regex matching question

[Gabriel Genellina]

En Sat, 19 May 2007 19:40:39 -0300, bullockbefriending bard  
<kinch1967 at gmail.com> escribió:

> from my cursory skimming of friedl, i get the feeling that the all
> pairs different constraint would give rise to some kind of fairly
> baroque expression, perhaps likely to bring to mind the following
> quotation from samuel johnson:
>
>  "Sir, a woman's preaching is like a dog's walking on his hind legs.
> It is not done well; but you are surprised to find it done at all."

Try this, it's not as hard, just using match and split (with the regular  
expression propossed by MR):

import re
regex = re.compile(r'(\d+,\d+/){5}\d+,\d+')

def checkline(line):
     if not regex.match(line):
         raise ValueError("Invalid format: "+line)
     for pair in line.split("/"):
         a, b = pair.split(",")
         if a==b:
             raise ValueError("Duplicate number: "+line)

Here "all pairs different" means "for each pair, both numbers must be  
different", but they may appear in another pair. That is, won't flag  
"1,2/3,4/3,5/2,6/8,3/1,2" as invalid, but this wasn't clear from your  
original post.

-- 
Gabriel Genellina