可以使用re.findall（）从字符串中获取匹配字符。排序结果和排序模式之间的比较将处理顺序和字符计数的差异。

import re

testString = "polymmorphiiic"

for p in ("ppy", "ooyc", "ciii", "pmy", "iy", "yrz"):
    print(p,"matches:",sorted(p) ==  sorted(re.findall(f"[{p}]",testString)))

ppy matches: True
ooyc matches: True
ciii matches: True
pmy matches: False
iy matches: False
yrz matches: False

注意，你不需要正则表达式来实现这个过程，一个集合就足以过滤匹配的字符：

for p in ("ppy", "ooyc", "ciii", "pmy", "iy", "yrz"):
    matches = set(p).intersection
    print(p,"matches:",sorted(p) == sorted(filter(matches,testString)))

即使是顺序搜索也会起作用：

for p in ("ppy", "ooyc", "ciii", "pmy", "iy", "yrz"):
    print(p,"matches:",sorted(p) == sorted(filter(p.__contains__,testString)))