зеркало из https://github.com/github/ruby.git
[ruby/csv] Split recipes into three pages: parsing, generating, filtering (#184)
Co-authored-by: Sutou Kouhei <kou@clear-code.com> https://github.com/ruby/csv/commit/f0bab6a592
This commit is contained in:
Burdette Lamar
Sutou Kouhei
Родитель
3cfb63fcd8
Коммит
c5fcafd2fd
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@ -0,0 +1,156 @@
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== Recipes for Filtering \CSV
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For other recipes, see {Recipes for CSV}[./recipes_rdoc.html].
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All code snippets on this page assume that the following has been executed:
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require 'csv'
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=== Contents
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- {Source and Output Formats}[#label-Source+and+Output+Formats]
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- {Filtering String to String}[#label-Filtering+String+to+String]
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- {Recipe: Filter String to String with Headers}[#label-Recipe-3A+Filter+String+to+String+with+Headers]
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- {Recipe: Filter String to String Without Headers}[#label-Recipe-3A+Filter+String+to+String+Without+Headers]
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- {Filtering String to IO Stream}[#label-Filtering+String+to+IO+Stream]
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- {Recipe: Filter String to IO Stream with Headers}[#label-Recipe-3A+Filter+String+to+IO+Stream+with+Headers]
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- {Recipe: Filter String to IO Stream Without Headers}[#label-Recipe-3A+Filter+String+to+IO+Stream+Without+Headers]
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- {Filtering IO Stream to String}[#label-Filtering+IO+Stream+to+String]
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- {Recipe: Filter IO Stream to String with Headers}[#label-Recipe-3A+Filter+IO+Stream+to+String+with+Headers]
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- {Recipe: Filter IO Stream to String Without Headers}[#label-Recipe-3A+Filter+IO+Stream+to+String+Without+Headers]
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- {Filtering IO Stream to IO Stream}[#label-Filtering+IO+Stream+to+IO+Stream]
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- {Recipe: Filter IO Stream to IO Stream with Headers}[#label-Recipe-3A+Filter+IO+Stream+to+IO+Stream+with+Headers]
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- {Recipe: Filter IO Stream to IO Stream Without Headers}[#label-Recipe-3A+Filter+IO+Stream+to+IO+Stream+Without+Headers]
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=== Source and Output Formats
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You can use a Unix-style "filter" for \CSV data.
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The filter reads source \CSV data and writes output \CSV data as modified by the filter.
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The input and output \CSV data may be any mixture of \Strings and \IO streams.
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==== Filtering \String to \String
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You can filter one \String to another, with or without headers.
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===== Recipe: Filter \String to \String with Headers
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Use class method CSV.filter with option +headers+ to filter a \String to another \String:
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in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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out_string = ''
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CSV.filter(in_string, out_string, headers: true) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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===== Recipe: Filter \String to \String Without Headers
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Use class method CSV.filter without option +headers+ to filter a \String to another \String:
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in_string = "foo,0\nbar,1\nbaz,2\n"
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out_string = ''
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CSV.filter(in_string, out_string) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filtering \String to \IO Stream
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You can filter a \String to an \IO stream, with or without headers.
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===== Recipe: Filter \String to \IO Stream with Headers
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Use class method CSV.filter with option +headers+ to filter a \String to an \IO stream:
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in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.open(path, 'w') do |out_io|
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CSV.filter(in_string, out_io, headers: true) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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p File.read(path) # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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===== Recipe: Filter \String to \IO Stream Without Headers
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Use class method CSV.filter without option +headers+ to filter a \String to an \IO stream:
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in_string = "foo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.open(path, 'w') do |out_io|
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CSV.filter(in_string, out_io) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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p File.read(path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filtering \IO Stream to \String
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You can filter an \IO stream to a \String, with or without headers.
