用于匹配 Python 中包含撇号的确切单词的正则表达式？

Question

For the purpose of this project, I'm using more exact regex expressions, rather than more general ones. I'm counting occurrences words from a list of words in a text file called I import into my script called vocabWords, where each word in the list is in the format \\bword\\b .

When I run my script, \\bwhat\\b will pick up the words "what" and "what's", but \\bwhat's\\b will pick up no words. If I switch the order so the apostrophe word is before the root word, words are counted correctly. How can I change my regex list so the words are counted correctly? I understand the problem is using "\\b", but I haven't been able to find how to fix this. I cannot have a more general regex, and I have to include the words themselves in the regex pattern.

vocabWords:

\bwhat\b
\bwhat's\b
\biron\b
\biron's\b

My code:

matched = []
regex_all = re.compile('|'.join(vocabWords))
for row in df['test']:
    matched.append(re.findall(regex_all, row))

Answer 1

If you sort your wordlist by length before turning it into a regexp, longer words (like "what's") will precede shorter words (like "what"). This should do the trick.

regex_all = re.compile('|'.join(sorted(vocabWords, key=len, reverse=True)))

Answer 2

There are at least another 2 solutions:

1. Test that next symbol isn't an apostrophe r"\\bwhat(?!')\\b"
2. Use more general rule r"\\bwhat(?:'s)?\\b" to caught both variants with/without apostrophe.