英文:
Add dictionary in List in Python but, data is duplicated
问题
data = []
dic = dict.fromkeys(['a', 'b', 'c'], 0)
value = 1
for i in range(3):
key = list(dic.keys())
for j in range(len(dic)):
dic[key[j]] = value
value += 1
data.append(dic)
for i in data:
print(i)
在这段代码中，我期望的结果是这样的：
{'a': 1, 'b': 2, 'c': 3}
{'a': 4, 'b': 5, 'c': 6}
{'a': 7, 'b': 8, 'c': 9}
但实际结果是：
{'a': 7, 'b': 8, 'c': 9}
{'a': 7, 'b': 8, 'c': 9}
{'a': 7, 'b': 8, 'c': 9}
要修复这段代码以获得期望的结果，你可以在循环内部创建新的字典，而不是多次使用同一个字典。以下是修复后的代码：
data = []
for i in range(1, 10, 3):
dic = {'a': i, 'b': i + 1, 'c': i + 2}
data.append(dic)
for i in data:
print(i)
这将产生期望的输出：
{'a': 1, 'b': 2, 'c': 3}
{'a': 4, 'b': 5, 'c': 6}
{'a': 7, 'b': 8, 'c': 9}
英文:
data = []
dic = dict.fromkeys(['a', 'b', 'c'], 0)
value = 1
for i in range(3):
key = list(dic.keys())
for j in range(len(dic)):
dic[key[j]] = value
value += 1
data.append(dic)
for i in data:
print(i)
In this code, I expexted like this.
{1, 2, 3}
{4, 5, 6}
{7, 8, 9}
but the result is
{7, 8, 9}
{7, 8, 9}
{7, 8, 9}
How can i fix this code to get result that i expected?
答案1
得分: 1
你只有一个字典，dic。你已经创建了一个包含对它的三个引用的列表。为了获得你想要的结果，更改你的代码，使其在主循环的每次迭代中创建一个新的字典。
英文:
You only have one dictionary, dic. You have created a list with three references to it. To get the results you want, change your code to create a new dictionary for each iteration of the main loop
答案2
得分: 0
使用：
data.append(dic.copy())
这将创建一个新的对象，而不是将对 dic 的引用添加到您的列表中。
英文:
Instead of :
data.append(dic)
Use:
data.append(dic.copy())
This will create a new object, instead of adding a reference to dic to your list.
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