From: Robert Klemme <shortcutter@...>
Date: 2006-05-26T19:34:33+09:00
Subject: Re: Regexp to esclude substrings

2006/5/25, vincent <dontspam@dontspam.com>:
> I'm trying to resolve a very simple problem, but I'm encountering some
> issues.
>
> Input: "this is a string where you can find some words"
> Output: [this, string, where, can, find, some, words]

irb(main):001:0> "this is a string where you can find some
words".scan(/\w+/).reject {|w| case w; when "is", "a", "you"
 then true else false end }
=> ["this", "string", "where", "can", "find", "some", "words"]

> So I'm trying to eliminate ' is ', ' a ' and ' you ' from the string
> (note the spaces, 'this' shouldn't be eliminated just because it
> includes 'is').
>
> I tried the following (and many others), but it doens't work:
> my_string = input_string.gsub!(/\s+(is|a|you)\s+/i,' ').split

Anchoring at word boundaries helps:

irb(main):006:0> "this is a string where you can find some
words".gsub(/\b(is|a|you)\s+/, ' ').split /\s+/
=> ["this", "string", "where", "can", "find", "some", "words"]

This one is probably a bit more efficient

irb(main):011:0> require 'enumerator'
=> true
irb(main):012:0> "this is a string where you can find some
words".to_enum(:scan, /\w+/).select {|w| /^(is|a|you)$/ !~ w
}
=> ["this", "string", "where", "can", "find", "some", "words"]

There's a multitude of other solutions as the number of answers indicates. :-)

Kind regards

robert

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