From: Duane Johnson <duane.johnson@...>
Date: 2006-12-21T07:59:00+09:00
Subject: Re: tricky sort for happy visitors of Paris

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On 12/20/06, Jos Backus <jos@catnook.com> 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"]
>

I think that gets us back to the original problem, namely, that numbers with
an unequal number of digits will be incorrectly sorted using due to string
comparison:

irb(main)> arrondissements = ["Paris 1", "Paris 2","Paris 4", "Paris 3",
"Lyon 2", "Lyon 1", "Paris 10"]
irb(main)> arrondissements.sort_by {|e| [e.split(" ")]}
=> ["Lyon 1", "Lyon 2", "Paris 1", "Paris 10", "Paris 2", "Paris 3", "Paris
4"]

Note the position of "Paris 10".  This is why the zero-padding is necessary
in my previous example.

-- 
Duane Johnson
(canadaduane)

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