From: Thomas Worm <usenet@...4r.de>
Date: 2007-07-19T20:55:01+09:00
Subject: Re: identify and extract positions from a string - how to?

On Thu, 19 Jul 2007 20:16:12 +0900, Marc Hoeppner wrote:

> As it is now I have a file that contains coordinates and a second file
> that contains the string that I want to extract from.
> 
> So ideally the script would read each line of the coordinate file
> 
> 45..78
> 90..120
> etc

Those ..-things are called ranges, which, what wonder, are a class in 
ruby. Have a look at http://corelib.rubyonrails.org/ for the class Range.

another way to express str[45..78] is str[45,78] or str.slice(45,78) or 
str.slice(45..78), where the numbers can be replaced by variables:
str[fr..to], str[fr,to], str.slice[fr,to], str.slice(fr..to)

This information can be found at the same webpage, just look for the 
class String ;-)

 
> and uses it in the extraction method
> 
> file.readlines each do |l|
>   puts string[l]
> end
> 
> Doesnt work tho -any suggestions on how to pipe each line of the
> coordinate file to the string method? I know I know, probably simple,
> but I am still learning ;)

l is a String-object, not a Range-object.

file.readlines each do |l|
  fr, to = l.split(/\.\./)
  puts string[fr,to]
end

should do the job.

The thingy with the slashes in the split-method is a regular expression.

Regards
Thomas