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kwcooper/groupbylist.py

Created October 1, 2020 05:29
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Group one list by another list with itertools and python 3+
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groupbylist.py
from itertools import groupby
l1 = [1,1,1,2,2,2,2,2,1,1,1,0,0,0]
l2 = range(len(l1))
[(k, list(group)) for k, group in groupby(l2, key=lambda _, ig=iter(l1): next(ig))]
# Returns [(1, [0, 1, 2]), (2, [3, 4, 5, 6, 7]), (1, [8, 9, 10]), (0, [11, 12, 13])]
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