CSV::Row

Class

CSV::Row

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.:

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>

Attributes

row

Read

Internal data format used to compare equality.

Class Methods

CSV::Row.new(headers, fields, header_row = false) → csv_row

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 105
def initialize(headers, fields, header_row = false)
  @header_row = header_row
  headers.each { |h| h.freeze if h.is_a? String }

  # handle extra headers or fields
  @row = if headers.size >= fields.size
    headers.zip(fields)
  else
    fields.zip(headers).each(&:reverse!)
  end
end

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 Methods

row << [header, value] → self

row << hash → self

row << value → self

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 389
def <<(arg)
  if arg.is_a?(Array) and arg.size == 2  # appending a header and name
    @row << arg
  elsif arg.is_a?(Hash)                  # append header and name pairs
    arg.each { |pair| @row << pair }
  else                                   # append field value
    @row << [nil, arg]
  end

  self  # for chaining
end

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">

row == other → true or false

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 633
def ==(other)
  return @row == other.row if other.is_a? CSV::Row
  @row == other
end

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)

lib/csv/row.rb View on GitHub

An alias for field

row[index] = value → value

row[header, offset] = value → value

row[header] = value → value

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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>

row.deconstruct → array

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 682
def deconstruct
  fields
end

Returns the new Array suitable for pattern matching containing the values of the row.

row.deconstruct_keys(keys) → hash

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 667
def deconstruct_keys(keys)
  if keys.nil?
    to_h
  else
    keys.to_h { |key| [key, self[key]] }
  end
end

Returns the new Hash suitable for pattern matching containing only the keys specified as an argument.

delete(index) → [header, value] or nil

delete(header) → [header, value] or empty_array

delete(header, offset) → [header, value] or empty_array

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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) # => []

row.delete_if {|header, value| ... } → self

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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>

row.dig(index_or_header, *identifiers) → object

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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

row.each {|header, value| ... } → self

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 610
def each(&block)
  return enum_for(__method__) { size } unless block_given?

  @row.each(&block)

  self  # for chaining
end

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>

each_pair(&block)

lib/csv/row.rb View on GitHub

An alias for each

fetch(header) → value

fetch(header, default) → value

fetch(header) {|row| ... } → value

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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'"

field(index) → value

field(header) → value

field(header, offset) → value

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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.

row.field?(value) → true or false

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 589
def field?(data)
  fields.include? data
end

Returns true if value is a field in this row, false otherwise:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.field?('Bar') # => true
row.field?('BAR') # => false

row.field_row? → true or false

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 148
def field_row?
  not header_row?
end

Returns true if this is a field row, false otherwise.

self.fields(*specifiers) → array_of_fields

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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"]

row.has_key?(header) → true or false

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 279
def has_key?(header)
  !!@row.assoc(header)
end

Returns true if there is a field with the given header, false otherwise.

header?(header)

lib/csv/row.rb View on GitHub

An alias for has_key?

row.header_row? → true or false

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 140
def header_row?
  @header_row
end

Returns true if this is a header row, false otherwise.

row.headers → array_of_headers

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 160
def headers
  @row.map(&:first)
end

Returns the headers for this row:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table.first
row.headers # => ["Name", "Value"]

include?(header)

lib/csv/row.rb View on GitHub

An alias for has_key?

index(header) → index

index(header, offset) → index

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

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

row.initialize_copy(other_row) → self

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 130
def initialize_copy(other)
  super_return_value = super
  @row = @row.collect(&:dup)
  super_return_value
end

Calls superclass method.

row.inspect → string

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/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

Returns an ASCII-compatible String showing:

Class CSV::Row.
Header-value pairs.

Example:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.inspect # => "#<CSV::Row \"Name\":\"foo\" \"Value\":\"0\">"

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 410
def push(*args)
  args.each { |arg| self << arg }

  self  # for chaining
end

Appends each of the given values to self as a field; returns self:

source = "Name,Name,Name\nFoo,Bar,Baz\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.push('Bat', 'Bam')
row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bat" nil:"Bam">

row.to_csv → csv_string

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 694
def to_csv(**options)
  fields.to_csv(**options)
end

Returns the row as a CSV String. Headers are not included:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
row = table[0]
row.to_csv # => "foo,0\n"

row.to_h → hash

lib/csv/row.rb View on GitHub

          
            # File tmp/rubies/ruby-3.2.0/lib/csv/row.rb, line 653
def to_h
  hash = {}
  each do |key, _value|
    hash[key] = self[key] unless hash.key?(key)
  end
  hash
end

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"}

CSV::Row

CSV::Row

Instance Methods

Creating a CSV::Row Instance

Headers

Accessing Fields

row

CSV::Row.new(headers, fields, header_row = false) → csv_row

row << [header, value] → self

row << hash → self

row << value → self

row == other → true or false

[](header_or_index, minimum_index = 0)

row[index] = value → value

row[header, offset] = value → value

row[header] = value → value

row.deconstruct → array

row.deconstruct_keys(keys) → hash

delete(index) → [header, value] or nil

delete(header) → [header, value] or empty_array

delete(header, offset) → [header, value] or empty_array

row.delete_if {|header, value| ... } → self

row.dig(index_or_header, *identifiers) → object

row.each {|header, value| ... } → self

each_pair(&block)

fetch(header) → value

fetch(header, default) → value

fetch(header) {|row| ... } → value

field(index) → value

field(header) → value

field(header, offset) → value

row.field?(value) → true or false

row.field_row? → true or false

self.fields(*specifiers) → array_of_fields

row.has_key?(header) → true or false

header?(header)

row.header_row? → true or false

row.headers → array_of_headers

include?(header)

index(header) → index

index(header, offset) → index

row.initialize_copy(other_row) → self

row.inspect → string

key?(header)

member?(header)

row.push(*values) → self

row.to_csv → csv_string

row.to_h → hash

to_hash

to_s(**options)

values_at(*headers_and_or_indices)