?(Integer) ? h_or_i.end : index(h_or_i.end) new_range = h_or_i.exclude_end? ? (index_begin...index_end) : (index_begin..index_end) all.concat(fields.values_at(new_range)) else all << field(*Array(h_or_i)) end end return all end end
#has_key?(header) ⇒ Boolean
Also known as: #include?, #key?, #member?, #header?
Returns true
if there is a field with the given header
, false
otherwise.
# File 'lib/csv/row.rb', line 279
def has_key?(header) !!@row.assoc(header) end
#header?(header)
Alias for #has_key?.
# File 'lib/csv/row.rb', line 285
alias_method :header?, :has_key?
#headers ⇒ array_of_headers
# File 'lib/csv/row.rb', line 160
def headers @row.map(&:first) end
#include?(header)
Alias for #has_key?.
# File 'lib/csv/row.rb', line 282
alias_method :include?, :has_key?
#index(header) ⇒ index
#index(header, offset) ⇒ index
Returns the index for the given header, if it exists; otherwise returns nil
.
With the single argument header
, returns the index of the first-found field with the given header
:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.index('Name') # => 0
row.index('NAME') # => nil
With arguments header
and offset
, returns the index of the first-found field with given header
, but ignoring the first offset
fields:
row.index('Name', 1) # => 1
row.index('Name', 3) # => nil
# File 'lib/csv/row.rb', line 573
def index(header, minimum_index = 0) # find the pair index = headers[minimum_index..-1].index(header) # return the index at the right offset, if we found one index.nil? ? nil : index + minimum_index end
#initialize_copy(other_row) ⇒ self
Calls superclass method.
# File 'lib/csv/row.rb', line 130
def initialize_copy(other) super_return_value = super @row = @row.collect(&:dup) super_return_value end
#inspect ⇒ String
# File 'lib/csv/row.rb', line 740
def inspect str = ["#<", self.class.to_s] each do |header, field| str << " " << (header.is_a?(Symbol) ? header.to_s : header.inspect) << ":" << field.inspect end str << ">" begin str.join('') rescue # any encoding error str.map do |s| e = Encoding::Converter.asciicompat_encoding(s.encoding) e ? s.encode(e) : s.force_encoding("ASCII-8BIT") end.join('') end end
#key?(header)
Alias for #has_key?.
# File 'lib/csv/row.rb', line 283
alias_method :key?, :has_key?
#member?(header)
Alias for #has_key?.
# File 'lib/csv/row.rb', line 284
alias_method :member?, :has_key?
#push(*values) ⇒ self
# File 'lib/csv/row.rb', line 410
def push(*args) args.each { |arg| self << arg } self # for chaining end
#to_ary
[ GitHub ]# File 'lib/csv/row.rb', line 675
alias_method :to_ary, :to_a
#to_csv ⇒ csv_string
Also known as: #to_s
# File 'lib/csv/row.rb', line 694
def to_csv(** ) fields.to_csv(** ) end
#to_h ⇒ Hash
Also known as: #to_hash
Returns the new Hash formed by adding each header-value pair in self
as a key-value pair in the Hash.
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_h # => {"Name"=>"foo", "Value"=>"0"}
Header order is preserved, but repeated headers are ignored:
source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_h # => {"Name"=>"Foo"}
#to_hash
Alias for #to_h.
# File 'lib/csv/row.rb', line 660
alias_method :to_hash, :to_h
#to_s(**options)
Alias for #to_csv.
# File 'lib/csv/row.rb', line 697
alias_method :to_s, :to_csv
#values_at(*headers_and_or_indices)
Alias for #fields.
# File 'lib/csv/row.rb', line 551
alias_method :values_at, :fields