lists in python, with references [duplicate]

Question

How do I copy the contents of a list and not just a reference to the list in Python?

Answer 1

Look at the copy module, and notice the difference between shallow and deep copies:

The difference between shallow and deep copying is only relevant for compound objects (objects that contain other objects, like lists or class instances):

• A shallow copy constructs a new compound object and then (to the extent possible) inserts references into it to the objects found in the original.

• A deep copy constructs a new compound object and then, recursively, inserts copies into it of the objects found in the original.

Answer 2

Use a slice notation.

newlist = oldlist

This will assign a second name to the same list

newlist = oldlist[:]

This will duplicate each element of oldlist into a complete new list called newlist