Inserting a variable into a regex?

Question

This one had me stumped for about 10 min:

'Create a function named find_words that takes a count and a string. Return a list of all of the words in the string that are count word characters long or longer.'

This code is what I came up with. I'm interested in knowing if there is a different solution to this challenge.

Thanks Again!

-Pete

word_length.py

import re

# EXAMPLE:
# >>> find_words(4, "dog, cat, baby, balloon, me")
# ['baby', 'balloon']
def find_words(count, sarg):
  return re.findall(r'\w{%i,}' % count, sarg)

Answer 1 · 2016-02-01T07:16:09Z

February 1, 2016 7:16am

Your code is spot on (I like the use of regex ranges). The regex is looking for a string. and any process of constructing with the correct "count" in the string also works:

# concatenation
re.findall(r'\w{'+ str(count) + ',}', sarg)
# format method
re.findall(r'\w{{{},}}'.format(count), sarg)  # <-- a little clunky having to escape '{' using '{{' etc.
# use explicit counting instead of ranges: stack '\w' add '+' for "or more"
re.findall(r'\w' * count + '+', sarg)

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Pete P

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Inserting a variable into a regex?

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