From: James Gray <james@...>
Date: 2008-01-11T00:12:01+09:00
Subject: Re: Multiline (block) CSV file processing

On Jan 10, 2008, at 7:47 AM, Phil Rhoades wrote:

> I am looking for suggestions for Ruby utilities (and gems?) for a
> flexible, easy method of processing multi-line blocks of CSV text eg  
> in
> a CSV file, lines 1-5 are the first block and lines 6-10 are the  
> second
> block etc.  Then for each block I want to:
>
> - print the first field of line 1
> - second field of line 2
> - fifth field of line 3
> - tenth field of line 4
> - twelfth field of line 5
>
> as fields of a new line.

Well, if I fully understand the request, I would use code like the  
following with the fastercsv gem:

#!/usr/bin/env ruby -wKU

require "rubygems"
require "faster_csv"

input  = FCSV.open(ARGV.shift)
output = FCSV.open("filtered.csv", "w")

catch(:out_of_lines) do
   loop do
     lines  =  Array.new(5) { input.shift or throw :out_of_lines }
     output << lines.zip([0, 1, 4, 9, 11]).map { |line, i| line[i] }
   end
end

__END__

Hope that helps.

James Edward Gray II