如何删除字符串中最后一个数字之后的所有内容

Question

I have strings like this:

w = 'w123 o456 t789-- --'

My goal is to remove everything after the last number, so my desired output would be

w123 o456 t789

It is not always the same ending, so -- -- is just one example.

import re

re.sub('(.*?)(\d)', '', w)

gives me

'-- --'

How can I modify the command so that it removes this part?

Answer 1

You can use:

>>> w = 'w123 o456 t789-- --'
>>> re.sub(r'\D+$', '', w)
'w123 o456 t789'

\\D+$ will remove 1 or more non-digit characters before end anchor $ .

Answer 2

The point is that your expression contains lazy dot matching pattern and it matches up to and including the first one or more digits.

You need to use greedy dot matching pattern to match up to the last digit, and capture that part into a capturing group. Then, use a r'\\1' backreference in the replacement pattern to restore the value in the result.

This will work with 1-line strings:

re.sub(r'(.*\d).*', r'\1', w)

or with anchors and also supporting strings with linebreaks:

re.sub(r'^(.*\d).*$', r'\1', w, flags=re.S)

Python demo:

import re
w = 'w123 o456 t789-- --'
print(re.sub(r'^(.*\d).*$', r'\1', w, flags=re.S))
# => w123 o456 t789

Answer 3

st = 'w123 o456 t789-- --'
print st.rstrip()
"w123 o456 t789'