Python 3 Finding the last number in a string

问题:

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.

回答1:

>>> 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]

回答2:

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'

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