From: David Vallner <david@...>
Date: 2006-01-11T13:42:22+09:00
Subject: Re: Stupid question from a Ruby newb

Will wrote:

>Hi folks, I know that this is a really simple question, and there must
>be many ways to do it in Ruby...  but what I'm looking for is an
>elegant way to take a collection of objects and create a hash mapping
>one attribute of the object as the key and the other as the value.  So
>far what I am doing is this:
>
>objects = some_method_to_return_collect( method_params )
>myHash = Hash.new
>
>@objects.each do |object|
>  myHash[ object.key ] = object.value
>end
>
>I played around with doing something like:
>
>@myHash = objects.map do |object| [ object.key => object.value ] end
>
>But that returns an array of single-value hashes, which is not exactly
>what I am trying to do.
>
>I know this is a stupid question, and probably pointless because I do
>know ways to do it, but I would really like the know the Ruby Way to do
>this.  Ruby seems so given to elegant code that my code above really
>bugs me for some reason.
>
>Thanks all!
>
>-Will
>
>
>  
>
There are no stupid questions, only stupid people.

The solution you first wrote where you're iterating over the array is as 
good as any, i would probably use that.

If you like Ever So Cool one-liners, this one might also work:

    myHash = objects.inject({}){|hash, item| hash[item.key] =
    item.value; hash}

It does pretty much completely the same, except were this Smalltalk, the 
block wouldn't be a closure and therefore a horse's butthair more 
memory-efficient solution.

David Vallner