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===== Recipe: Filter \IO Stream to \String with Headers
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Use class method CSV.filter with option +headers+ to filter an \IO stream to a \String:
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in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.write(path, in_string)
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out_string = ''
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File.open(path, headers: true) do |in_io|
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CSV.filter(in_io, out_string, headers: true) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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===== Recipe: Filter \IO Stream to \String Without Headers
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Use class method CSV.filter without option +headers+ to filter an \IO stream to a \String:
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in_string = "foo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.write(path, in_string)
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out_string = ''
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File.open(path) do |in_io|
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CSV.filter(in_io, out_string) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filtering \IO Stream to \IO Stream
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You can filter an \IO stream to another \IO stream, with or without headers.
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===== Recipe: Filter \IO Stream to \IO Stream with Headers
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Use class method CSV.filter with option +headers+ to filter an \IO stream to another \IO stream:
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in_path = 't.csv'
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in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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File.write(in_path, in_string)
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out_path = 'u.csv'
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File.open(in_path) do |in_io|
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File.open(out_path, 'w') do |out_io|
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CSV.filter(in_io, out_io, headers: true) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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end
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p File.read(out_path) # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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===== Recipe: Filter \IO Stream to \IO Stream Without Headers
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Use class method CSV.filter without option +headers+ to filter an \IO stream to another \IO stream:
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in_path = 't.csv'
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in_string = "foo,0\nbar,1\nbaz,2\n"
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File.write(in_path, in_string)
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out_path = 'u.csv'
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File.open(in_path) do |in_io|
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File.open(out_path, 'w') do |out_io|
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CSV.filter(in_io, out_io) do |row|
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row[0] = row[0].upcase
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row[1] *= 4
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end
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end
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end
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p File.read(out_path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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@ -0,0 +1,113 @@
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== Recipes for Generating \CSV
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For other recipes, see {Recipes for CSV}[./recipes_rdoc.html].
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All code snippets on this page assume that the following has been executed:
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require 'csv'
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=== Contents
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- {Output Formats}[#label-Output+Formats]
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- {Generating to a String}[#label-Generating+to+a+String]
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- {Recipe: Generate to String with Headers}[#label-Recipe-3A+Generate+to+String+with+Headers]
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- {Recipe: Generate to String Without Headers}[#label-Recipe-3A+Generate+to+String+Without+Headers]
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- {Generating to a File}[#label-Generating+to+a+File]
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- {Recipe: Generate to File with Headers}[#label-Recipe-3A+Generate+to+File+with+Headers]
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- {Recipe: Generate to File Without Headers}[#label-Recipe-3A+Generate+to+File+Without+Headers]
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- {Generating to IO an Stream}[#label-Generating+to+an+IO+Stream]
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- {Recipe: Generate to IO Stream with Headers}[#label-Recipe-3A+Generate+to+IO+Stream+with+Headers]
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- {Recipe: Generate to IO Stream Without Headers}[#label-Recipe-3A+Generate+to+IO+Stream+Without+Headers]
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=== Output Formats
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You can generate \CSV output to a \String, to a \File (via its path), or to an \IO stream.
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==== Generating to a \String
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You can generate \CSV output to a \String, with or without headers.
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===== Recipe: Generate to \String with Headers
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Use class method CSV.generate with option +headers+ to generate to a \String.
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This example uses method CSV#<< to append the rows
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that are to be generated:
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output_string = CSV.generate('', headers: ['Name', 'Value'], write_headers: true) do |csv|
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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output_string # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
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===== Recipe: Generate to \String Without Headers
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Use class method CSV.generate without option +headers+ to generate to a \String.
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This example uses method CSV#<< to append the rows
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that are to be generated:
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output_string = CSV.generate do |csv|
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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output_string # => "Foo,0\nBar,1\nBaz,2\n"
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==== Generating to a \File
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You can generate /CSV data to a \File, with or without headers.
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===== Recipe: Generate to \File with Headers
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Use class method CSV.open with option +headers+ generate to a \File.
