Why are variables entangled?

Question

a=[1,2,3]
b=a
b.append(4)
Print(a)
Why does a now = b? This confuses me, if i had an apple and cloned it. Took a bite of the clone the original wouldnt have a bite in it. Can someone please explain?

Answer 1

The names for variables in Python are like name stickers.

a = [1, 2, 3]

This means: 'Please give me this list, and let me call it a.'

b = a

This means: 'Please give me a and let me call it b.'

It is the same list, you just have added a second sticker to it.

If you want to clone the list, you need to create a *new* list that looks like the old one. For example like this:

b = list(a)

This means: 'Give me a list with the values from a and let me call it b.'