CODEWITHSUNDEEP
pythonregex
kjfletch
kjfletch

Reputation: 5494

Can someone explain this Python re.sub() unexpected output?

I am using Python 2.6 and am getting [what I think is] unexpected output from re.sub()

>>> re.sub('[aeiou]', '-', 'the cat sat on the mat')
'th- c-t s-t -n th- m-t'
>>> re.sub('[aeiou]', '-', 'the cat sat on the mat', re.IGNORECASE)
'th- c-t sat on the mat'

If this output is what is expected, what is the logic behind it?

Upvotes: 3

Views: 1009

Answers (3)

twasbrillig
twasbrillig

Reputation: 18841

In case you've upgraded since asking this question. If you are using Python 2.7+, you don't need to use re.compile. You can call sub and specify flags with a named argument.

>>> import re
>>> re.sub('[aeiou]', '-', 'the cat sat on the mat', flags=re.IGNORECASE)
'th- c-t s-t -n th- m-t'

Reference: https://docs.python.org/2/library/re.html#re.sub

Upvotes: 0

ymv
ymv

Reputation: 2173

To pass flags you can use re.compile

expression = re.compile('[aeiou]', re.IGNORECASE)
expression.sub('-', 'the cat sat on the mat')

Upvotes: 4

falstro
falstro

Reputation: 35667

Yes, the fourth parameter is count, not flags. You're telling it to apply the pattern twice (re.IGNORECASE = 2).

Upvotes: 7

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