python nested list in dictionary

Mapping={}
Mapping[0.011].append("a")
print(Mapping)

---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
Input In [64], in <cell line: 2>()
1 Mapping={}
----> 2 Mapping[0.011].append("a")
3 print(Mapping)

KeyError: 0.011


expected output format
{0.011: [[list1],[list2 ],[ list3],.............[list n] ]}

有無方法

你個target係做乜？

=0.11 就return a?，定係加a

我睇漏左下面

https://www.geeksforgeeks.org/python-ways-to-create-a-dictionary-of-lists/amp/

照住做基本一樣

expected output
{0.011: [ ["a"],["a"],["a"], .................["a"] ]}
key is 0.011
value nested list [ ["a"],["a"],["a"], .................["a"] ]

Mapping={}
Mapping[0.011] = []
Mapping[0.011].append(["a"])

學好基本知識先

Mapping = {}
Mapping[0.01] = []
Mapping[0.01].append('a')
Mapping[0.01].append('b')
Mapping
{0.01: ['a', 'b']}

你想咁？
你要先定義0.01 對應list type (即係第二行)
另外建議返用String 做 Key, e.g. ‘0.01’

你都可以一開波就Set定，E.g.

Mapping = {0.01:[]}
Mapping[0.01].append(‘a’)

定係真係想做mapping to keys?

你段野有error

我邊行邊打冇試run,出左乜野error

係wor, 手機用啲網頁compiler 真伏

用deflautdict唔得咩

mapping=defaultdict(list)

thx 巴打們
問題已經解決左

段code 問題在於 未有條key, 就加value 入條key, 所以出error

我新寫法會加個if, 如果未有key, 就create
如果條key 已經 exist, append list into value