Python 二维字典定义

初始化二维字典

二维字典形如, 值为字典：
C={“a”: {“b”: {2}}, “b”: {“c”: {1}}}

from collections import defaultdict
a = {"a": 1, "b": 2, "c": 3}
C = defaultdict(lambda: defaultdict(lambda: 0))  # 初始化
for i in a.keys():
    for j in a.keys():
        C[i][j] = a[i] * a[j]
for user, related_user in C.items():
    for v, item in related_user.items():
        print("%s-%s: %d" % (user, v, item))