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This example uses method CSV#<< to append the rows
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that are to be generated:
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path = 't.csv'
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CSV.open(path, 'w', headers: ['Name', 'Value'], write_headers: true) do |csv|
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
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===== Recipe: Generate to \File Without Headers
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Use class method CSV.open without option +headers+ to generate to a \File.
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This example uses method CSV#<< to append the rows
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that are to be generated:
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path = 't.csv'
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CSV.open(path, 'w') do |csv|
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
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==== Generating to an \IO Stream
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You can generate \CSV data to an \IO stream, with or without headers.
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==== Recipe: Generate to \IO Stream with Headers
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Use class method CSV.new with option +headers+ to generate \CSV data to an \IO stream:
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path = 't.csv'
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File.open(path, 'w') do |file|
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csv = CSV.new(file, headers: ['Name', 'Value'], write_headers: true)
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
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===== Recipe: Generate to \IO Stream Without Headers
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Use class method CSV.new without option +headers+ to generate \CSV data to an \IO stream:
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path = 't.csv'
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File.open(path, 'w') do |file|
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csv = CSV.new(file)
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csv << ['Foo', 0]
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csv << ['Bar', 1]
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csv << ['Baz', 2]
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end
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p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
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@ -1,11 +1,13 @@
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== Recipes
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== Recipes for Parsing \CSV
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For other recipes, see {Recipes for CSV}[./recipes_rdoc.html].
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All code snippets on this page assume that the following has been executed:
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require 'csv'
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=== Contents
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- {Parsing: Source Formats}[#label-Parsing-3A+Source+Formats]
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- {Source Formats}[#label-Source+Formats]
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- {Parsing from a String}[#label-Parsing+from+a+String]
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- {Recipe: Parse from String with Headers}[#label-Recipe-3A+Parse+from+String+with+Headers]
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- {Recipe: Parse from String Without Headers}[#label-Recipe-3A+Parse+from+String+Without+Headers]
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@ -15,7 +17,7 @@ All code snippets on this page assume that the following has been executed:
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- {Parsing from an IO Stream}[#label-Parsing+from+an+IO+Stream]
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- {Recipe: Parse from IO Stream with Headers}[#label-Recipe-3A+Parse+from+IO+Stream+with+Headers]
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- {Recipe: Parse from IO Stream Without Headers}[#label-Recipe-3A+Parse+from+IO+Stream+Without+Headers]
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- {Parsing: Field Converters}[#label-Parsing-3A+Field+Converters]
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- {Converting Fields}[#label-Converting+Fields]
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- {Converting Fields to Objects}[#label-Converting+Fields+to+Objects]
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- {Recipe: Convert Fields to Integers}[#label-Recipe-3A+Convert+Fields+to+Integers]
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- {Recipe: Convert Fields to Floats}[#label-Recipe-3A+Convert+Fields+to+Floats]
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@ -29,31 +31,16 @@ All code snippets on this page assume that the following has been executed:
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- {Using Multiple Field Converters}[#label-Using+Multiple+Field+Converters]
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- {Recipe: Specify Multiple Field Converters in Option :converters}[#label-Recipe-3A+Specify+Multiple+Field+Converters+in+Option+-3Aconverters]
