How to assign a list variable to another without linking them?

Asked Dec 11 '21 at 06:27

Active Dec 11 '21 at 07:11

Viewed 19 times

So, I have a list variable (eg. var1) that is assigned to another list variable (eg. var2), when var2 changes var1 also changes.

Example:

movement = [3, 0]
projectile_movement = movement
projectile_movement[0] += 1
projectile_movement[1] += 1

What I am expecting to happen here, is the original movement variable should stay the same, as projectile_movement is the one being changed

However, the original movement variable is being changed along with projectile_movement

How can I stop this from happening?

edited Dec 11 '21 at 07:11

martineau

asked Dec 11 '21 at 06:27

`projectile_movement = movement.copy()` - creates a duplicate. – Larry the Llama Dec 11 '21 at 06:28
You will also frequently see `projectile_movement = movement[:]`. This is a Python idiom that uses slicing to copy an array. – Frank Yellin Dec 11 '21 at 06:58
Your variables are referring *to the same object*. This: `projectile_movement = movement` does not create a new list, it simply says "the name `projectile_movement` now refers to these same object as the object currently being referred to by `movement`. – juanpa.arrivillaga Dec 11 '21 at 07:20
Read the following: https://nedbatchelder.com/text/names.html – juanpa.arrivillaga Dec 11 '21 at 07:21

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