Every object's attribute update when I just want one

Question

When making objects of a certain class, I give them a matrix as an attribute and store these objects in a different class, however when I change this matrix for one object, it changes for every object

import numpy as np

class A:
    def __init__(self, matrix):
        self.matrix = matrix

class B:
    def __init__(self):
        self.objects = []
        matrix = np.matrix([
            [0,0,0],
            [0,0,0],
            [0,0,0]
        ])
        for i in range(10):
            newObject = A(matrix)
            self.objects.append(newObject)

objectB = B()
objectB.objects[0].matrix[0] = [1,1,1] # change top row of first object to 1,1,1
for object in objectB.objects:
    print(object.matrix)

The code above prints 10 matrices all with [1,1,1] as the top row but should just print the first matrix with [1,1,1] on the top row and the other 9 matrices with all zeros

Answer 1

Simply use the copy function when creating the matrix attribute in class A

self.matrix = matrix.copy()

This makes a unique matrix for each object instead of referencing the same matrix.