From: Gennady <gfb@...>
Date: 2003-03-12T09:48:59+09:00
Subject: Re: a newbie question


----- Original Message -----
From: "Daniel Carrera" <dcarrera@math.umd.edu>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Tuesday, March 11, 2003 3:56 PM
Subject: Re: a newbie question


> Use Array#grep

That's what I've been missing in Ruby!!! Thank you very much, Daniel (and
Matz, of course). I just verified that Enumerable#grep simply invokes method
"===" on its parameter for every element, and that's exactly what I usually
need. And with an optional block you get "selective collect" functionality.
This is so great!!!

Gennady.

>
> >> %w{ cat dog mouse zebra rhino }
> => ["cat", "dog", "mouse", "zebra", "rhino"]
> >> %w{ cat dog mouse zebra rhino }.grep(/e/)
> => ["mouse", "zebra"]
>
> On Wed, Mar 12, 2003 at 08:51:13AM +0900, Ben Thomas wrote:
> > Hi,
> >
> > I am trying to create an array from another array using a regular
> > expression to compare them. If an element match the regular expression,
> > then I want it to appears in my new array, otherwise it can be
> > discarded. I have come up with the following code (for example, getting
> > strings than end in 'abba' in an array of string)
> >
> > new_array = (array.collect { |x| if( x =~ /abba$/ ) then x else nil end
> > }).compact
> >
> > It works fine, but I want to know if there's is a more simple way to do
> > this since I do this a lot in my scripts.
> >
> > Thankx,
> > Ben.
> >
> >
>
> --
> Daniel Carrera
> Graduate Teaching Assistant.  Math Dept.
> University of Maryland.  (301) 405-5137
>
>