From: Rob Biedenharn <Rob@...>
Date: 2009-05-19T09:55:12+09:00
Subject: Re: Sorting numbers as strings


On May 18, 2009, at 1:01 PM, Robert Klemme wrote:

> On 18.05.2009 17:37, Rob Biedenharn wrote:
>
>> If you do need to consider things like "FastEthernet..." v.   
>> "GigabitEthernet...", then perhaps you want something like this  
>> which  breaks the original string into digits and non-digits and  
>> converts the  digits to be integers.
>> puts DATA.sort_by {|s| s.scan(/\d+|\D+/).map {|x| x =~ /\d+/ ?   
>> x.to_i : x } }
>
> Good point!  Here's an interesting variant:
>
> puts DATA.sort_by {|s| s.scan(/(\d+)|\D+/).map { $1 ? $1.to_i : $& } }
>
> Kind regards
>
> 	robert
> -- 
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/

Interesting, but "wrong" in that it doesn't sort the way the OP wanted.
Actually, since all the regexp applications have been applied by #scan  
before the #map happens, the values of $1 and $& are effectively  
constants and no sorting happens at all.

However, that did inspire me to make my version a little better.

puts DATA.sort_by {|s| s.scan(/(\d+)|(\D+)/).map {|(n,s)| s ||  
n.to_i } }

I'd rather make the variables local than invoke the Perlish Regexp  
globals (even if they did were assigned in the block the way you  
expected).  It could be even more readable if (n,s) were replaced with  
(digits,nondigits), but it looks OK to me with n and s.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com