From: brabuhr@...
Date: 2010-09-21T03:05:56+09:00
Subject: Re: An elegant way...

On Mon, Sep 20, 2010 at 1:10 PM, F. Senault <fred@lacave.net> wrote:
> The method takes one argument, an array containing a sorted list of
> strings representing episodes numbers.  The episodes numbers are either
> a number ('1', '12') or prefixed with a letter ('S1' for special 1).  My
> goal is to find sequences in the numbers and join them with dashes :
>
>>> RAniDBTools.format_episodes_list([ '1', '2', '3', '4', '6', '7', '9', 'S1', 'S2' ])
> => "1-4, 6-7, 9, S1-S2"
>>> RAniDBTools.format_episodes_list([ '1', '2', 'S3', 'S4', 'S5', 'O6' ])
> => "1-2, S3-S5, O6"
>
> Here's the code ; what can I do to improve this ?

I wouldn't call this an improvement:

def format_episodes_list a
  z = []
  z << a.inject([""]){|i,j| i.last.succ==j ? i << j : (z << i ; [j])}
  z[1..-1].map{|b| b.size==1?b:"#{b.first}-#{b.last}"}.join(", ")
end

puts format_episodes_list([ '1', '2', '3', '4', '6', '7', '9', 'S1', 'S2' ])
#=> 1-4, 6-7, 9, S1-S2
puts format_episodes_list([ '1', '2', 'S3', 'S4', 'S5', 'O6' ])
#=> 1-2, S3-S5, O6
puts format_episodes_list([ '1', '2', '9', '10', 'S9', 'S10' ])
#=> 1-2, 9-10, S9, S10

(And, I'm guessing that the last one there isn't correct :-)