9.6. Cloning Lists¶
If we want to modify a list and also keep a copy of the original, we need to be able to make a copy of the list itself, not just the reference. This process is sometimes called cloning, to avoid the ambiguity of the word copy.
The easiest way to clone a list is to use the slice operator.
Taking any slice of a creates a new list. In this case the slice happens to
consist of the whole list.
Now we are free to make changes to b without worrying about a. Again, we can clearly see in
codelens that a and b are entirely different list objects.
Check your understanding
- [4,2,8,999,5,4,2,8,6,5]
- print alist not print blist
- [4,2,8,999,5]
- blist is changed, not alist.
- [4,2,8,6,5]
- Yes, alist was unchanged by the assignment statement. blist was a copy of the references in alist.
What is printed by the following statements?
alist = [4,2,8,6,5]
blist = alist * 2
blist[3] = 999
print(alist)
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