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I am working on a sudoku solver and I ran into a problem with classes. I still am not familiar with the mechanics of a class so I did this project to help me.

Is there a way for the class to not affect the original list? As shown in the example code, I wanted to change the first element of the list of lists to 11 but only for the mat1 and not the num_matrix.

Thank you so much in advance!

from pprint import pprint

num_matrix = [
    [0, 0, 9,   4, 0, 7,   0, 0, 1],
    [0, 0, 0,   0, 3, 0,   0, 7, 0],
    [4, 0, 0,   0, 8, 0,   0, 0, 0],

    [5, 0, 0,   1, 0, 4,   0, 2, 0],
    [0, 0, 3,   0, 0, 0,   5, 0, 0],
    [0, 0, 0,   8, 0, 0,   0, 0, 0],

    [3, 0, 0,   5, 0, 2,   0, 1, 0],
    [0, 0, 0,   0, 7, 0,   0, 0, 0],
    [0, 6, 0,   0, 0, 0,   0, 0, 9]]


class hi():
    def __init__(self, puzzle):
        self.puzzle = puzzle
        
    def replace(self):
        self.puzzle[0][0] = 11

mat1 = hi(num_matrix)
mat1.replace()

pprint(num_matrix)
pprint(mat1.puzzle)

and here is the output:

[[11, 0, 9, 4, 0, 7, 0, 0, 1],
 [0, 0, 0, 0, 3, 0, 0, 7, 0],
 [4, 0, 0, 0, 8, 0, 0, 0, 0],
 [5, 0, 0, 1, 0, 4, 0, 2, 0],
 [0, 0, 3, 0, 0, 0, 5, 0, 0],
 [0, 0, 0, 8, 0, 0, 0, 0, 0],
 [3, 0, 0, 5, 0, 2, 0, 1, 0],
 [0, 0, 0, 0, 7, 0, 0, 0, 0],
 [0, 6, 0, 0, 0, 0, 0, 0, 9]]
[[11, 0, 9, 4, 0, 7, 0, 0, 1],
 [0, 0, 0, 0, 3, 0, 0, 7, 0],
 [4, 0, 0, 0, 8, 0, 0, 0, 0],
 [5, 0, 0, 1, 0, 4, 0, 2, 0],
 [0, 0, 3, 0, 0, 0, 5, 0, 0],
 [0, 0, 0, 8, 0, 0, 0, 0, 0],
 [3, 0, 0, 5, 0, 2, 0, 1, 0],
 [0, 0, 0, 0, 7, 0, 0, 0, 0],
 [0, 6, 0, 0, 0, 0, 0, 0, 9]]

here is my desired output:

[[0, 0, 9, 4, 0, 7, 0, 0, 1],
 [0, 0, 0, 0, 3, 0, 0, 7, 0],
 [4, 0, 0, 0, 8, 0, 0, 0, 0],
 [5, 0, 0, 1, 0, 4, 0, 2, 0],
 [0, 0, 3, 0, 0, 0, 5, 0, 0],
 [0, 0, 0, 8, 0, 0, 0, 0, 0],
 [3, 0, 0, 5, 0, 2, 0, 1, 0],
 [0, 0, 0, 0, 7, 0, 0, 0, 0],
 [0, 6, 0, 0, 0, 0, 0, 0, 9]]
[[11, 0, 9, 4, 0, 7, 0, 0, 1],
 [0, 0, 0, 0, 3, 0, 0, 7, 0],
 [4, 0, 0, 0, 8, 0, 0, 0, 0],
 [5, 0, 0, 1, 0, 4, 0, 2, 0],
 [0, 0, 3, 0, 0, 0, 5, 0, 0],
 [0, 0, 0, 8, 0, 0, 0, 0, 0],
 [3, 0, 0, 5, 0, 2, 0, 1, 0],
 [0, 0, 0, 0, 7, 0, 0, 0, 0],
 [0, 6, 0, 0, 0, 0, 0, 0, 9]]
Risal Shahid
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    Instead of `self.puzzle = puzzle`, maybe `self.puzzle = copy.deepcopy(puzzle)`? – j1-lee Nov 01 '21 at 07:45
  • Does this answer your question? [List changes unexpectedly after assignment. Why is this and how can I prevent it?](https://stackoverflow.com/questions/2612802/list-changes-unexpectedly-after-assignment-why-is-this-and-how-can-i-prevent-it) – Passerby Nov 01 '21 at 07:45

0 Answers0