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- {Recipe: Specify Multiple Field Converters in a Custom Converter List}[#label-Recipe-3A+Specify+Multiple+Field+Converters+in+a+Custom+Converter+List]
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- {Generating: Output Formats}[#label-Generating-3A+Output+Formats]
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- {Generating to a String}[#label-Generating+to+a+String]
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- {Recipe: Generate to String with Headers}[#label-Recipe-3A+Generate+to+String+with+Headers]
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- {Recipe: Generate to String Without Headers}[#label-Recipe-3A+Generate+to+String+Without+Headers]
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- {Generating to a File}[#label-Generating+to+a+File]
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- {Recipe: Generate to File with Headers}[#label-Recipe-3A+Generate+to+File+with+Headers]
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- {Recipe: Generate to File Without Headers}[#label-Recipe-3A+Generate+to+File+Without+Headers]
|
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- {Generating to IO an Stream}[#label-Generating+to+an+IO+Stream]
|
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- {Recipe: Generate to IO Stream with Headers}[#label-Recipe-3A+Generate+to+IO+Stream+with+Headers]
|
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- {Recipe: Generate to IO Stream Without Headers}[#label-Recipe-3A+Generate+to+IO+Stream+Without+Headers]
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- {Filtering: Source and Output Formats}[#label-Filtering-3A+Source+and+Output+Formats]
|
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- {Filtering String to String}[#label-Filtering+String+to+String]
|
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- {Recipe: Filter String to String with Headers}[#label-Recipe-3A+Filter+String+to+String+with+Headers]
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- {Recipe: Filter String to String Without Headers}[#label-Recipe-3A+Filter+String+to+String+Without+Headers]
|
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- {Filtering String to IO Stream}[#label-Filtering+String+to+IO+Stream]
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- {Recipe: Filter String to IO Stream with Headers}[#label-Recipe-3A+Filter+String+to+IO+Stream+with+Headers]
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- {Recipe: Filter String to IO Stream Without Headers}[#label-Recipe-3A+Filter+String+to+IO+Stream+Without+Headers]
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- {Filtering IO Stream to String}[#label-Filtering+IO+Stream+to+String]
|
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- {Recipe: Filter IO Stream to String with Headers}[#label-Recipe-3A+Filter+IO+Stream+to+String+with+Headers]
|
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- {Recipe: Filter IO Stream to String Without Headers}[#label-Recipe-3A+Filter+IO+Stream+to+String+Without+Headers]
|
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- {Filtering IO Stream to IO Stream}[#label-Filtering+IO+Stream+to+IO+Stream]
|
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- {Recipe: Filter IO Stream to IO Stream with Headers}[#label-Recipe-3A+Filter+IO+Stream+to+IO+Stream+with+Headers]
|
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- {Recipe: Filter IO Stream to IO Stream Without Headers}[#label-Recipe-3A+Filter+IO+Stream+to+IO+Stream+Without+Headers]
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- {Converting Headers}[#label-Converting+Headers]
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- {Recipe: Convert Headers to Lowercase}[#label-Recipe-3A+Convert+Headers+to+Lowercase]
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- {Recipe: Convert Headers to Symbols}[#label-Recipe-3A+Convert+Headers+to+Symbols]
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- {Recipe: Filter Header Strings}[#label-Recipe-3A+Filter+Header+Strings]
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- {Recipe: Register Header Converters}[#label-Recipe-3A+Register+Header+Converters]
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- {Using Multiple Header Converters}[#label-Using+Multiple+Header+Converters]
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- {Recipe: Specify Multiple Header Converters in Option :header_converters}[#label-Recipe-3A+Specify+Multiple+Header+Converters+in+Option+-3Aheader_converters]
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- {Recipe: Specify Multiple Header Converters in a Custom Header Converter List}[#label-Recipe-3A+Specify+Multiple+Header+Converters+in+a+Custom+Header+Converter+List]
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=== Parsing: Source Formats
|
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=== Source Formats
|
||||
|
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You can parse \CSV data from a \String, from a \File (via its path), or from an \IO stream.
|
||||
|
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@ -177,7 +164,7 @@ Output:
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["bar", "1"]
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["baz", "2"]
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=== Parsing: Field Converters
|
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=== Converting Fields
|
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|
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You can use field converters to change parsed \String fields into other objects,
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or to otherwise modify the \String fields.
