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 defaultdictimport jsonDist_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 intendedprint (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"

      ]

    }

  }

}