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Python Regular Expressions in Python Introduction to Regular Expressions Word Length

Posted by David Hackett
David Hackett
3,191 Points

Using a variable in an expression quantifier ?

When I try to use "count" as my quantifier here I always get an empty list back

If I run this in my own terminal but have count explicitly defined (e.g. as 4) then I do get expected results... for example:

find_words(4, "dog, cat, baby, balloon, me") ['baby', 'balloon']

(although 4 is still passed I do not use it, I have the number 4 explicitly in the same code line as the snippet here but in the place of "count"

word_length.py 
import re

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

def find_words(count, my_string):
  return re.findall(r'\b\w{count,}', my_string)

1 Answer

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

You'll need to use something like format or convert count into a string and then concatenate the regular expression in order to get at its value.

Here's an example with concatenation:

regex = "\\w{" + str(count) + ",}"