Python 从list中统计相同值的索引值

from collections import defaultdict

a=[1,2,3,1,2,3]
d = defaultdict(list)
for i, v in enumerate(a):
    d[v].append(i)

Out:
defaultdict(list, {1: [0, 3], 2: [1, 4], 3: [2, 5]})