如何避免在嵌套字典中添加重复值？

Question

我有一个复杂的嵌套字典 - 但我已将我的问题简化为这个玩具示例。添加一个值会跨多个字典这样做，这不是故意的：

from collections import defaultdict

import json

Dist_T = defaultdict(lambda:([]))

Filter_T = defaultdict(lambda:Dist_T)

Phase_T = defaultdict(lambda:Filter_T)

    

Phase_T[60]['Green'][4].append('here')

Phase_T[60]['Green'][4].append('there')

Phase_T[60]['Blue'][4].append('over_there') #"over-there" will also be appended to the

                                            # list for the dictionary of the

                                            # Green key which is not intended

print (json.dumps(Phase_T, indent=2))

输出是：

{ "60": { "Green": { "4": [ "here", "there", "over_there" ] }, "Blue": { "4": [ "here", "there", "over_there" ] } } }

想要的是：

{ "60": { "Green": { "4": [ "here", "there"] }, "Blue": { "4": [ "over_there" ] } } }

Answer 1

Phase_T你应该在一行中声明：Phase_T = defaultdict(lambda: defaultdict(lambda: defaultdict(list)))Phase_T[60]['Green'][4].append('here')Phase_T[60]['Green'][4].append('there')Phase_T[60]['Blue'][4].append('over_there')print (json.dumps(Phase_T, indent=2))这打印：{  "60": {    "Green": {      "4": [        "here",        "there"      ]    },    "Blue": {      "4": [        "over_there"      ]    }  }}