From: Peter Ertl <pertl@...>
Date: 2006-06-14T18:59:51+09:00
Subject: Re: impossible to sort a hash by key?

> h={:c=> 1, :b=> 2, :a => 3}
> a=[]
> h.keys.sort_by {|s| s.to_s}.each {|key| puts h[key] }
> puts a

=> [[:a, 3], [:b, 2], [:c, 1]]



-------- Original-Nachricht --------
Datum: Wed, 14 Jun 2006 18:48:06 +0900
Von: Paul Battley <pbattley@gmail.com>
An: ruby-talk@ruby-lang.org
Betreff: Re: impossible to sort a hash by key?

> On 14/06/06, Matthew Harris <shugotenshi@gmail.com> wrote:
> > Hashes are unordered, an "ordered hash" is an oxymoron.
> > If you need a hash to be ordered, the easiest way is to use an array.
> ...
> >   => [[:a, 1], [:b, 2], [:c, 3], [:d, 4]]
> 
> And you can then use assoc to look up the corresponding element:
> 
> a = [[:a, 1], [:b, 2], [:c, 3], [:d, 4]]
> a.assoc(:c)[1] #=> 3
> 
> The look-up performance for large arrays will be far inferior to that
> of a hash, however.
> 
> Paul.