Remove Last instance of a character and rest of a string

Question

If I have a string as follows:

foo_bar_one_two_three

Is there a clean way, with RegEx, to return: foo_bar_one_two?

I know I

Answer 1

One way is to use rfind to get the index of the last _ character and then slice the string to extract the characters up to that point:

>>> s = "foo_bar_one_two_three"
>>> idx = s.rfind("_")
>>> if idx >= 0:
...     s = s[:idx]
...
>>> print s
foo_bar_one_two

You need to check that the rfind call returns something greater than -1 before using it to get the substring otherwise it'll strip off the last character.

If you must use regular expressions (and I tend to prefer non-regex solutions for simple cases like this), you can do it thus:

>>> import re
>>> s = "foo_bar_one_two_three"
>>> re.sub('_[^_]*$','',s)
'foo_bar_one_two'