From: "Einar Magnús Boson" <einarmagnus@...>
Date: 2008-11-18T10:37:21+09:00
Subject: Re: function to select only certain key/value pairs from hash?


On 18.11.2008, at 01:34 , Einar Magnús Boson wrote:

>
> On 17.11.2008, at 23:46 , Chris Shea wrote:
>
>> 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
>>
>
>
> 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}]
>
>
>
>
> Einar Magnús Boson
> +354-661 1649
> einarmagnus@tistron.se
> einar.boson@gmail.com
>
>

and now I see that I was stupd.
heh. nevermind <.<

Einar Magnús Boson
+354-661 1649
einarmagnus@tistron.se
einar.boson@gmail.com