Python初学者如何从列表中回忆已删除的项目

Question

我是一个python初学者，我想知道一旦列表中的项目被替换，它能被召回吗

Friends=["Jen","Lam","Sam","Song"]
print (Friends)

#replace a list item 
Friends[0] = "Ken"
print (Friends)

如果我想说python中的Jen被Ken替换了，那么我应该如何写这行代码，而不是直接写出print("Jen")并使用变量

Answer 1

据我所知没有。但是你可以复制一份列表，然后用它从列表中获取旧名称，从而将其更改回原来的状态

Friends=["Jen","Lam","Sam","Song"]
replaceName = Friends[0]
newName= "ken"
Friends [0] = newName

print(replaceName, " was replaced by ", newName)
print(Friends)

Answer 2

在更换Friends[0]之前，请跟踪它

即

friends=["Jen","Lam","Sam","Song"]
print(Friends)
replaced = friends[0]
friends[0] = "Ken"
print(replaced + " was replaced by " + friends[0])

您还可以使用pop和insert

friends=["Jen","Lam","Sam","Song"]
print(friends)
replaced = friends.pop(0)
friends.insert(0, "Ken")
print(replaced + " was replaced by " + friends[0])