Python Regular Expression; replacing a portion of match

Question

How would I limit match/replacement the leading zeros in e004_n07? However, if either term contains all zeros, then I need to retain one zero in the term (see example below

Answer 1

If your requirement is that you MUST use regex, then below is your regex pattern:

>>> import re
>>> s = 'e004_n07'
>>> line = re.sub(r"0", "", s)
>>> line
'e4_n7'

However it is recommended not to use regex when there is other efficient way to perform the same opertaion, i.e. using replace function

>>> line = s.replace('0', '')
>>> line
'e4_n7'