How are matrices assigned?

Question

Python

An A-matrix in python, an empty
B-matrix in python, with data I
assign A=B,
I start changing the data in A and the data in B changes, what should I do to prevent this from happening and why does this happen?

Answer 1

Why is this happening?

Because:

a = [1,2,3,5,6]
b = a
print(id(a))
print(id(b))
# 1552394418184
# 1552394418184

both A and B refer after assignment to the same object.

what to do to prevent this from happening

b = a.copy()
print(id(a))
print(id(b))
# 1552394980744
# 1552395031496

now they are two different objects

Answer 2

import copy

b = copy.deepcopy(a)