在 numpy 数组 python 中交换 2 个术语

Question

import numpy as np

old_order=np.array([0,1,2,3,4,5,6,7,8])
new_order=old_order
swap_1,swap_2=random.sample(range(0,9),2)
new_order[swap_1],new_order[swap_2]=old_order[swap_2],old_order[swap_1]

print(old_order,new_order)

So I am trying to swap two random element within an array. old_order would be the original array and new_order would be the array after the switch happened. What I don't understand is that why would the values of the old_order be changed

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I have narrow down the problem to

new_order[swap_1],new_order[swap_2]=old_order[swap_2],old_order[swap_1]

If this line is remove, both new order and old order will be the same.

Answer 1

There is only one array. old_order and new_order are both bound to the same array. This line

new_array = old_array

makes a new reference. It doesn't make a copy of the data. If you really need a copy, use old_order.copy() .

Answer 2

new_order=old_order.copy()

Create a new array for new_order. Otherwise new_order, old_order take the same memory.