计算两个字符串之间的单词数python regexp

Question

I want to check if number of words between two strings in a larger string is < n. For example, suppose I have a string like "a quick brown fox jumps over the lazy dog". I want to see if the distance between strings "brown fox" and "lazy dog" is < 5 in the larger string. What would be a proper python regexp for that?

I tried as per the link . My code was

s='a quick brown fox jumps over the lazy dog'
m=re.search("'brown fox'\W+(?:\w+\W+){1,4}'lazy dog'",s)

but there was no match.

Answer 1

You are trying to match for single quotes, but there aren't any in the string:

>>> re.search("brown fox\W+(?:\w+\W+){1,4}lazy dog", s)
<_sre.SRE_Match at 0x3045850>

>>> re.search("brown fox\W+(?:\w+\W+){1,3}lazy dog", s)
<_sre.SRE_Match at 0x3045920>

>>> re.search("brown fox\W+(?:\w+\W+){1,2}lazy dog", s)
(None)

Answer 2

尝试brown fox\\s+(\\S+\\s+){0,4}lazy dog