Re: Help with Regexp, \b
On May 30, 1:30 am, andrew cooke and...@acooke.org wrote: That's what I thought it did... Then I read the docs and confused empty string with space(!) and convinced myself otherwise. I think I am going senile. Not necessarily. Conflating concepts like string containing whitespace, string containing space(s), empty aka 0-length string, None, (ASCII) NUL, and (SQL) NULL appears to be an age- independent problem :-) -- http://mail.python.org/mailman/listinfo/python-list
Help with Regexp, \b
This is a bit embarassing, but I seem to be misunderstanding how \b
works in regexps.
Please can someone explain why the following fails:
from re import compile
p = compile(r'\bword\b')
m = p.match(' word ')
assert m
My understanding is that \b matches a space at the start or end of a
word, and that word is a word - http://docs.python.org/library/re.html
What am I missing here? I suspect I am doing something very stupid.
Thanks,
Andrew
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Re: Help with Regexp, \b
\b is NOT spaces
p = re.compile(r'\sword\s')
m = p.match(' word ')
assert m
m.group(0)
' word '
On Sat, May 29, 2010 at 8:34 PM, andrew cooke and...@acooke.org wrote:
This is a bit embarassing, but I seem to be misunderstanding how \b
works in regexps.
Please can someone explain why the following fails:
from re import compile
p = compile(r'\bword\b')
m = p.match(' word ')
assert m
My understanding is that \b matches a space at the start or end of a
word, and that word is a word - http://docs.python.org/library/re.html
What am I missing here? I suspect I am doing something very stupid.
Thanks,
Andrew
--
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--
http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regexp, \b
andrew cooke and...@acooke.org wrote:
Please can someone explain why the following fails:
from re import compile
p = compile(r'\bword\b')
m = p.match(' word ')
assert m
My understanding is that \b matches a space at the start or end of a
word, and that word is a word - http://docs.python.org/library/re.html
What am I missing here? I suspect I am doing something very stupid.
You misunderstand what \b does: it doesn't match a space, it matches a 0
length string on a boundary between a non-word and a word.
Try:
p.match(' word ', 1).group(0)
and you'll see that you are only match the word, not the surrounding
puctuation.
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Re: Help with Regexp, \b
Also what you are probably looking for is this I guess,
p = re.compile(r'\bword\b')
m = p.match('word word')
assert m
m.group(0)
'word'
On Sat, May 29, 2010 at 8:44 PM, Shashwat Anand anand.shash...@gmail.comwrote:
\b is NOT spaces
p = re.compile(r'\sword\s')
m = p.match(' word ')
assert m
m.group(0)
' word '
On Sat, May 29, 2010 at 8:34 PM, andrew cooke and...@acooke.org wrote:
This is a bit embarassing, but I seem to be misunderstanding how \b
works in regexps.
Please can someone explain why the following fails:
from re import compile
p = compile(r'\bword\b')
m = p.match(' word ')
assert m
My understanding is that \b matches a space at the start or end of a
word, and that word is a word - http://docs.python.org/library/re.html
What am I missing here? I suspect I am doing something very stupid.
Thanks,
Andrew
--
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--
http://mail.python.org/mailman/listinfo/python-list
Re: Help with Regexp, \b
On May 29, 11:24 am, Duncan Booth duncan.bo...@invalid.invalid
wrote:
andrew cooke and...@acooke.org wrote:
Please can someone explain why the following fails:
from re import compile
p = compile(r'\bword\b')
m = p.match(' word ')
assert m
[...]
You misunderstand what \b does: it doesn't match a space, it matches a 0
length string on a boundary between a non-word and a word.
[...]
That's what I thought it did... Then I read the docs and confused
empty string with space(!) and convinced myself otherwise. I
think I am going senile.
Thanks very much!
Andrew
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