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

There's no need to use re.sub if your replacement is so simple - simply use str.replace:

s = 'e004_n07'
s.replace('0', '') # => 'e4_n7'