Python 3 Finding the last number in a string

Question

How can I find the last number in any big string?

For eg in the following string I want 47 as the output:

'tr bgcolor="aa77bb"td>font face="verdana"color="white" size="2">b>Total/b>/font>/td>\td>font face="verdana"color="white" size="2">b>47/b>/font>/td>/tr>'

PS: We don't know the number. The number 47 is just an example. It can be any number from 0 to 900.

Is the HTML broken in the source? – ninMonkey Jun 10 '13 at 00:19 — ninMonkey, Jun 10 '13 at 00:19

score 26 · Answer 1 · edited May 23 '17 at 12:10

26

>>> import re
>>> text = 'tr bgcolor="aa77bb"td>font face="verdana"color="white" size="2">b>Total/b>/font>/td>\td>font face="verdana"color="white" size="2">b>47/b>/font>/td>/tr>'
>>> re.findall(r'\d+', text)[-1]
'47'

If you need to match floating points there's always this

For very long strings this is more efficient:

re.search(r'\d+', text[::-1]).group()[::-1]

edited May 23 '17 at 12:10

Community

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answered Jun 09 '13 at 07:05

jamylak

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It gives the inverted answer, I guess. You can just reverse the final string, then. – Sukrit Kalra Jun 09 '13 at 07:05
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Just realised you can just use `re.findall` anyway (was thinking backwards) – jamylak Jun 09 '13 at 07:07
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By the way, reversing is way-way better for long strings. But this won't work with referenced regexp for floats, of course. – kirelagin Jun 09 '13 at 07:30
@kirelagin I thought that at first, but then I assumed it would never be very useful but I'll add it back – jamylak Jun 09 '13 at 08:32

score 2 · Answer 2 · answered Jun 09 '13 at 07:46

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I guess I don't know enough about the implementation details / performance of finding a bunch of results and choosing the last, vs just finding the last to begin with (didn't do any performance comparisons); but, this very well might be faster:

>>> text = 'tr bgcolor="aa77bb"td>font face="verdana"color="white" size="2">b>Total/b>/font>/td>\td>font face="verdana"color="white" size="2">b>47/b>/font>/td>/tr>'
>>> import re
>>> re.search(r'(\d+)\D+$', text).group(1)
'47'

answered Jun 09 '13 at 07:46

Matt Anderson

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+1 I like this better than `re.findall`. I have a similar second version that I re-added to my answer which short circuits so it would be more efficient (not sure about speed) but this looks nicer – jamylak Jun 09 '13 at 08:37
Replace the '+'s with '*'s to also match the empty string and digits flush right, respectively. E.g., `re.search(r'(\d*)\D*$', '').group(1)` returns `''`. – gherson Aug 17 '19 at 22:09

Python 3 Finding the last number in a string

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