From: Chris Shea <cmshea@...>
Date: 2008-11-18T08:46:49+09:00
Subject: Re: function to select only certain key/value pairs from hash?

On Nov 17, 3:50 pm, Aryk Grosz <tennisbum2...@hotmail.com> wrote:
> Whenever Im coding I usually come across having to create a new hash
> from the key/value pairs of another hash.
>
> For example,
>
> hash = {:a => 1, :b => 2, :c => 3}
>
> I want to do something like this
>
> hash.from_keys(:a,:b) => {:a=> 1, :b=> 2}
>
> Is there something like this already? Perhaps in the facets library? I
> looked and couldn't find anything.
>
> If anybody thinks that I shouldnt even be getting into this situation in
> the first place, please let me know that as well.
> --
> Posted viahttp://www.ruby-forum.com/.

Hmm... I thought there was a built in method for that.  Here's one
way:

hash = {:a => 1, :b => 2, :c => 3}
Hash[*hash.select {|k,v| [:a,:b].include?(k)}.flatten]  #=>
{:b=>2, :a=>1}

HTH,
Chris