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[ruby/csv] Emphasize with-headers over without-headers in recipes (#180)
c7bbedd28aThis commit is contained in:
Burdette Lamar
Sutou Kouhei
parent
76e5e5aaec
commit
4641a9a92b
Notes:
git
2020-11-24 09:34:29 +09:00
1 changed files with 110 additions and 110 deletions
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@ -7,14 +7,14 @@ All code snippets on this page assume that the following has been executed:
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- {Parsing: Source Formats}[#label-Parsing-3A+Source+Formats]
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- {Parse from String}[#label-Parse+from+String]
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- {Parse from String Without Headers}[#label-Parse+from+String+Without+Headers]
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- {Parse from String with Headers}[#label-Parse+from+String+with+Headers]
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- {Parse from String Without Headers}[#label-Parse+from+String+Without+Headers]
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- {Parse from File}[#label-Parse+from+File]
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- {Parse from File Without Headers}[#label-Parse+from+File+Without+Headers]
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- {Parse from File with Headers}[#label-Parse+from+File+with+Headers]
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- {Parse from File Without Headers}[#label-Parse+from+File+Without+Headers]
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- {Parse from IO Stream}[#label-Parse+from+IO+Stream]
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- {Parse from IO Stream Without Headers}[#label-Parse+from+IO+Stream+Without+Headers]
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- {Parse from IO Stream with Headers}[#label-Parse+from+IO+Stream+with+Headers]
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- {Parse from IO Stream Without Headers}[#label-Parse+from+IO+Stream+Without+Headers]
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- {Parsing: Field Converters}[#label-Parsing-3A+Field+Converters]
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- {Convert Fields to Objects}[#label-Convert+Fields+to+Objects]
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- {Convert Fields to Objects Using Built-In Converters}[#label-Convert+Fields+to+Objects+Using+Built-In+Converters]
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@ -22,48 +22,32 @@ All code snippets on this page assume that the following has been executed:
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- {Filter Field Strings}[#label-Filter+Field+Strings]
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- {Generating: Output Formats}[#label-Generating-3A+Output+Formats]
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- {Generate to String}[#label-Generate+to+String]
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- {Generate to String Without Headers}[#label-Generate+to+String+Without+Headers]
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- {Generate to String with Headers}[#label-Generate+to+String+with+Headers]
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- {Generate to String Without Headers}[#label-Generate+to+String+Without+Headers]
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- {Generate to File}[#label-Generate+to+File]
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- {Generate to File Without Headers}[#label-Generate+to+File+Without+Headers]
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- {Generate to File with Headers}[#label-Generate+to+File+with+Headers]
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- {Generate to File Without Headers}[#label-Generate+to+File+Without+Headers]
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- {Generate to IO Stream}[#label-Generate+to+IO+Stream]
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- {Generate to IO Stream Without Headers}[#label-Generate+to+IO+Stream+Without+Headers]
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- {Generate to IO Stream with Headers}[#label-Generate+to+IO+Stream+with+Headers]
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- {Generate to IO Stream Without Headers}[#label-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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- {Filter String to String}[#label-Filter+String+to+String]
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- {Filter String to String Without Headers}[#label-Filter+String+to+String+Without+Headers]
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- {Filter String to String with Headers}[#label-Filter+String+to+String+with+Headers]
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- {Filter String to String Without Headers}[#label-Filter+String+to+String+Without+Headers]
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- {Filter String to IO Stream}[#label-Filter+String+to+IO+Stream]
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- {Filter String to IO Stream Without Headers}[#label-Filter+String+to+IO+Stream+Without+Headers]
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- {Filter String to IO Stream with Headers}[#label-Filter+String+to+IO+Stream+with+Headers]
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- {Filter String to IO Stream Without Headers}[#label-Filter+String+to+IO+Stream+Without+Headers]
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- {Filter IO Stream to String}[#label-Filter+IO+Stream+to+String]
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- {Filter IO Stream to String Without Headers}[#label-Filter+IO+Stream+to+String+Without+Headers]
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- {Filter IO Stream to String with Headers}[#label-Filter+IO+Stream+to+String+with+Headers]
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- {Filter IO Stream to String Without Headers}[#label-Filter+IO+Stream+to+String+Without+Headers]
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- {Filter IO Stream to IO Stream}[#label-Filter+IO+Stream+to+IO+Stream]
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- {Filter IO Stream to IO Stream Without Headers}[#label-Filter+IO+Stream+to+IO+Stream+Without+Headers]
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- {Filter IO Stream to IO Stream with Headers}[#label-Filter+IO+Stream+to+IO+Stream+with+Headers]
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- {Filter IO Stream to IO Stream Without Headers}[#label-Filter+IO+Stream+to+IO+Stream+Without+Headers]
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=== Parsing: Source Formats
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==== Parse from \String
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===== Parse from \String Without Headers
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\Class method CSV.parse can read a source \String all at once,
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and so may have memory resource implications:
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string = "foo,0\nbar,1\nbaz,2\n"
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CSV.parse(string) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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Instance method CSV#each can read a source \String one row at a time:
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CSV.new(string).each do |row|
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p row
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end
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Output:
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["foo", "0"]
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["bar", "1"]
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["baz", "2"]
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===== Parse from \String with Headers
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\Class method CSV.parse can read a source \String all at once,
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@ -80,18 +64,15 @@ Ouput:
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#<CSV::Row "Name":"bar" "Value":"1">
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#<CSV::Row "Name":"baz" "Value":"2">
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==== Parse from \File
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===== Parse from \String Without Headers
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===== Parse from \File Without Headers
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\Class method CSV.read can read a file all at once:
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\Class method CSV.parse can read a source \String all at once,
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and so may have memory resource implications:
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string = "foo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.write(path, string)
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CSV.read(path) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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CSV.parse(string) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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\Class method CSV.foreach can read one row at a time:
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CSV.foreach(path) do |row|
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Instance method CSV#each can read a source \String one row at a time:
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CSV.new(string).each do |row|
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p row
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end
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Output:
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@ -99,6 +80,8 @@ Output:
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["bar", "1"]
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["baz", "2"]
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==== Parse from \File
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===== Parse from \File with Headers
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Instance method CSV#read can reada file all at once:
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@ -116,29 +99,25 @@ Output:
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#<CSV::Row "Name":"bar" "Value":"1">
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#<CSV::Row "Name":"baz" "Value":"2">
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==== Parse from \IO Stream
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===== Parse from \File Without Headers
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===== Parse from \IO Stream Without Headers
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\Class method CSV.parse can read an \IO stream all at once:
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\Class method CSV.read can read a file all at once:
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string = "foo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.write(path, string)
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File.open(path) do |file|
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CSV.parse(file)
