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Python Regular Expressions in Python Introduction to Regular Expressions Word Length

Posted by Gordon Reeder
Gordon Reeder
2,521 Points

Regular expressions code challenge. Help.

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.

It won't pass and I can't see what I'm doing wrong.

word_length.py 
import re
def find_words(a_count, a_string):
  return re.findall(r'\w{a_count,}', a_string)

# EXAMPLE:
# >>> find_words(4, "dog, cat, baby, balloon, me")
# ['baby', 'balloon']

2 Answers

Dan Johnson
Dan Johnson
40,532 Points
Dan Johnson
Dan Johnson
40,532 Points

You'll have to use format or a similar method to do string interpolation:

Format:

regex = r"\w{{{},}}".format(count)

Old method as it's easier to read:

regex = r"\w{%d,}" % count
Gordon Reeder
Gordon Reeder
2,521 Points

Thanks Dan, that worked (first example). I'm not exactly sure why.

Dan Johnson
Dan Johnson
40,532 Points
Dan Johnson
Dan Johnson
40,532 Points

The first method looks odd since format uses {} for replacement. So you have to add extras to escape them to place the literal pair.

Brian Saunders
Brian Saunders
5,780 Points
Brian Saunders
Brian Saunders
5,780 Points

I'm not sure why I didn't think of this myself. That totally works! Thanks.