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Python Regular Expressions in Python Introduction to Regular Expressions Word Length

Posted by Kristine Saryan
Kristine Saryan
1,386 Points

Not sure what I'm doing wrong

The instructions: 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.

I know num is becoming part of the string, but I'm not sure how else to do this.

word_length.py 
import re

def find_words (num, my_string):
    my_list= []
    my_list.append(re.findall(r'\w{num,}', my_string))
    return my_list
# EXAMPLE:
# >>> find_words(4, "dog, cat, baby, balloon, me")
# ['baby', 'balloon']

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,457 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

There are two issues.

  • num Needs to be formatted into the regex. Currently it's just the characters "num"

  • re.findall() returns a list so it doesn't need to be appended into another list. Simply assign the results to my_list

Michael Kurfis
Michael Kurfis
6,584 Points

Shouldn't 

word_list = (re.findall(r'\w{{},}'.format(count), string))

work?

Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

Michael, format can be confused by the regex braces vs the format placeholders. The regex braces need to escaped by doubling them:

r'\w{{{},}}'.format(count)

which can become hard to read.

Michael Kurfis
Michael Kurfis
6,584 Points
Michael Kurfis
Michael Kurfis
6,584 Points

Thanks, Chris!