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end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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CSV.read(path) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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\Class method CSV.foreach can read one row at a time:
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File.open(path) do |file|
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CSV.foreach(file) do |row|
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p row
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end
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CSV.foreach(path) do |row|
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p row
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end
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Output:
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["foo", "0"]
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["bar", "1"]
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["baz", "2"]
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==== Parse from \IO Stream
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===== Parse from \IO Stream with Headers
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\Class method CSV.parse can read an \IO stream all at once:
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@ -160,6 +139,27 @@ Output:
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#<CSV::Row "Name":"bar" "Value":"1">
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#<CSV::Row "Name":"baz" "Value":"2">
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===== Parse from \IO Stream Without Headers
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\Class method CSV.parse can read an \IO stream all at once:
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string = "foo,0\nbar,1\nbaz,2\n"
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path = 't.csv'
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File.write(path, string)
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File.open(path) do |file|
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CSV.parse(file)
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end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
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\Class method CSV.foreach can read one row at a time:
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File.open(path) do |file|
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CSV.foreach(file) do |row|
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p row
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end
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end
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Output:
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["foo", "0"]
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["bar", "1"]
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["baz", "2"]
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=== Parsing: Field Converters
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==== Convert Fields to Objects
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@ -235,19 +235,6 @@ You can also register a custom field converter, then refer to it by name:
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=== Generating: Output Formats
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==== Generate to \String Without Headers
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\Class method CSV.generate can 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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==== Generate to \String
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===== Generate to \String with Headers
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@ -263,19 +250,18 @@ that are to be generated:
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end
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output_string # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
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===== Generate to \File Without Headers
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===== Generate to \String Without Headers
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\Class method CSV.open can generate to a \File.
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\Class method CSV.generate can 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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path = 't.csv'
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CSV.open(path, 'w') do |csv|
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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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p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
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output_string # => "Foo,0\nBar,1\nBaz,2\n"
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==== Generate to \File
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@ -293,20 +279,22 @@ that are to be generated:
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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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==== Generate to \IO Stream
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===== Generate to \File Without Headers
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===== Generate to \IO Stream Without Headers
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\Class method CSV.open can generate to a \File.
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\Class method CSV.new can generate \CSV data to an \IO stream:
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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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File.open(path, 'w') do |file|
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csv = CSV.new(file)
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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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==== Generate to \IO Stream
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==== Generate to \IO Stream with Headers
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\\Classs method CSV.new can generate \CSV data to an \IO stream:
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@ -319,6 +307,18 @@ that are to be generated:
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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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===== Generate to \IO Stream Without Headers
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\Class method CSV.new can 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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=== Filtering: Source and Output Formats
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\Class method CSV.filter provides a Unix-style filter for \CSV data.
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@ -326,16 +326,6 @@ The source \CSV data is processed to form output \CSV data.
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==== Filter \String to \String
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===== Filter \String to \String Without Headers
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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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===== Filter \String to \String with Headers
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in_string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
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@ -346,19 +336,17 @@ The source \CSV data is processed to form output \CSV data.
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end
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out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filter \String to \IO Stream
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===== Filter \String to \IO Stream Without Headers
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===== Filter \String to \String Without Headers
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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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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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p File.read(path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filter \String to \IO Stream
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===== Filter \String to \IO Stream with Headers
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@ -372,21 +360,19 @@ The source \CSV data is processed to form output \CSV data.
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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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==== Filter \IO Stream to \String
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===== Filter \IO Stream to \String Without Headers
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===== Filter \String to \IO Stream Without Headers
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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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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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out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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p File.read(path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filter \IO Stream to \String
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===== Filter \IO Stream to \String with Headers
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@ -402,23 +388,21 @@ The source \CSV data is processed to form output \CSV data.
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end
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out_string # => "Name,Value\nFOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filter \IO Stream to \IO Stream
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===== Filter \IO Stream to \String Without Headers
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===== Filter \IO Stream to \IO Stream Without Headers
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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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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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p File.read(out_path) # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
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==== Filter \IO Stream to \IO Stream
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===== Filter \IO Stream to \IO Stream with Headers
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@ -435,3 +419,19 @@ The source \CSV data is processed to form output \CSV data.
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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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===== Filter \IO Stream to \IO Stream Without Headers
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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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