如何用列表中的每個字典的元組替換字典值

Question

錯誤“元組”對象沒有屬性“項目”

當我試圖在最后一行代碼中替換字典值時，但不在循環中它起作用（3 行代碼）。

dictionary = { "a" : "100", "b" : "200", "c" : {"a":"f","b":"4"} }
D = [dictionary for i in range(10)]
#dictionary["c"] = tuple(dictionary["c"].items()) # it works
for i in D:
    i["c"] = tuple(i["c"].items()) # does not work

Answer 1

這不起作用，因為當你這樣做時：

D = [dictionary for i in range(10)]

您創建了一個列表，其中包含對同一對象的 10 個引用。 一旦第一次迭代成功：

i['c'] = tuple(i['c'].items())

下一個肯定會失敗，因為它與您在上一次迭代中處理的對象相同，因此'c'值是一個tuple ！

筆記：

In [10]: dictionary = { "a" : "100", "b" : "200", "c" : {"a":"f","b":"4"} }
    ...: D = [dictionary for i in range(10)]
    ...: print([hex(id(x)) for x in D])
    ...:
['0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088', '0x105c59088']

相反，請執行以下操作：

In [11]: dictionary = { "a" : "100", "b" : "200", "c" : {"a":"f","b":"4"} }
    ...: D = [dictionary.copy() for i in range(10)]
    ...: print([hex(id(x)) for x in D])
    ...:
['0x105c592c8', '0x105c59e48', '0x105cfd848', '0x105c9af48', '0x105d06c48', '0x105c59708', '0x105d06cc8', '0x105c59488', '0x105c59e08', '0x105c593c8']

現在它將起作用：

In [12]: for i in D:
    ...:     i['c'] = tuple(i['c'].items())
    ...:

In [13]: D
Out[13]:
[{'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))},
 {'a': '100', 'b': '200', 'c': (('b', '4'), ('a', 'f'))}]