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FasterCSV::Row

A FasterCSV::Row is part Array and part Hash. It retains an order for the fields and allows duplicates just as an Array would, but also allows you to access fields by name just as you could if they were in a Hash.

All rows returned by FasterCSV will be constructed from this class, if header row processing is activated.

Attributes

row[R]

Internal data format used to compare equality.

Public Class Methods

new(headers, fields, header_row = false) click to toggle source

Construct a new FasterCSV::Row from headers and fields, which are expected to be Arrays. If one Array is shorter than the other, it will be padded with nil objects.

The optional header_row parameter can be set to true to indicate, via FasterCSV::Row.header_row?() and FasterCSV::Row.field_row?(), that this is a header row. Otherwise, the row is assumes to be a field row.

A FasterCSV::Row object supports the following Array methods through delegation:

  • empty?()

  • length()

  • size()

     # File lib/faster_csv.rb, line 130
130:       def initialize(headers, fields, header_row = false)
131:         @header_row = header_row
132: 
133:         # handle extra headers or fields
134:         @row = if headers.size > fields.size
135:           headers.zip(fields)
136:         else
137:           fields.zip(headers).map { |pair| pair.reverse }
138:         end
139:       end

Public Instance Methods

<<( field ) <<( header_and_field_array ) <<( header_and_field_hash ) click to toggle source

If a two-element Array is provided, it is assumed to be a header and field and the pair is appended. A Hash works the same way with the key being the header and the value being the field. Anything else is assumed to be a lone field which is appended with a nil header.

This method returns the row for chaining.

     # File lib/faster_csv.rb, line 234
234:       def <<(arg)
235:         if arg.is_a?(Array) and arg.size == 2  # appending a header and name
236:           @row << arg
237:         elsif arg.is_a?(Hash)                  # append header and name pairs
238:           arg.each { |pair| @row << pair }
239:         else                                   # append field value
240:           @row << [nil, arg]
241:         end
242: 
243:         self  # for chaining
244:       end
==(other) click to toggle source

Returns true if this row contains the same headers and fields in the same order as other.

     # File lib/faster_csv.rb, line 371
371:       def ==(other)
372:         @row == other.row
373:       end
[](header_or_index, minimum_index = 0) click to toggle source
Alias for: field
[]=( header, value ) []=( header, offset, value ) []=( index, value ) click to toggle source

Looks up the field by the semantics described in FasterCSV::Row.field() and assigns the value.

Assigning past the end of the row with an index will set all pairs between to [nil, nil]. Assigning to an unused header appends the new pair.

     # File lib/faster_csv.rb, line 201
201:       def []=(*args)
202:         value = args.pop
203: 
204:         if args.first.is_a? Integer
205:           if @row[args.first].nil?  # extending past the end with index
206:             @row[args.first] = [nil, value]
207:             @row.map! { |pair| pair.nil? ? [nil, nil] : pair }
208:           else                      # normal index assignment
209:             @row[args.first][1] = value
210:           end
211:         else
212:           index = index(*args)
213:           if index.nil?             # appending a field
214:             self << [args.first, value]
215:           else                      # normal header assignment
216:             @row[index][1] = value
217:           end
218:         end
219:       end
delete( header ) delete( header, offset ) delete( index ) click to toggle source

Used to remove a pair from the row by header or index. The pair is located as described in FasterCSV::Row.field(). The deleted pair is returned, or nil if a pair could not be found.

     # File lib/faster_csv.rb, line 269
269:       def delete(header_or_index, minimum_index = 0)
270:         if header_or_index.is_a? Integer                 # by index
271:           @row.delete_at(header_or_index)
272:         elsif i = index(header_or_index, minimum_index)  # by header
273:           @row.delete_at(i)
274:         else
275:           [ ]
276:         end
277:       end
delete_if(&block) click to toggle source

The provided block is passed a header and field for each pair in the row and expected to return true or false, depending on whether the pair should be deleted.

This method returns the row for chaining.

     # File lib/faster_csv.rb, line 286
286:       def delete_if(&block)
287:         @row.delete_if(&block)
288: 
289:         self  # for chaining
290:       end
each(&block) click to toggle source

Yields each pair of the row as header and field tuples (much like iterating over a Hash).

Support for Enumerable.

This method returns the row for chaining.

     # File lib/faster_csv.rb, line 361
361:       def each(&block)
362:         @row.each(&block)
363: 
364:         self  # for chaining
365:       end
field( header ) field( header, offset ) field( index ) click to toggle source

This method will fetch the field value by header or index. If a field is not found, nil is returned.

