Python:在嵌套字典中为一个键附加多个值

Question

我有下面的元组列表:

p = [("01","Master"),("02","Node"),("03","Node"),("04","Server")]

我希望我的输出看起来像:

y = {
     "Master":{"number":["01"]},
     "Node":{"number":["02", "03"]},
     "Server":{"number":["04"]}
     }

我试过下面的代码:

y = {}
for line in p:
     if line[1] in y:
          y[line[1]] = {}
          y[line[1]]["number"].append(line[0])
     else:
          y[line[1]] = {}
          y[line[1]]["number"] = [line[0]]

我得到以下错误:

 Traceback (most recent call last):
         File "<stdin>", line 4, in <module>
 KeyError: 'number'

我该如何解决？

Answer 1

from collections import defaultdict

d = defaultdict(lambda: defaultdict(list))
for v, k in p:
    d[k]["number"].append(v)


print(d)

  defaultdict(<function <lambda> at 0x7f8005097578>, {'Node': defaultdict(<type 'list'>, {'number': ['02', '03']}), 'Master': defaultdict(<type 'list'>, {'number': ['01']}), 'Server': defaultdict(<type 'list'>, {'number': ['04']})})

没有默认字典:

d = {}
from pprint import pprint as pp
for v, k in p:
    d.setdefault(k,{"number":[]})
    d[k]["number"].append(v)


pp(d)

{'Master': {'number': ['01']},
 'Node': {'number': ['02', '03']},
 'Server': {'number': ['04']}}