如何动态地初始化嵌套字典并为其赋值

Question

我正在尝试动态启动Python中的嵌套字典并为其赋值，到目前为止我还没有成功，请帮助我，谢谢。 这就是我所尝试的

thelist = [
['2023', 'John Professa', 'Mfangano', '10 E', '84 A', '84 A', '3 E', '53 C', '65 B', '84 A', '84 A', '84 A', '84 A', '84 A', '400', 464, '66', '64', 'B', '1'],
['33332', 'd dd', 'Mfangano', '40 D+', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '403', 40, '6', '4', 'E', '5'],
['3333', 'Isaac ', 'Mfangano', '83 A', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '402', 83, '12', '12', 'D-', '2'],
['1234', 'asdfas f', 'Mfangano', '60 B-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '390', 60, '9', '8', 'E', '4'],
['7777', 'asdfas f', 'Kujeni', '66 B', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '280', 66, '9', '9', 'E', '3'],
]

nested_Dictionary = {}

main_dorms = ['kujeni', 'Mfangano', 'Bakini', 'Kujeni', 'Flamingo']

for value in main_dorms:
    nested_Dictionary[f'{value}'] = {}
    nested_Dictionary[f'{value}']['A'] = [1]
    nested_Dictionary[f'{value}']['A-'] = [1]
    nested_Dictionary[f'{value}']['B+'] = [1]
    nested_Dictionary[f'{value}']['B-'] = [1]
    nested_Dictionary[f'{value}']['C+'] = [1]
    nested_Dictionary[f'{value}']['C'] = [1]
    nested_Dictionary[f'{value}']['C-'] = [1]
    nested_Dictionary[f'{value}']['D+'] = [1]
    nested_Dictionary[f'{value}']['D'] = [1]
    nested_Dictionary[f'{value}']['D-'] = [1]
    nested_Dictionary[f'{value}']['E'] = [1]
    nested_Dictionary[f'{value}']['mean'] = [1]
    nested_Dictionary[f'{value}']['meangrade'] = [1]

print(nested_Dictionary)

for value in thelist:
    idnumber = value[0]
    stream = value[2]
    meangrade = value[18]
    meanmarks = value[17]

    print(idnumber, stream, meangrade, meanmarks)
    nested_Dictionary[f'{stream}'][meangrade].append(meangrade)
    nested_Dictionary[f'{stream}']['mean'].append(meanmarks)
    nested_Dictionary[f'{stream}']['meangrade'].append(meanmarks)

print(nested_Dictionary)

这给了我一个关键错误

 nested_Dictionary[f'{stream}'][meangrade].append(meangrade)
KeyError: 'Mfangano'

Answer 1

添加到for循环中：

nested_Dictionary[f'{value}']['B'] = [1]

Answer 2

在meangrade周围添加引号，当我添加此代码时，您的代码工作正常

 nested_Dictionary[f'{stream}']['meangrade'].append(meangrade)

Answer 3

您应该使用能够动态构建锯齿形字典的东西来重新处理此问题-它将具有更大的可扩展性。我首选的实现方式是：

>>> from collections import defaultdict
>>> 
>>> def defaulter():
...   return defaultdict(defaulter)
... 
>>> nested = defaultdict(defaulter)
>>> nested['a'][1]['c'][None] = True
>>> nested
defaultdict(<function defaulter at 0x7ffb8ba6db80>, {'a': defaultdict(<function defaulter at 0x7ffb8ba6db80>, {1: defaultdict(<function defaulter at 0x7ffb8ba6db80>, {'c': defaultdict(<function defaulter at 0x7ffb8ba6db80>, {None: True})})})})

在分配时，您永远不会遇到键错误。需要注意的是，在访问缺少的值时，无论嵌套方式如何，您也不会遇到keyrerrors，并且它会在树下生成空的defaultdict：

>>> nested['missing']
defaultdict(<function defaulter at 0x7ffb8ba6db80>, {})