from itertools import groupby sm='aabccaaddbb' print [[k, len(list(g))] for k, g in groupby(sm)] output: [['a', 2], ['b', 1], ['c', 2], ['a', 2], ['d', 2], ['b', 2]]
from itertools import groupby sm='aabccaaddbb' print [[k, len(list(g))] for k, g in groupby(sm)] output: [['a', 2], ['b', 1], ['c', 2], ['a', 2], ['d', 2], ['b', 2]]