From: "Eric I." <rubytraining@...>
Date: 2008-02-12T07:24:58+09:00
Subject: Re: Partial index hash search?

On Feb 11, 3:47 pm, Serg Koren <sko...@comcast.net> wrote:
> What's the best way to find all occurances of a string in a hash's  
> index?
>
> That is,
>
> x = { 'Hello' => 1, 'Goodbye' => 2, 'Hello there' => 3}
>
> How do I most efficiently get  1 and 3 to return on a search for  
> 'Hello' in the index of the hash?  I know I can iterate over the  
> index, but is there a better way?
>
> Thanks.

Hi Serg,

Here's one way to do it:


x = { 'Hello' => 1, 'Goodbye' => 2, 'Hello there' => 3}

result = x.keys.select { |k| k.include? "Hello" }.map { |k| x[k] }
p result


There's really no way to avoid iterating over the keys in the hash.
In this case, Enumerable#select is doing that when it produces an
array of the keys that contain "Hello".  That array of keys is
converted into an array of values by using Enumerable#map.

Eric

P.S. It looks like you replied to a posting for Ruby Quiz #156.  Since
this is unrelated to the Ruby Quiz, it would have been preferable to
make a new post.

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