Python Regex Sentence Finder-Want to Ignore "a.m."

Question

I am developing a regex to find sentences, and I would like to ignore abbreviations that cause the regex to terminate before the end of the sentence. For example, I want to ignore "a.m." so that it returns "At 9:00 a.m. the store opens." instead of "At 9:00 a.m."

def sentence_finder(x):
    RegexObject = re.compile(r'[A-Z].+?(?!a.m.)w+[.?!](?!S)')
    Variable = RegexObject.findall(x)
    return Variable

I get back the following when I run pytest:

def test_pass_Ignore_am():
>       assert DuplicateSentences.sentence_finder("At 9:00 a.m. the store opens.") == ["At 9:00 a.m. the store opens."]
E       AssertionError: assert ['At 9:00 a.m.'] == ['At 9:00 a.m...store opens.']
E         At index 0 diff: 'At 9:00 a.m.' != 'At 9:00 a.m. the store opens.'

What am I doing wrong?

question from:https://stackoverflow.com/questions/65911590/python-regex-sentence-finder-want-to-ignore-a-m

Answer 1

You could use a negative lookbehind to check that after matching a dot, there is not a.m. before it.

[A-Z].*?w[.?!](?<!a.m.)(?!S)

Explanation

• [A-Z] Match a char A-Z
• .*? Match 0+ times any char except a newline as least as possible
• w[.?!] Match a word char followed by either . ? or !
• (?<!a.m.) Negative lookbehind to assert that directly to the left is not a.m.
• (?!S) Assert a whitespace boundary to the right

Regex demo