在字符串中找到列表项的整个部分，而不是子部分？

Question

I have a dictionary of keys & values (massively truncated for ease of reading):

responsePolarities = {'yes':0.95, 'hell yes':0.99, 'no':-0.95, 'hell no':-0.99, 'okay':0.70}

I am doing a check to see if any key is in a string passed to my function:

for key, value in responsePolarities.items():
    if key in string:
        return value

Problem is that if, in the passed string, a word such as "know" is in it, the function sees the 'no' in 'know' and returns a -0.95.

I can't add spaces around the 'no' key because it could be the only response provided.

How can I make the function see 'no' as 'no' but not 'know'? Am I correct in thinking this is probably going to need to be a RegExp job, or is there something more simple I'm missing?

I thought about splitting my passed string into individual words, but then I couldn't check for multi-word phrases that modify the response polarity (like no vs. hell no)...

Answer 1

If I understand this correctly, you want to match text that contains your keys, but only if the whole word matches. You can do this using the regex word boundary delimiter \\b . It will match when the word is separated by punctuation, like :no, but not other word characters like know . Here you loop through some strings and for each find the matching keys in the dictionary:

responsePolarities = {'yes':0.95, 'hell yes':0.99, 'no':-0.95, 'hell no':-0.99, 'okay':0.70}

strings = [
    'I know nothing',
    'I now think the answer is no',
    'hell, mayb yes',
    'or hell yes',
    'i thought:yes or maybe--hell yes--'
]

for s in strings:
    for k,v in responsePolarities.items():
        if re.search(rf"\b{k}\b", s):
            print(f"'{s}' matches: {k} : {v}")

'I know nothing' shouldn't match anything. The matches should look like:

'I now think the answer is no' matches: no : -0.95
'hell, mayb yes' matches: yes : 0.95
'or hell yes' matches: yes : 0.95
'or hell yes' matches: hell yes : 0.99
'i thought:yes or maybe--hell yes--' matches: yes : 0.95
'i thought:yes or maybe--hell yes--' matches: hell yes : 0.99

If you are doing a lot of searches, you might consider precompiling the regexes before the loop.