[Python] Using a class with numpy does not work correctly

I define an array of 4 corners

import numpy as np

class Corner():
centres = np.zeros((3,2))
id=0

corners=np.empty((4)).astype(Corner)

for i in range(4):
corner=Corner()
corner.id = i
corners=corner


The corners each contain an np.array called centres When I attempt to change just one entry for corners[1].centres ...

corners[1].centres[0]=[5,5]


... I find that all the other corners get updated as well.

Things work well if I just use numpy:

corners=np.zeros((4,3,2))

def show(corners):
for i in range(4):
print("[",end="")
for j in range(3):
print(corners[j],end="")
print("] ")
print()

show(corners)
print("set corners[1][0]=[5,5]...")
corners[1][0]=[5,5]
show(corners)

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