From: Jos Backus <jos@...>
Date: 2006-12-21T14:27:58+09:00
Subject: Re: tricky sort for happy visitors of Paris

On Thu, Dec 21, 2006 at 08:05:06AM +0900, William James wrote:
> Jos Backus wrote:
> > More generally:
> >
> > lizzy:~% irb
> > irb(main):001:0> arrondissements = ["Paris 1", "Paris 2","Paris 4", "Paris 3", "Lyon 2", "Lyon 1"]
> > => ["Paris 1", "Paris 2", "Paris 4", "Paris 3", "Lyon 2", "Lyon 1"]
> > irb(main):002:0> sorted_array = arrondissements.sort_by {|e| [e.split(" ")]}
> > => ["Lyon 1", "Lyon 2", "Paris 1", "Paris 2", "Paris 3", "Paris 4"]
> > irb(main):003:0> %                                                              lizzy:~%
> >
> > --
> > Jos Backus
> > jos at catnook.com
> 
> Won't work for
> 
> arrondissements = "Paris 1", "Paris 2","Paris 12", "Paris 3",
>   "Lyon 2", "Lyon 1"
> 
> For the 2nd field, you need a numeric comparison.
> 
> p arrondissements.sort_by {|e|  e.split.inject{|a,b| [a,b.to_i] } }

Oops, you're right, I missed that. Clever use of inject, by the way.

-- 
Jos Backus
jos at catnook.com