import re >>> re.sub("abcdefgh", "a", "A") 'A' >>> re.sub("a", "A", "abcdefgh") 'Abcdefgh' >>> re.sub("[ae]", "A", "abcdefgh") 'AbcdAfgh' >>> re.sub("a.*e", "A", "abcdefgh") 'Afgh' >>> re.sub("(a.*e)", r" \1 ", "abcdefgh") ' abcde fgh'