python regex word repeat time

Question

I got the following scenarios:

1) car collisions effect 3 right lanes
2) 3 car collisions effect right lanes

I want to figure out number of lanes instead of number of collision. To be specific I want extract number and "right lanes" with less than two \bwords\b in between.

\b(\d)<I want to limit 2 words here>\s*(lane[s]?)
OR
\b(\d)<I want to limit 10 characters here>\s*(lane[s]?)

Answer 1

Using lookahead:

import re
s1 = "1) car collisions effect 3 right lanes"
s2 = "2) 3 car collisions effect right lanes"
print re.findall("(\d+)(?=(?:\s+\w+){,2}\s+right lanes)", s1) 
print re.findall("(\d+)(?=(?:\s+\w+){,2}\s+right lanes)", s2) 

Gives:

['3']
[]