From: Brian Adkins <lojicdotcom@...>
Date: 2008-01-11T04:19:57+09:00
Subject: Re: Multiline (block) CSV file processing

On Jan 10, 1:40 pm, Brian Adkins <lojicdot...@gmail.com> wrote:
> On Jan 10, 11:18 am, Phil Rhoades <p...@pricom.com.au> wrote:
>
> > Thanks but not quite - say my input file is:
>
> > 1 2 3 4 5 6 7 8 9 a b c
> > 11 12 13 14 15 16 17 18 19 d e f
> > 21 22 23 24 25 26 27 28 29 g h i
> > 31 32 33 34 35 36 37 38 39 j k l
> > 41 42 43 44 45 46 47 48 49 m n o
>
> > The output should be:
>
> > 1 12 25 j o

This is a little more general.

def block_extractor file, fields,
    splitter = lambda {|line| line.split }
  while !file.eof
    result = []
    fields.each do |field|
      line = file.readline
      result << splitter.call(line.chomp)[field-1] if field
    end
    yield result
  end
end

File.open("data.txt", "r") do |file|
  block_extractor(file, [1,2,5,10,12]) do |fields|
    puts fields.join(' ')
  end
end