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@ -267,6 +254,9 @@ that strips whitespace from each field value:
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Register a custom field converter, assigning it a name;
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then refer to the converter by its name:
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rational_converter = proc do |field, field_context|
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field_context.index == 1 ? field.to_r : field
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end
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CSV::Converters[:rational] = rational_converter
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source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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parsed = CSV.parse(source, headers: true, converters: :rational)
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@ -296,230 +286,68 @@ Apply multiple field converters by defining and registering a custom converter l
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parsed['Name'] # => ["foo", "bar", "baz"]
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parsed['Value'] # => [0, 1.0, 2.0]
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=== Generating: Output Formats
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=== Converting Headers
|
||||
|
||||
You can generate \CSV output to a \String, to a \File (via its path), or to an \IO stream.
|
||||
You can use header converters to modify parsed \String headers.
|
||||
|
||||
==== Generating to a \String
|
||||
Built-in header converters include:
|
||||
- <tt>:symbol</tt>: converts \String header to \Symbol.
|
||||
- <tt>:downcase</tt>: converts \String header to lowercase.
|
||||
|
||||
You can generate \CSV output to a \String, with or without headers.
|
||||
You can also define header converters to otherwise modify header \Strings.
|
||||
|
||||
===== Recipe: Generate to \String with Headers
|
||||
==== Recipe: Convert Headers to Lowercase
|
||||
|
||||
Use class method CSV.generate with option +headers+ to generate to a \String.
|
||||
Convert headers to lowercase using built-in converter <tt>:downcase</tt>:
|
||||
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: :downcase)
|
||||
parsed.headers # => ["name", "value"]
|
||||
|
||||
This example uses method CSV#<< to append the rows
|
||||
that are to be generated:
|
||||
output_string = CSV.generate('', headers: ['Name', 'Value'], write_headers: true) do |csv|
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
output_string # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
|
||||
==== Recipe: Convert Headers to Symbols
|
||||
|
||||
===== Recipe: Generate to \String Without Headers
|
||||
Convert headers to downcased Symbols using built-in converter <tt>:symbol</tt>:
|
||||
source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: :symbol)
|
||||
parsed.headers # => [:name, :value]
|
||||
parsed.headers.map {|header| header.class} # => [Symbol, Symbol]
|
||||
|
||||
Use class method CSV.generate without option +headers+ to generate to a \String.
|
||||
==== Recipe: Filter Header Strings
|
||||
|
||||
This example uses method CSV#<< to append the rows
|
||||
that are to be generated:
|
||||
output_string = CSV.generate do |csv|
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
output_string # => "Foo,0\nBar,1\nBaz,2\n"
|
||||
Define a custom header converter to modify \String fields.
|
||||
This example defines and uses a custom header converter
|
||||
that capitalizes each header \String:
|
||||
capitalize_converter = proc {|header| header.capitalize }
|
||||
source = "NAME,VALUE\nfoo,0\nbar,1\nbaz,2\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: capitalize_converter)
|
||||
parsed.headers # => ["Name", "Value"]
|
||||
|
||||
==== Generating to a \File
|
||||
==== Recipe: Register Header Converters
|
||||
|
||||
You can generate /CSV data to a \File, with or without headers.
|
||||
Register a custom header converter, assigning it a name;
|
||||
then refer to the converter by its name:
|
||||
capitalize_converter = proc {|header| header.capitalize }
|
||||
CSV::HeaderConverters[:capitalize] = capitalize_converter
|
||||
source = "NAME,VALUE\nfoo,0\nbar,1\nbaz,2\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: :capitalize)
|
||||
parsed.headers # => ["Name", "Value"]
|
||||
|
||||
===== Recipe: Generate to \File with Headers
|
||||
==== Using Multiple Header Converters
|
||||
|
||||
Use class method CSV.open with option +headers+ generate to a \File.
|
||||
You can use multiple header converters in either of these ways:
|
||||
- Specify header converters in option <tt>:header_converters</tt>.
|
||||
- Specify header converters in a custom header converter list.
