python regular expression exclude from match string

Question

I have 3 strings

a ="keep the your pass ABCDEFG other text"
b ="your pass: TESTVALUE other text"
c ="no pass required other text"

I want to get capital values after pass, like this

re.match(r'.*\spass:?\s([a-zA-Z]+).*',a,re.I).group(1)
re.match(r'.*\spass:?\s([a-zA-Z]+).*',b,re.I).group(1)

but I want to exclude "no pass", which is I don't want re to match to c string, how do I do that?

Solution: Thanks eyquem and ovgolovin

I will take eyquem's suggestion of re.search('no\s+pass|pass:?\s+([A-Z]+)')

eyquem · Accepted Answer · 2011-10-03 12:26:21Z

3

import re

for x in ("keep the your pass ABCDEFG other text",
          "your pass: TESTVALUE other text",
          "no pass required other text"):
    print re.search('no\s+pass|pass:?\s+([A-Z]+)',x).group(1)
A-Z]+)'

result

ABCDEFG
TESTVALUE
None

answered Oct 3, 2011 at 12:26

eyquem

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1 Comment

kiminoa Over a year ago

Nice. I was hoping to use a re.findall for something similar, but it doesn't use group(x). Hrm.

ovgolovin · Accepted Answer · 2011-10-03 11:56:10Z

1

It's not OK to use match here. It's preferable to use search for such cases.

re.search(r'(?<!no\s)pass:?\s+([A-Z]+)',a).group(1)

It would be better to write it this way:

re.search(r'(?<!no\s*)pass:?\s+([A-Z]+)',a).group(1)

, but unfortunatelly the current version of regex engine doesn't support infinite lookbehinds.

edited Oct 3, 2011 at 11:56

answered Oct 3, 2011 at 11:50

ovgolovin

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1 Comment

ovgolovin Over a year ago

@user976557 Please, read why it's preferable to use search, not match (I provided the link).

mb14 · Accepted Answer · 2011-10-03 12:04:50Z

1

A solution would be to first , filter everything which doesn't contains 'no pass' and then search for pass. Doing two steps might seem a bit heavy but you will avoid lots of problems by doing it this way. You are trying to solve two problems at the same time (and apparently you are struggling to do it) so just separate the two problems.

answered Oct 3, 2011 at 12:04

mb14

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