列表在附加变量更改后更新自身

Question

mainData = []
data = []
newEntry = [1,2,3]
data.append(newEntry)
mainData.append(data)
print(mainData)
anotherEntry = [4,5,6]
data.append(anotherEntry)
thirdEntry = [7,8,9]
data.append(thirdEntry)
print(mainData)

OP =>
[[[1, 2, 3]]]
[[[1, 2, 3], [4, 5, 6], [7, 8, 9]]]

当我只在“数据”变量中附加数据时，为什么我的“mainData”会发生变化？

Answer 1

因为它也复制索引； 下面的代码是 go 的方式；

mainData = []
data = []
newEntry = [1,2,3]
data.append(newEntry)
mainData.append(data.copy()) # change here
print(mainData)
anotherEntry = [4,5,6]
data.append(anotherEntry)
thirdEntry = [7,8,9]
data.append(thirdEntry)
print(mainData)

希望能帮助到你...