列表在附加變量更改后更新自身

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]]]

當我只在“數據”變量中附加數據時，為什么我的“mainData”會發生變化？

Answer 1

因為它也復制索引； 下面的代碼是 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)

希望能幫助到你...