Why elements of a 2D array are linked

Question

I am taking a quick course Python programming and I learn a quick way to initialize an array in Python by using the * operator. I am trying to extend it to a 2d case.

A = [[0]*3]*3

I then try to modify the [0][1] element to specific value but I found that all elements on the middle column are changed at the same time. For example,

A[0][1] = 888

It results in A[0][1] = 888, A[1][1] = 888, A[2][1] = 888. I really don't see how this happens. It seems like that all elements are linked and refer to the same address. But if I change the initialization code to

A = [[0,0,0],[0,0,0],[0,0,0]]

The problem is gone. I just wonder what is wrong with the first approach. Any fast way to initialize the array with certain value but without explicitly specify the elements?

Thanks. I will close my question – user1285419 Jan 17 '20 at 20:40 — user1285419, Jan 17 '20 at 20:40
try to do it with list comprehension – Mohsen_Fatemi Jan 17 '20 at 20:42 — Mohsen_Fatemi, Jan 17 '20 at 20:42

score 0 · Answer 1 · answered Jan 17 '20 at 20:43

0

You could try this:

a = [[0 for i in range(3)] for o in range(3)]

answered Jan 17 '20 at 20:43

Unicone

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Why elements of a 2D array are linked

1 Answers1