When provided, offset ensures that a header match occurrs on or later than the offset index. You can use this to find duplicate headers, without resorting to hard-coding exact indices.

     # File lib/faster_csv.rb, line 178
178:       def field(header_or_index, minimum_index = 0)
179:         # locate the pair
180:         finder = header_or_index.is_a?(Integer) ? :[] : :assoc
181:         pair   = @row[minimum_index..1].send(finder, header_or_index)
182: 
183:         # return the field if we have a pair
184:         pair.nil? ? nil : pair.last
185:       end
Also aliased as: []
field?(data) click to toggle source

Returns true if data matches a field in this row, and false otherwise.

     # File lib/faster_csv.rb, line 347
347:       def field?(data)
348:         fields.include? data
349:       end
field_row?() click to toggle source

Returns true if this is a field row.

     # File lib/faster_csv.rb, line 156
156:       def field_row?
157:         not header_row?
158:       end
fields(*headers_and_or_indices) click to toggle source

This method accepts any number of arguments which can be headers, indices, Ranges of either, or two-element Arrays containing a header and offset. Each argument will be replaced with a field lookup as described in FasterCSV::Row.field().

If called with no arguments, all fields are returned.

     # File lib/faster_csv.rb, line 300
300:       def fields(*headers_and_or_indices)
301:         if headers_and_or_indices.empty?  # return all fields--no arguments
302:           @row.map { |pair| pair.last }
303:         else                              # or work like values_at()
304:           headers_and_or_indices.inject(Array.new) do |all, h_or_i|
305:             all + if h_or_i.is_a? Range
306:               index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin :
307:                                                           index(h_or_i.begin)
308:               index_end   = h_or_i.end.is_a?(Integer)   ? h_or_i.end :
309:                                                           index(h_or_i.end)
310:               new_range   = h_or_i.exclude_end? ? (index_begin...index_end) :
311:                                                   (index_begin..index_end)
312:               fields.values_at(new_range)
313:             else
314:               [field(*Array(h_or_i))]
315:             end
316:           end
317:         end
318:       end
Also aliased as: values_at
header?(name) click to toggle source

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

     # File lib/faster_csv.rb, line 338
338:       def header?(name)
339:         headers.include? name
340:       end
Also aliased as: include?
header_row?() click to toggle source

Returns true if this is a header row.

     # File lib/faster_csv.rb, line 151
151:       def header_row?
152:         @header_row
153:       end
headers() click to toggle source

Returns the headers of this row.

     # File lib/faster_csv.rb, line 161
161:       def headers
162:         @row.map { |pair| pair.first }
163:       end
include?(name) click to toggle source
Alias for: header?
index( header ) index( header, offset ) click to toggle source

This method will return the index of a field with the provided header. The offset can be used to locate duplicate header names, as described in FasterCSV::Row.field().

     # File lib/faster_csv.rb, line 330
330:       def index(header, minimum_index = 0)
331:         # find the pair
332:         index = headers[minimum_index..1].index(header)
333:         # return the index at the right offset, if we found one
334:         index.nil? ? nil : index + minimum_index
335:       end
inspect() click to toggle source

A summary of fields, by header.

     # File lib/faster_csv.rb, line 395
395:       def inspect
396:         str = "#<#{self.class}"
397:         each do |header, field|
398:           str << " #{header.is_a?(Symbol) ? header.to_s : header.inspect}:" <<
399:                  field.inspect
400:         end
401:         str << ">"
402:       end
push(*args) click to toggle source

A shortcut for appending multiple fields. Equivalent to:

  args.each { |arg| faster_csv_row << arg }

This method returns the row for chaining.

     # File lib/faster_csv.rb, line 253
253:       def push(*args)
254:         args.each { |arg| self << arg }
255: 
256:         self  # for chaining
257:       end
to_csv(options = Hash.new) click to toggle source

Returns the row as a CSV String. Headers are not used. Equivalent to:

  faster_csv_row.fields.to_csv( options )
     # File lib/faster_csv.rb, line 389
389:       def to_csv(options = Hash.new)
390:         fields.to_csv(options)
391:       end
Also aliased as: to_s
to_hash() click to toggle source

Collapses the row into a simple Hash. Be warning that this discards field order and clobbers duplicate fields.

     # File lib/faster_csv.rb, line 379
379:       def to_hash
380:         # flatten just one level of the internal Array
381:         Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]
382:       end
to_s(options = Hash.new) click to toggle source
Alias for: to_csv
values_at(*headers_and_or_indices) click to toggle source
Alias for: fields

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