From: "Einar Magnús Boson" <einarmagnus@...>
Date: 2008-11-18T10:44:14+09:00
Subject: Re: function to select only certain key/value pairs from hash?

>>>
>>
>>
>> That is ridiculously inefficient and weird :)
>>
>> hash = {:a => 1, :b => 2, :c => 3}
>>
>> selected = [:a, :b].map{|key|{key, hash[key]}}
>>
>> p selected
>>
>> # >> [{:a=>1}, {:b=>2}]
>>
>>
>
> and now I see that I was stupd.
> heh. nevermind <.<
>

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}

.