Python Help: Regular expressions not behaving as I might expect

Dogs · 02-04-2011, 08:31 PM

So, I have a file full of IDs and names of various stores that I want to extract either the ID or the store name from.

I got the ID part of it pretty quickly, because they're fixed lengths and at the beginning of the string. The names, however, are variable lengths from 0-50 alphanumeric characters.

the format is:

12345-my store name-
12346-my Big 1 Store Name The Eleventh-

what I'm trying is:

Code:

import re

my_pattern = re.compile('-*-')
storelist = ['12345-my store name-', '12346-my Big 1 Store Name The Eleventh-']

for line in storelist:
    my_store = my_pattern.search(storelist)
    my_store.group()

this isn't how I actually plan to keep it, but I'm new to Python and trying to figure out how to make something like this work so I can write a function that returns a store name at a given position in the list.

What I am wrongly assuming is happening is that the pattern searches for most anything inside of '-'s, but this doesn't appear to be the case.

Instead, it will find a single '-' and print that.

How can I create a pattern that represents a '-', some variable amount of letters/numbers after it, and then another '-'?

ghostdog74 · 02-04-2011, 09:07 PM

no need to use regular expression. You are using Python and Python already has excellent string manipulation built in.
just split on "-" .

Code:

>>> "12346-my Big 1 Store Name The Eleventh-".split("-",2)
['12346', 'my Big 1 Store Name The Eleventh', '']
>>> "12345-my store name-".split("-",2)
['12345', 'my store name', '']

now the 2nd element will be your name, and the 1st element will be your id number. Check the doc for usage of split

Dogs · 02-04-2011, 09:15 PM

Oh hey.. That's fancy!

grail · 02-05-2011, 02:09 AM

Obviously ghostdog's solution is the way to go, but on the topic of regular expressions, I believe yours will match the following:

Code:

-
--
----------------------

And so on, for what you have asked is for it to look for zero or more dashes (-*) followed by a single dash (-). As every entry has at least a single dash in it they should
all return that dash.

Maybe you wanted a pattern more like: '-[a-zA-Z ]+-'

There is the option of character classes too but I did not want to go over the top.

Hope that helps.