|
||||
|
||||
This example uses method CSV#<< to append the rows
|
||||
that are to be generated:
|
||||
path = 't.csv'
|
||||
CSV.open(path, 'w', headers: ['Name', 'Value'], write_headers: true) do |csv|
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
|
||||
===== Recipe: Specify Multiple Header Converters in Option :header_converters
|
||||
|
||||
===== Recipe: Generate to \File Without Headers
|
||||
Apply multiple header converters by specifying them in option <tt>:header_conveters</tt>:
|
||||
source = "Name,Value\nfoo,0\nbar,1.0\nbaz,2.0\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: [:downcase, :symbol])
|
||||
parsed.headers # => [:name, :value]
|
||||
|
||||
Use class method CSV.open without option +headers+ to generate to a \File.
|
||||
===== Recipe: Specify Multiple Header Converters in a Custom Header Converter List
|
||||
|
||||
This example uses method CSV#<< to append the rows
|
||||
that are to be generated:
|
||||
path = 't.csv'
|
||||
CSV.open(path, 'w') do |csv|
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
|
||||
|
||||
==== Generating to an \IO Stream
|
||||
|
||||
You can generate \CSV data to an \IO stream, with or without headers.
|
||||
|
||||
==== Recipe: Generate to \IO Stream with Headers
|
||||
|
||||
Use class method CSV.new with option +headers+ to generate \CSV data to an \IO stream:
|
||||
path = 't.csv'
|
||||
File.open(path, 'w') do |file|
|
||||
csv = CSV.new(file, headers: ['Name', 'Value'], write_headers: true)
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
|
||||
|
||||
===== Recipe: Generate to \IO Stream Without Headers
|
||||
|
||||
Use class method CSV.new without option +headers+ to generate \CSV data to an \IO stream:
|
||||
path = 't.csv'
|
||||
File.open(path, 'w') do |file|
|
||||
csv = CSV.new(file)
|
||||
csv << ['Foo', 0]
|
||||
csv << ['Bar', 1]
|
||||
csv << ['Baz', 2]
|
||||
end
|
||||
p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
|
||||
|
||||
=== Filtering: Source and Output Formats
|
||||
|
||||
You can use a Unix-style "filter" for \CSV data.
|
||||
The filter reads source \CSV data and writes output \CSV data as modified by the filter.
|
||||
The input and output \CSV data may be any mixture of \Strings and \IO streams.
|
||||
|
||||
==== Filtering \String to \String
|
||||
|
||||
You can filter one \String to another, with or without headers.
|
||||
|
||||
===== Recipe: Filter \String to \String with Headers
|
||||
|
||||
Use class method CSV.filter with option +headers+ to filter a \String to another \String:
|
||||
in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
out_string = ''
|
||||
CSV.filter(in_string, out_string, headers: true) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
===== Recipe: Filter \String to \String Without Headers
|
||||
|
||||
Use class method CSV.filter without option +headers+ to filter a \String to another \String:
|
||||
in_string = "foo,0\nbar,1\nbaz,2\n"
|
||||
out_string = ''
|
||||
CSV.filter(in_string, out_string) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
==== Filtering \String to \IO Stream
|
||||
|
||||
You can filter a \String to an \IO stream, with or without headers.
|
||||
|
||||
===== Recipe: Filter \String to \IO Stream with Headers
|
||||
|
||||
Use class method CSV.filter with option +headers+ to filter a \String to an \IO stream:
|
||||
in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
path = 't.csv'
|
||||
File.open(path, 'w') do |out_io|
|
||||
CSV.filter(in_string, out_io, headers: true) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
p File.read(path) # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
===== Recipe: Filter \String to \IO Stream Without Headers
|
||||
|
||||
Use class method CSV.filter without option +headers+ to filter a \String to an \IO stream:
|
||||
in_string = "foo,0\nbar,1\nbaz,2\n"
|
||||
path = 't.csv'
|
||||
File.open(path, 'w') do |out_io|
|
||||
CSV.filter(in_string, out_io) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
p File.read(path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
==== Filtering \IO Stream to \String
|
||||
|
||||
You can filter an \IO stream to a \String, with or without headers.
