Suduko

grid.py

def __generate_grid(self):
        import random
        self.__needs_update = True
        self.__grid = [[None for i in range(9)] for j in range(9)]
        nums = [i for i in range(1, 10)]
        random.shuffle(nums)
        
        for x in range(3):
            template_row = [self.__grid[(x * 3) - 1][(1 + i) % 9] for i in range(9)] if x != 0 else nums
            for i in range(3):
                row = i + x * 3
                for j in range(9):
                    self.__grid[row][j] = template_row[(j + i * 3) % 9]

        rows1, rows2, rows3 = [0, 1, 2], [3, 4, 5], [6, 7, 8]
        random.shuffle(rows1)
        random.shuffle(rows2)
        random.shuffle(rows3)
        row_new_indices = []
        row_new_indices.extend(rows1)
        row_new_indices.extend(rows2)
        row_new_indices.extend(rows3)
        
        temp = self.__grid.copy()
        print(f'BEFORE TRANSFORMATION:-\n{self}\n\n\n')
        for i in range(9):
            self.__grid[i] = temp[row_new_indices[i]]
            for j in range(9):
                if random.randint(1, 10) > 4:
                    self.__grid[i][j] = None