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author | Burdette Lamar <BurdetteLamar@Yahoo.com> | 2020-10-05 18:53:10 -0500 |
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committer | Sutou Kouhei <kou@cozmixng.org> | 2020-11-24 09:33:55 +0900 |
commit | 6e28ec06c15acd5427629873b9d129c37ecadd51 (patch) | |
tree | 3d4e0b07638afb40afe73574c7b9cad982e1a5f5 | |
parent | 4641a9a92b449e2e9d4cbc91a93de27f98396a96 (diff) | |
download | ruby-6e28ec06c15acd5427629873b9d129c37ecadd51.tar.gz |
[ruby/csv] RDoc recipes: add introductory texts to code recipes (#181)
https://github.com/ruby/csv/commit/c52d53761e
-rw-r--r-- | doc/csv/recipes.rdoc | 84 |
1 files changed, 61 insertions, 23 deletions
diff --git a/doc/csv/recipes.rdoc b/doc/csv/recipes.rdoc index 816f9337b6..c4be14aa1d 100644 --- a/doc/csv/recipes.rdoc +++ b/doc/csv/recipes.rdoc @@ -46,16 +46,20 @@ All code snippets on this page assume that the following has been executed: === Parsing: Source Formats +You can parse \CSV data from a \String, from a \File (via its path), or from an \IO stream. + ==== Parse from \String +You can parse \CSV data from a \String, with or without headers. + ===== Parse from \String with Headers -\Class method CSV.parse can read a source \String all at once, -and so may have memory resource implications: +Use class method CSV.parse with option +headers+ to read a source \String all at once +(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: +Use instance method CSV#each with option +headers+ to read a source \String one row at a time: CSV.new(string, headers: true).each do |row| p row end @@ -66,12 +70,12 @@ Ouput: ===== Parse from \String Without Headers -\Class method CSV.parse can read a source \String all at once, -and so may have memory resource implications: +Use class method CSV.parse without option +headers+ to read a source \String all at once +(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: +Use instance method CSV#each without option +headers+ to read a source \String one row at a time: CSV.new(string).each do |row| p row end @@ -82,15 +86,17 @@ Output: ==== Parse from \File +You can parse \CSV data from a \File, with or without headers. + ===== Parse from \File with Headers -Instance method CSV#read can reada file all at once: +Use instance method CSV#read with option +headers+ to read a 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: +Use class method CSV.foreach with option +headers+ to read one row at a time: CSV.foreach(path, headers: true) do |row| p row end @@ -101,13 +107,13 @@ Output: ===== Parse from \File Without Headers -\Class method CSV.read can read a file all at once: +Use class method CSV.read without option +headers+ to 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: +Use class method CSV.foreach without option +headers+ to read one row at a time: CSV.foreach(path) do |row| p row end @@ -118,9 +124,11 @@ Output: ==== Parse from \IO Stream +You can parse \CSV data from an \IO stream, with or without headers. + ===== Parse from \IO Stream with Headers -\Class method CSV.parse can read an \IO stream all at once: +Use class method CSV.parse with option +headers+ to read an \IO stream all at once: string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n" path = 't.csv' File.write(path, string) @@ -128,7 +136,7 @@ Output: 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: +Use class method CSV.foreach with option +headers+ to read one row at a time: File.open(path) do |file| CSV.foreach(file, headers: true) do |row| p row @@ -141,7 +149,7 @@ Output: ===== Parse from \IO Stream Without Headers -\Class method CSV.parse can read an \IO stream all at once: +Use class method CSV.parse without option +headers+ to read an \IO stream all at once: string = "foo,0\nbar,1\nbaz,2\n" path = 't.csv' File.write(path, string) @@ -149,7 +157,7 @@ Output: CSV.parse(file) end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]] -\Class method CSV.foreach can read one row at a time: +Use class method CSV.foreach without option +headers+ to read one row at a time: File.open(path) do |file| CSV.foreach(file) do |row| p row @@ -162,9 +170,12 @@ Output: === Parsing: Field Converters +You can use field converters to change parsed Strings into other objects, +or to otherwise modify \String fields. + ==== Convert Fields to Objects -Use field converters to change parsed Strings into other, more specific, object. +Use field converters to change parsed Strings