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Python Regular Expressions in Python Introduction to Regular Expressions Word Length

Jason Smith
Jason Smith
8,668 Points

bummer: 'NoneType' object not iterable

i tried to put everything on one line, what mistake did i make?

word_length.py
import re

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

2 Answers

Steven Parker
Steven Parker
228,978 Points

Part of the issue is that you don't want the literal word "count" in your RegEx expression.

Instead, use a mechanism like concatenation, the "format" function, or an "f-string" to include the value of the "count" variable (as a string) in the expression.

Also, "search" will only give the first match. To get them all, use "findall" instead — and you won't need "list".

Steven Parker
Steven Parker
228,978 Points

The "f-string" is a relatively new feature in Python that does token substitution in a string without needing the "format" method. For example:

print("My name is {}.".format(name))  # format method
print(f"My name is {name}.")          # f-string method

It's a bit tricky to use f-strings with regex, but it's possible with proper escaping.

Happy coding!

Jason Smith
Jason Smith
8,668 Points

what's an f-string?