From: Phil Rhoades <phil@...>
Date: 2008-01-11T07:21:05+09:00
Subject: Re: Multiline (block) CSV file processing

Brian,


On Fri, 2008-01-11 at 06:47 +0900, Phil Rhoades wrote:
> Brian,
> 
> 
> On Fri, 2008-01-11 at 04:19 +0900, Brian Adkins wrote:
> > 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
> 
> 
> Thanks! - now I just need to work out how that actually works and then
> work out how I can modify it to use command line parameters.


I apologise for replying to my own post but I have had a look at this
and read up about Procs and Lambdas and I can sorta see what you are
doing but would you be so kind as to elaborate on the code a bit? - I
think other people would find it useful as well . .

Also, to generalise the code further, how would you select two of more
fields from each line?

Thanks,

Phil.
-- 
Philip Rhoades

Pricom Pty Limited  (ACN 003 252 275  ABN 91 003 252 275)
GPO Box 3411
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Australia
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E-mail:  phil@pricom.com.au