From: Todd Benson <caduceass@...>
Date: 2008-11-18T14:00:32+09:00
Subject: Re: function to select only certain key/value pairs from hash?

On Mon, Nov 17, 2008 at 7:44 PM, Einar Magnús Boson
<einarmagnus@tistron.se> wrote:
> This is what I meant to do, a lot more efficient to look up the values
> you're lookin for than looping through all keys for every element.
>
> hash = {:a => 1,
>                        :b => 2,
>                        :c => 3,
>                        :d => 4,
>                        :str => "test"}
>
> selected = [:a, :d, :str].inject({}){|result, key| result[key]=
> hash[key];result}
>
>
> p selected
>
> # >> {:str=>"test", :a=>1, :d=>4}

You will get nils for none existing keys that way.

selected = [:whatever].inject({}){|result, key| = hash[key]; result}
#=> {:whatever => nil}

If that's what you want, great.

Todd