How to not match whole word "king" to "king?"?

Question

How do I verify an exact word occurs in a string?

I need to account for cases when a word such as "king" has a question mark immediately following as in the example below.

unigrams this should be False

In [1]: answer = "king"
In [2]: context = "we run with the king? on sunday"

n_grams this should be False

In [1]: answer = "king tut"
In [2]: context = "we run with the king tut? on sunday"

unigrams this should be True

In [1]: answer = "king"
In [2]: context = "we run with the king on sunday"

n_grams this should be True

In [1]: answer = "king tut"
In [2]: context = "we run with the king tut on sunday"

As people mentioned, for the unigram case we can handle it by splitting the string into a list, but that doesn't work for n_grams.

After reading some posts, I think I should attempt to handle using a look behind, but I'm not sure.

Answer 1

return answer in context.split():

>>> answer in context.split()
False

You don't need a regex for this.

If you're looking for keywords:

all([ans in context.split() for ans in answer.split()])

will work with "king tut", but that depends if you want to match strings like:

"we tut with the king"

If you don't, you still don't need a regex (although you should probably use one), given that you want to consider only whole terms (which are properly split, by default, via .split()):

def ngram_in(match, string):
    matches = match.split()
    if len(matches) == 1:
        return matches[0] in string.split()
    words = string.split()
    words_len = len(words)
    matches_len = len(matches)
    for index, word in enumerate(words):
        if index + matches_len > words_len:
            return False
        if word == matches[0]:
            for match_index, match in enumerate(matches):
                potential_match = True
                if words[index + match_index] != match:
                    potential_match = False
                    break
            if potential_match == True:
                return True
    return False

which is O(n*m) on a worst case string and about half as fast as a regex on normal strings.

>>> ngram_in("king", "was king tut a nice dude?")
True
>>> ngram_in("king", "was king? tut a nice dude?")
False
>>> ngram_in("king tut a", "was king tut a nice dude?")
True
>>> ngram_in("king tut a", "was king tut? a nice dude?")
False
>>> ngram_in("king tut a", "was king tut an nice dude?")
False
>>> ngram_in("king tut", "was king tut an nice dude?")
True