Python - how to multiply characters in string by number after character

Question

Title, for example I want to make 'A3G3A' into 'AAAGGGA'. I have this so far:

if any(i.isdigit() for i in string):
    for i in range(0, len(string)):
        if string[i].isdigit():
             (i am lost after this)

Answer 1

Here's a simplistic approach:

string = 'A3G3A'

expanded = ''

for character in string:
    if character.isdigit():
        expanded += expanded[-1] * (int(character) - 1)
    else:
        expanded += character

print(expanded)

OUTPUT: AAAGGGA

It assumes valid input. It's limitation is that the repetition factor has to be a single digit, e.g. 2 - 9. If we want repetition factors greater than 9, we have to do slightly more parsing of the string:

from itertools import groupby

groups = groupby('DA10G3ABC', str.isdigit)

expanded = []

for is_numeric, characters in groups:

    if is_numeric:
        expanded.append(expanded[-1] * (int(''.join(characters)) - 1))
    else:
        expanded.extend(characters)

print(''.join(expanded))

OUTPUT: DAAAAAAAAAAGGGABC