into other, more specific, objects. ==== Convert Fields to Objects Using Built-In Converters @@ -189,6 +200,7 @@ Output: ==== Convert Fields to Objects Using Custom Converters +You can define custom field converters to convert \String fields into other objects. This example defines and uses a custom field converter that converts each column-1 value to a \Rational object. @@ -213,6 +225,7 @@ You can also register a custom field converter, then refer to it by name: ==== Filter Field Strings +You can define custom field converters to modify \String fields. This example defines and uses a custom field converter that strips whitespace from each field value. @@ -235,11 +248,15 @@ You can also register a custom field converter, then refer to it by name: === Generating: Output Formats +You can generate \CSV output to a \String, to a \File (via its path), or to an \IO stream. + ==== Generate to \String +You can generate \CSV output to a \String, with or without headers. + ===== Generate to \String with Headers -\Class method CSV.generate can generate to a \String. +Use class method CSV.generate with option +headers+ to generate to a \String. This example uses method CSV#<< to append the rows that are to be generated: @@ -252,7 +269,7 @@ that are to be generated: ===== Generate to \String Without Headers -\Class method CSV.generate can generate to a \String. +Use class method CSV.generate without option +headers+ to generate to a \String. This example uses method CSV#<< to append the rows that are to be generated: @@ -265,9 +282,11 @@ that are to be generated: ==== Generate to \File +You can generate /CSV data to a \File, with or without headers. + ===== Generate to \File with Headers -\Class method CSV.open can generate to a \File. +Use class method CSV.open with option +headers+ generate to a \File. This example uses method CSV#<< to append the rows that are to be generated: @@ -281,7 +300,7 @@ that are to be generated: ===== Generate to \File Without Headers -\Class method CSV.open can generate to a \File. +Use class method CSV.open without option +headers+ to generate to a \File. This example uses method CSV#<< to append the rows that are to be generated: @@ -295,9 +314,11 @@ that are to be generated: ==== Generate to \IO Stream +You can generate \CSV data to an \IO stream, with or without headers. + ==== Generate to \IO Stream with Headers -\\Classs method CSV.new can generate \CSV data to an \IO stream: +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) @@ -309,7 +330,7 @@ that are to be generated: ===== Generate to \IO Stream Without Headers -\Class method CSV.new can generate \CSV data to an \IO stream: +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) @@ -321,13 +342,17 @@ that are to be generated: === Filtering: Source and Output Formats -\Class method CSV.filter provides a Unix-style filter for \CSV data. -The source \CSV data is processed to form output \CSV data. +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. ==== Filter \String to \String +You can filter one \String to another, with or without headers. + ===== 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| @@ -338,6 +363,7 @@ The source \CSV data is processed to form output \CSV data. ===== 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| @@ -348,8 +374,11 @@ The source \CSV data is processed to form output \CSV data. ==== Filter \String to \IO Stream +You can filter a \String to an \IO stream, with or without headers. + ===== 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| @@ -362,6 +391,7 @@ The source \CSV data is processed to form output \CSV data. ===== 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| @@ -374,8 +404,11 @@ The source \CSV data is processed to form output \CSV data. ==== Filter \IO Stream to \String +You can filter an \IO stream to a \String, with or without headers. + ===== 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) @@ -390,6 +423,7 @@ The source \CSV data is processed to form output \CSV data. ===== 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) @@ -404,8 +438,11 @@ The source \CSV data is processed to form output \CSV data. ==== Filter \IO Stream to \IO Stream +You can filter an \IO stream to another \IO stream, with or without headers. + ===== 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) @@ -422,6 +459,7 @@ The source \CSV data is processed to form output \CSV data. ===== 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) |