diff options
author | Burdette Lamar <BurdetteLamar@Yahoo.com> | 2020-09-17 16:52:44 -0500 |
---|---|---|
committer | Sutou Kouhei <kou@cozmixng.org> | 2020-11-24 09:33:55 +0900 |
commit | 8ea293b79c63d76443dd1fb352818c133302584d (patch) | |
tree | adea92db2bc63873c9906a13e796feb0c2aeaa9c /doc | |
parent | 614afb1647d9c9eb170262c8b033f000c5beb6f0 (diff) |
[ruby/csv] Experimenting with recipes in CSV RDoc (#175)
https://github.com/ruby/csv/commit/01ffd0d2de
Notes
Notes:
Merged: https://github.com/ruby/ruby/pull/3804
Diffstat (limited to 'doc')
-rw-r--r-- | doc/csv/recipes.rdoc | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/doc/csv/recipes.rdoc b/doc/csv/recipes.rdoc new file mode 100644 index 0000000000..eda18f6359 --- /dev/null +++ b/doc/csv/recipes.rdoc @@ -0,0 +1,325 @@ +== Recipes + +=== Contents +- {Parsing}[#label-Parsing] + - {Parse from String Without Headers}[#label-Parse+from+String+Without+Headers] + - {Parse from String with Headers}[#label-Parse+from+String+with+Headers] + - {Parse from File Without Headers}[#label-Parse+from+File+Without+Headers] + - {Parse from File with Headers}[#label-Parse+from+File+with+Headers] + - {Parse from IO Stream Without Headers}[#label-Parse+from+IO+Stream+Without+Headers] + - {Parse from IO Stream with Headers}[#label-Parse+from+IO+Stream+with+Headers] +- {Generating}[#label-Generating] + - {Generate to String Without Headers}[#label-Generate+to+String+Without+Headers] + - {Generate to String with Headers}[#label-Generate+to+String+with+Headers] + - {Generate to File Without Headers}[#label-Generate+to+File+Without+Headers] + - {Generate to File with Headers}[#label-Generate+to+File+with+Headers] + - {Generate to IO Stream Without Headers}[#label-Generate+to+IO+Stream+Without+Headers] + - {Generate to IO Stream with Headers}[#label-Generate+to+IO+Stream+with+Headers] +- {Filtering}[#label-Filtering] + - {Filter String to String Without Headers}[#label-Filter+String+to+String+Without+Headers] + - {Filter String to String with Headers}[#label-Filter+String+to+String+with+Headers] + - {Filter String to IO Stream Without Headers}[#label-Filter+String+to+IO+Stream+Without+Headers] + - {Filter String to IO Stream with Headers}[#label-Filter+String+to+IO+Stream+with+Headers] + - {Filter IO Stream to String Without Headers}[#label-Filter+IO+Stream+to+String+Without+Headers] + - {Filter IO Stream to String with Headers}[#label-Filter+IO+Stream+to+String+with+Headers] + - {Filter IO Stream to IO Stream Without Headers}[#label-Filter+IO+Stream+to+IO+Stream+Without+Headers] + - {Filter IO Stream to IO Stream with Headers}[#label-Filter+IO+Stream+to+IO+Stream+with+Headers] + +=== Parsing + +==== Parse from \String Without Headers + +\Class method CSV.parse can read a source \String all at once, +and so may have memory resource implications: + string = "foo,0\nbar,1\nbaz,2\n" + CSV.parse(string) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]] + +Instance method CSV#each can read a source \String one row at a time: + CSV.new(string).each do |row| + p row + end +Output: + ["foo", "0"] + ["bar", "1"] + ["baz", "2"] + +==== Parse from \String with Headers + +\Class method CSV.parse can read a source \String all at once, +and so may have memory resource implications: + string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + CSV.parse(string, headers: true) # => #<CSV::Table mode:col_or_row row_count:4> + +Instance method CSV#each can read a source \String one row at a time: + CSV.new(string, headers: true).each do |row| + p row + end +Ouput: + #<CSV::Row "Name":"foo" "Value":"0"> + #<CSV::Row "Name":"bar" "Value":"1"> + #<CSV::Row "Name":"baz" "Value":"2"> + +==== Parse from \File Without Headers + +\Class method CSV.read can read a file all at once: + string = "foo,0\nbar,1\nbaz,2\n" + path = 't.csv' + File.write(path, string) + CSV.read(path) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]] + +\Class method CSV.foreach can read one row at a time: + CSV.foreach(path) do |row| + p row + end +Output: + ["foo", "0"] + ["bar", "1"] + ["baz", "2"] + +==== Parse from \File with Headers + +Instance method CSV#read can reada file all at once: + string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + path = 't.csv' + File.write(path, string) + CSV.read(path, headers: true) # => #<CSV::Table mode:col_or_row row_count:4> + +\Class method CSV.foreach can read one row at a time: + CSV.foreach(path, headers: true) do |row| + p row + end +Output: + #<CSV::Row "Name":"foo" "Value":"0"> + #<CSV::Row "Name":"bar" "Value":"1"> + #<CSV::Row "Name":"baz" "Value":"2"> + +==== Parse from \IO Stream Without Headers + +\Class method CSV.parse can read an \IO stream all at once: + string = "foo,0\nbar,1\nbaz,2\n" + path = 't.csv' + File.write(path, string) + File.open(path) do |file| + CSV.parse(file) + end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]] + +\Class method CSV.foreach can read one row at a time: + File.open(path) do |file| + CSV.foreach(file) do |row| + p row + end + end +Output: + ["foo", "0"] + ["bar", "1"] + ["baz", "2"] + +==== Parse from \IO Stream with Headers + +\Class method CSV.parse can read an \IO stream all at once: + string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" + path = 't.csv' + File.write(path, string) + File.open(path) do |file| + CSV.parse(file, headers: true) + end # => #<CSV::Table mode:col_or_row row_count:4> + +\Class method CSV.foreach can read one row at a time: + File.open(path) do |file| + CSV.foreach(file, headers: true) do |row| + p row + end + end +Output: + #<CSV::Row "Name":"foo" "Value":"0"> + #<CSV::Row "Name":"bar" "Value":"1"> + #<CSV::Row "Name":"baz" "Value":"2"> + +=== Generating + +==== Generate to \String Without Headers + +\Class method CSV.generate can generate to a \String. + +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" + +==== Generate to \String with Headers + +\Class method CSV.generate can generate to a \String. + +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" + +==== Generate to \File Without Headers + +\Class method CSV.open can generate to a \File. + +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" + +==== Generate to \File with Headers + +\Class method CSV.open can generate to a \File. + +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" + +==== Generate to \IO Stream Without Headers + +\Class method CSV.new can 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" + +==== Generate to \IO Stream with Headers + +\\Classs method CSV.new can 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" + +=== Filtering + +\Class method CSV.filter provides a Unix-style filter for \CSV data. +The input \CSV data is processed to form output \CSV data. + +==== Filter \String to \String Without Headers + + 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" + +==== Filter \String to \String with Headers + + 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" + +==== Filter \String to \IO Stream Without Headers + + 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" + +==== Filter \String to \IO Stream with Headers + + 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" + +==== Filter \IO Stream to \String Without Headers + + 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" + +==== Filter \IO Stream to \String with Headers + + 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" + +==== Filter \IO Stream to \IO Stream Without Headers + + 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" + +==== Filter \IO Stream to \IO Stream with Headers + + 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" |