Python正则表达式匹配世界但排除某些短语

Question

I got the following scenario:

1)car is on fire
2)found fire crews on scene

I want to match fire when keyword "crews" NOT present. The other word, I want to 1) return "fire", and 2) returns nothing.

regex = re.compile(r'\bfire (?!crews)\b')

but it failed to match "car is on fire" due to missing space after fire.

Thanks in advance.

Answer 1

Your regex would be,

\bfire\b(?!.*\bcrews\b)

DEMO

If you want to print the whole line then your regex would be,

.*\bfire\b(?!.*\bcrews\b).*

Python code,

>>> import re
>>> data = """car is on fire
... found fire crews on scene"""
>>> m = re.search(r'\bfire\b(?!.*\bcrews\b)', data, re.M)
>>> m.group()
'fire'
>>> m = re.search(r'.*\bfire\b(?!.*\bcrews\b).*', data, re.M)
>>> m.group()
'car is on fire'

Answer 2

You don't need regex here. You can just check with the in keyword:

if "fire" in line and "crews" not in line:
    print("fire")