python: how to split this string with a regex?

Question

Simple one here but I'm fairly new to Python.

I have a string like this:

this is page one of an article 
<!--pagebreak page two --> this is page two 
<!--pagebreak--> this is the third page 
<!--pagebreak page four --> last page
// newlines added for readability

I need to split the string using this regex:  - the idea is that sometimes the  comments have a 'title' (which I use in my templates), other times they don't.

I tried this:

re.split("<!--pagebreak*.?-->", str)

which returned only the items with 'titles' in the pagebreak (and didn't split them correctly either). What am I doing wrong here?

skunkfrukt · Accepted Answer · 2012-10-04 08:54:15Z

2

Change *.? into .*?:

re.split("<!--pagebreak.*?-->", str)

Your current regex accepts any number of literal k's, optionally followed by (any character).

Also, I would recommend using raw strings (r"...") for your regular expressions. It's not necessary in this case, but it's an easy way to spare yourself a few headaches.

edited Oct 4, 2012 at 8:54

answered Oct 4, 2012 at 8:41

skunkfrukt

1,5701 gold badge13 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

jpm Over a year ago

.*? doesn't make sense in regex.

skunkfrukt Over a year ago

@jpm Yes it does. It's a . with a lazy * quantifier.

Hans Then Over a year ago

How can you forget about laziness? It is the greatest of all programming virtues.

skunkfrukt Over a year ago

@MattAndrews Not at all. We all make typos from time to time.

halex · Accepted Answer · 2012-10-04 08:41:35Z

2

You swapped the . with the *. The correct regex is:

<!--pagebreak.*?-->

answered Oct 4, 2012 at 8:41

halex

16.4k6 gold badges60 silver badges67 bronze badges

Comments

damzam · Accepted Answer · 2012-10-04 08:52:22Z

2

Definitely an issue of swapping the . and *. "." matches all and the asterisk indicates that you'll take as many characters as you can get (limited of course by the non-greedy qualifier "?")

import re

s = """this is page one of an article 
<!--pagebreak page two --> this is page two 
<!--pagebreak--> this is the third page 
<!--pagebreak page four --> last page"""

print re.split(r'<!--pagebreak.*?-->', s)

Outputs:

['this is page one of an article \n', ' this is page two \n', ' this is the third page \n', ' last page']

answered Oct 4, 2012 at 8:52

damzam

1,9611 gold badge15 silver badges18 bronze badges

Collectives™ on Stack Overflow

python: how to split this string with a regex?

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related