创建任意长度的嵌套字典

Question

我有以下问题。我有一个像下面这样的嵌套字典

A = {'A':{'STATES':['0','1','2']}, 'B':{'STATES':['10','20']}}

我最终想要构建的是一个包含STATES所有可能组合的嵌套字典。所以对于A中已知的键数是微不足道的

_dict = {}
for s in A['A']['STATES']:
if s not in _dict:
_dict[s] = {}
for s1 in A['B']['STATES']:
_dict[s][s1] = 0

这给

{'0': {'10': 0, '20': 0}, '1': {'10': 0, '20': 0}, '2': {'10': 0, '20': 0}}

就是我想要的。但是我事先不知道A中的键数。这将是一个有效的解决方案，以相同的任意数量的元素在A?

编辑

例如，如果有三个元素，我将使用

{'0': {'10': {'100':0}, '20': {'100':0}, '1': {'10': {'100':0}, '20': {'100':0}, '2': {'10': {'100':0}, '20': {'100':0}}

Answer 1

这个问题有点复杂，但可以分为三个部分:

1. 解析所有的值，将一个列表映射到每个有效的键
2. 获取按字典插入顺序排列的所有组合的列表
3. 将元组列表转换为嵌套字典，循环遍历元组本身的值-因为我们不知道它的长度。

import itertools
A = {'A':{'STATES':['0','1','2']}, 'B':{'STATES':['10','20']}, 'C':{'STATES':['100']}}
# 1. get your dictionary A, but reduced, so that
# for every key you have a list of states if the key "STATES" exists
Ared = {k: A[k]["STATES"] for k in A if A[k].get("STATES")}
print(Ared)  # {'A': ['0', '1', '2'], 'B': ['10', '20'], 'C': ['100']}
# 2. get all the combinations
combs = list(itertools.product(*Ared.values()))
print(combs)  # [('0', '10', '100'), ('0', '20', '100'), ('1', '10', '100'), ('1', '20', '100'), ('2', '10', '100'), ('2', '20', '100')]
# 3. translate them into a nested dictionary
d = dict()
for comb in combs:
old_dict = d
for i, key in enumerate(comb):
if i == len(comb) - 1:
old_dict[key] = 0
elif not old_dict.get(key):
old_dict[key] = {}
old_dict = old_dict[key]

print(d)  # {'0': {'10': {'100': 0}, '20': {'100': 0}}, '1': {'10': {'100': 0}, '20': {'100': 0}}, '2': {'10': {'100': 0}, '20': {'100': 0}}}

Answer 2

你可以使用递归:

A = {'A':{'STATES':['0','1','2']}, 'B':{'STATES':['10','20']}}
def combos(d):
return 0 if not d else {i:combos(d[1:]) for i in d[0]}
print(combos([j['STATES'] for j in A.values()]))

输出:

{'0': {'10': 0, '20': 0}, '1': {'10': 0, '20': 0}, '2': {'10': 0, '20': 0}}

有两个以上的键:

A = {'A':{'STATES':['0','1','2']}, 'B':{'STATES':['10','20']}, 'C':{'STATES':['100']}}
print(combos([j['STATES'] for j in A.values()]))

输出:

{'0': {'10': {'100': 0}, '20': {'100': 0}}, '1': {'10': {'100': 0}, '20': {'100': 0}}, '2': {'10': {'100': 0}, '20': {'100': 0}}}