Python正则表达式-替换基于字符串的重复模式

Question

I want to transform the string L^2 MT^-1 to L^2.MT^-1 . The dot replaces the space (\\s) only if it is between two word characters. For example, if the string is 'lbf / s' no replacement will be applied.

str1= 'L^2 M T^-1'

pattern = re.compile(r'(\w+\s\w+)+')
def pattern_match2(m):
    me = m.group(0).replace(' ', '.')
    return me

pattern.sub(pattern_match2, str1) # this produces L2.MT-1

How can i replace the string with dot (.) by repeated patterns?

Answer 1

You can use re.sub directly instead of finding a match and then using str.replace . Also, I'd use \\b instead of \\w since \\w matches any [a-zA-Z0-9_] , while \\b encapsulates it in a smarter way (in essence it is equivalent to (^\\w|\\w$|\\W\\w|\\w\\W) )

import re

print(re.sub(r'\b(\s)\b', '.', 'L^2 M T^-1'))
# L^2.M.T^-1

print(re.sub(r'\b(\s)\b', '.', 'lbf / s'))
# lbf / s