Replace Repeats

replace_repeats.py

"""
Given a string that contains only digits from 0 to 9 and a number `n`, replace each consecutive run of `n` with its length.
> replaceRepeats('1234500362000440', 0)
1234523623441
> replaceRepeats('000000000000', 0)
12
> replaceRepeats('123456789', 1)
123456789

Email: https://buttondown.com/cassidoo/archive/the-beginning-is-the-word-and-the-end-is-silence/
"""

def replace_repeats(word, number):
    final_string, prev_char, count = "", "", 0
    for char in word:
        # keep counting when the characters match
        if int(char) == number:
            count += 1
        else:
            # when characters do not match, decide if it is a single match, more than one character match, or no match.
            # depending on the condition, do operation.
            if count > 1:
                final_string += str(count)
                final_string += char
            elif count == 1:
                final_string += prev_char
                final_string += char
            else:
                final_string += char
            count = 0
        prev_char = char
    # Make sure all the strinngs are appended before returning, no dangling characters
    if count == 0:
        return final_string
    else:
        return (final_string + str(count))

assert replace_repeats('1234500362000440', 0) == str(1234523623441)
assert replace_repeats('000000000000', 0) == str(12)
assert replace_repeats('123456789', 1) == str(123456789)