RLE 2D array encoding/decoding

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import re
from itertools import groupby


def encode_rle(level):
    return '\n'.join(
        [
            ''.join(
                [key + str(len(list(group))) for key, group in groupby(row)]
            ) for row in level
        ]
    )


def decode_rle(level):
    decoded_level = []
    for row in level.split('\n'):
        decoded_row = []
        for elt, k in re.findall(r'([A-Za-z_]+)(\d+)', row):
            decoded_row.extend([elt] * int(k))
        decoded_level.append(decoded_row)
    return decoded_level


level = [
    ['a', 'a', 'a', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'c', 'c', 'b', 'b'],
    ['b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'a', 'a'],
    ['a', 'c', 'c', 'c', 'b', 'c', 'a', 'b', 'a', 'a', 'a', 'b', 'b', 'c']
]

enc = encode_rle(level)
dec = decode_rle(enc)

assert dec == level