From: matt@... (matt neuburg)
Date: 2009-03-29T01:40:03+09:00
Subject: Re: Sorting decimal index numbers?

Matthias Reitinger <reitinge@in.tum.de> wrote:

> matt neuburg wrote:
> > If there are a lot of these, however, it would be much better to do a
> > keyed sort using sort_by. How to create keys depends on what you know
> > about the data. If we knew for a fact that the second half was always
> > between 1 and 99, it would be easy:
> > 
> > arr = arr.sort_by do |x|
> >   x1, x2 = x.split(".")
> >   x1.to_i * 100 + x2.to_i
> > end
> > 
> > If the second half can be any length, though, you'll have to determine
> > the maximum length first, and change that "100" multiplier accordingly.
> 
> Either that or use arrays as sort keys:
> 
>   arr = arr.sort_by do |x|
>     x.split(".").map {|i| i.to_i}
>   end

Yes, that's better; my first answer failed to take into account Array's
existing implementation of the spaceship operator. m.

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