From: Erik Veenstra <erikveen@...>
Date: 2007-02-08T03:27:04+09:00
Subject: Re: Parse csv similar file

Nice abstraction... ;]

(By heart: This group_by is part of one of the Rails packages.)

gegroet,
Erik V. - http://www.erikveen.dds.nl/

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 module Enumerable
   def hash_by(&block)
     inject({}){|h, o| (h[block[o]] ||= []) << o ; h}
   end

   def group_by(&block)
     #hash_by(&block).values
     hash_by(&block).sort.transpose.pop
   end
 end

 hash =
 File.open("input.txt") do |f|
   f.readlines.group_by do |line|
     line.scan(/;(E\d+);/)
   end.collect do |group|
     group.collect do |string|
       string.scan(/;E\d+;(.*)/).flatten.shift
     end.join(",")
   end
 end

 p hash

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