From: Aaron Vegh <aaron@...>
Date: 2009-03-28T11:57:53+09:00
Subject: Re: Sorting decimal index numbers?

Hi Matt,
Are you _the_ Matt Neuburg, of AppleScript fame? It's a privilege to 
have an answer from you!

matt neuburg wrote:

> These are not numbers; they're strings. Or at least, they need to be; if
> they weren't, 1.1 and 1.10 would be indistinguishable. 

Yes, I think this was becoming my assumption. The head-scratcher for me 
was trying to determine if this sort of numbering scheme ("the 
hierarchical list", if you will) was a special case in Ruby or 
generally. But in my model right now (this is for a Rails project) it's 
set as a string.

> 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

And it turns out that a hundred is more than enough in this case. Thanks 
to you, and to Yossef above, for a working solution.

Cheers!
Aaron.
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