|
||||
|
||||
===== Recipe: Filter \IO Stream to \String with Headers
|
||||
|
||||
Use class method CSV.filter with option +headers+ to filter an \IO stream to a \String:
|
||||
in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
path = 't.csv'
|
||||
File.write(path, in_string)
|
||||
out_string = ''
|
||||
File.open(path, headers: true) do |in_io|
|
||||
CSV.filter(in_io, out_string, headers: true) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
===== Recipe: Filter \IO Stream to \String Without Headers
|
||||
|
||||
Use class method CSV.filter without option +headers+ to filter an \IO stream to a \String:
|
||||
in_string = "foo,0\nbar,1\nbaz,2\n"
|
||||
path = 't.csv'
|
||||
File.write(path, in_string)
|
||||
out_string = ''
|
||||
File.open(path) do |in_io|
|
||||
CSV.filter(in_io, out_string) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
==== Filtering \IO Stream to \IO Stream
|
||||
|
||||
You can filter an \IO stream to another \IO stream, with or without headers.
|
||||
|
||||
===== Recipe: Filter \IO Stream to \IO Stream with Headers
|
||||
|
||||
Use class method CSV.filter with option +headers+ to filter an \IO stream to another \IO stream:
|
||||
in_path = 't.csv'
|
||||
in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
|
||||
File.write(in_path, in_string)
|
||||
out_path = 'u.csv'
|
||||
File.open(in_path) do |in_io|
|
||||
File.open(out_path, 'w') do |out_io|
|
||||
CSV.filter(in_io, out_io, headers: true) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
end
|
||||
p File.read(out_path) # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
|
||||
===== Recipe: Filter \IO Stream to \IO Stream Without Headers
|
||||
|
||||
Use class method CSV.filter without option +headers+ to filter an \IO stream to another \IO stream:
|
||||
in_path = 't.csv'
|
||||
in_string = "foo,0\nbar,1\nbaz,2\n"
|
||||
File.write(in_path, in_string)
|
||||
out_path = 'u.csv'
|
||||
File.open(in_path) do |in_io|
|
||||
File.open(out_path, 'w') do |out_io|
|
||||
CSV.filter(in_io, out_io) do |row|
|
||||
row[0] = row[0].upcase
|
||||
row[1] *= 4
|
||||
end
|
||||
end
|
||||
end
|
||||
p File.read(out_path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
|
||||
Apply multiple header converters by defining and registering a custom header converter list:
|
||||
CSV::HeaderConverters[:my_header_converters] = [:symbol, :downcase]
|
||||
source = "NAME,VALUE\nfoo,0\nbar,1.0\nbaz,2.0\n"
|
||||
parsed = CSV.parse(source, headers: true, header_converters: :my_header_converters)
|
||||
parsed.headers # => [:name, :value]
|
||||
|
|
@ -0,0 +1,6 @@
|
|||
== Recipes for \CSV
|
||||
|
||||
See:
|
||||
- {Recipes for Parsing CSV}[./parsing_rdoc.html]
|
||||
- {Recipes for Generating CSV}[./generating_rdoc.html]
|
||||
- {Recipes for Filtering CSV}[./filtering_rdoc.html]
|
||||
|
|
@ -43,8 +43,15 @@ Gem::Specification.new do |spec|
|
|||
"LICENSE.txt",
|
||||
"NEWS.md",
|
||||
"README.md",
|
||||
"doc/csv/recipes.rdoc"
|
||||
]
|
||||
recipes_dir = File.join(doc_dir, "csv", "recipes")
|
||||
if File.exist?(recipes_dir)
|
||||
Dir.chdir(recipes_dir) do
|
||||
Dir.glob("**/*.rdoc").each do |recipe_file|
|
||||
rdoc_files << "doc/csv/recipes/#{recipe_file}"
|
||||
end
|
||||
end
|
||||
end
|
||||
spec.extra_rdoc_files = rdoc_files
|
||||
|
||||
spec.required_ruby_version = ">= 2.5.0"
|
||||
|
|
|
|||
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