Python: Count the consecutive characters at the beginning of a string

Question

I want to count how many leading repeat characters at the beginning of a string. So far the code I wrote:

def count_characters(s, target):
    counter = 0
    for i in range(len(s)):
        if s[i] == target:
            counter += 1
        else:
            return counter

It works. Now I just curious if there is a simpler way to get it done in one or two lines instead of writing an extra function?

Answer 1

If you strip the characters from the beginning, then you are left with a shorter string and can subtract its length from the original, giving you the number of characters removed.

return len(s) - len(s.lstrip(target))

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Note: Your shown code will immediately return 0 if the first character does not match target . If you want to check if there is any repeated first character, you don't need to have target and can just use s[0]

Answer 2

You could use next and a range :

return next(i+1 for i in range(len(s)) if s[i] != s[0], len(s))