From: dblack@...
Date: 2007-06-06T20:08:30+09:00
Subject: Re: efficient regex scanning

Hi --

On Wed, 6 Jun 2007, Trochalakis Christos wrote:

> Hello there,
>
> I wan't to extract all the words from a file and so i wrote the
> following code:
>
> file = ARGV[0]
> File.open('output','w') {|f|
>        IO.read(file).scan(/\w+/).each{|w| f.print w}
> }
>
> The problem with this code is that it stores all the words in an array
> which is not so good in terms of efficiency.
> Is there a better way to do it?
> Something like IO.read(file).each_scan { foo }

You could do something like this (untested, and reversing your logic
somewhat):

   File.open(file).each {|line| f.print(line.scan(/\w+/)) }

(You might want to join them with a space or something so they don't
all run together.)


David

-- 
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