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Python Regular Expressions in Python Introduction to Regular Expressions Negated Numbers

Posted by simplyb
simplyb
27,883 Points

Negative Numbers Task Help

Hello,

I cant work out why my reg ex is returning numbers in pairs, and misses off the zero at the end?

Please help :(

negate.py 
import re

string = '1234567890'

good_numbers = (re.findall(r"[\d][^5678]", string))

2 Answers

simplyb
simplyb
27,883 Points

I was completely overthinking it, the solution was simply: good_numbers = (re.findall(r"[^567]", string))

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

Glad you worked it out! Working through your original solution, the regex makes the following matches:

  • "12" since 2 is not in "5678"
  • "34" since 4 is not in "5678"
  • skips 5 since 6 is in "5678"
  • skips 6 since 7 is in "5678"
  • skips 7 since 8 is in "5678"
  • "89" since 9 is not in "5678"
  • "0" is skipped since there aren't any more characters in pattern