End of Life Ruby 3.0 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

class method

CSV.filter

filter(**options) {|row| ... }

filter(in_string, **options) {|row| ... }

filter(in_io, **options) {|row| ... }

filter(in_string, out_string, **options) {|row| ... }

filter(in_string, out_io, **options) {|row| ... }

filter(in_io, out_string, **options) {|row| ... }

filter(in_io, out_io, **options) {|row| ... }

lib/csv.rb View on GitHub ↗

# File tmp/rubies/ruby-3.0.5/lib/csv.rb, line 1052
def filter(input=nil, output=nil, **options)
  # parse options for input, output, or both
  in_options, out_options = Hash.new, {row_sep: $INPUT_RECORD_SEPARATOR}
  options.each do |key, value|
    case key.to_s
    when /\Ain(?:put)?_(.+)\Z/
      in_options[$1.to_sym] = value
    when /\Aout(?:put)?_(.+)\Z/
      out_options[$1.to_sym] = value
    else
      in_options[key]  = value
      out_options[key] = value
    end
  end

  # build input and output wrappers
  input  = new(input  || ARGF, **in_options)
  output = new(output || $stdout, **out_options)

  # process headers
  need_manual_header_output =
    (in_options[:headers] and
     out_options[:headers] == true and
     out_options[:write_headers])
  if need_manual_header_output
    first_row = input.shift
    if first_row
      if first_row.is_a?(Row)
        headers = first_row.headers
        yield headers
        output << headers
      end
      yield first_row
      output << first_row
    end
  end

  # read, yield, write
  input.each do |row|
    yield row
    output << row
  end
end

Reads CSV input and writes CSV output.

For each input row:

Forms the data into:
- A CSV::Row object, if headers are in use.
- An Array of Arrays, otherwise.
Calls the block with that object.
Appends the block’s return value to the output.

Arguments:

CSV source:
- Argument in_string, if given, should be a String object; it will be put into a new StringIO object positioned at the beginning.
- Argument in_io, if given, should be an IO object that is open for reading; on return, the IO object will be closed.
- If neither in_string nor in_io is given, the input stream defaults to ARGF.
CSV output:
- Argument out_string, if given, should be a String object; it will be put into a new StringIO object positioned at the beginning.
- Argument out_io, if given, should be an IO object that is ppen for writing; on return, the IO object will be closed.
- If neither out_string nor out_io is given, the output stream defaults to $stdout.
Argument options should be keyword arguments.
- Each argument name that is prefixed with in_ or input_ is stripped of its prefix and is treated as an option for parsing the input. Option input_row_sep defaults to $INPUT_RECORD_SEPARATOR.
- Each argument name that is prefixed with out_ or output_ is stripped of its prefix and is treated as an option for generating the output. Option output_row_sep defaults to $INPUT_RECORD_SEPARATOR.
- Each argument not prefixed as above is treated as an option both for parsing the input and for generating the output.
- See Options for Parsing and Options for Generating.

Example:

Example

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"

See also .foreach .generate also in 3.3 · 3.2 · 3.1

next ›.foreach