From: Riccardo Cecolin <rikiji@...>
Date: 2010-03-23T03:33:51+09:00
Subject: Re: Sorting keys of hash based on value

Aldric Giacomoni wrote:
> Let's say we have this contrived example:
>
> hash = {:a => {:happy => 5},
>         :b => {:happy => 4},
>         :c => {:happy => 7}
> }
>
> I would like to get the keys sorted by descending :happy value, like so:
>
> [:c, :a, :b]
>
> How would I do this?
> The best I've come up with is this:
>
> irb(main):018:0> hash.sort_by { |x, y| -y[:happy] }
> => [[:c, {:happy=>7}], [:a, {:happy=>5}], [:b, {:happy=>4}]]
>
> It's not elegant :(
>   
Do you want keys or the whole hash?

irb(main):015:0> hash.keys.sort { |a,b| hash[b][:happy] <=>
hash[a][:happy] }
=> [:c, :a, :b]