matrix = [[[]]*3]*3
for i in range(3):
for j in range(3):
matrix[i][j] = random.randint(10,100)
How is it filled in:
0 i
0 j
[[98, [], []], [98, [], []], [98, [], []]] matrix
[98, [], []] i=0
1 j
[[98, 80, []], [98, 80, []], [98, 80, []]] matrix
[98, 80, []] i=0
2 j
[[98, 80, 52], [98, 80, 52], [98, 80, 52]] matrix
[98, 80, 52] i=0
1 i
0 j
[[61, 80, 52], [61, 80, 52], [61, 80, 52]] matrix
[61, 80, 52] i=1
1 j
[[61, 70, 52], [61, 70, 52], [61, 70, 52]] matrix
[61, 70, 52] i=1
2 j
[[61, 70, 24], [61, 70, 24], [61, 70, 24]] matrix
[61, 70, 24] i=1
2 i
0 j
[[22, 70, 24], [22, 70, 24], [22, 70, 24]] matrix
[22, 70, 24] i=2
1 j
[[22, 50, 24], [22, 50, 24], [22, 50, 24]] matrix
[22, 50, 24] i=2
2 j
[[22, 50, 72], [22, 50, 72], [22, 50, 72]] matrix
[22, 50, 72] i=2
I've been getting to know Python for a week now and would like an explanation. I expected that each nested list would be filled in separately, but I may not understand some nuances or do not see a problem.
As I see it: The iteration between cycles goes as intended, and the appeal through the indexing operator should go as it should, that is, list[0][0] 1 element of the base list, which is a nested list in which I already refer to its 1 element. But the appeal occurs to all 1 elements of nested lists at once.
I made an option where I bypassed this problem by reading about the 3-dimensional array text
def matrix_generator(i,j):
'''
Generates a matrix
Matrix generator(i,j) with random values
'''
#Local variables
matrix = [[[]]*j]*i
matrix_dublicate = [[]]*i
for row in range(i):
for column in range(j):
matrix[row][column] = random.randint(10,100)
#Creating a duplicate
else:
matrix_dublicate[row] = matrix[row].copy()
#Duplicate implementation
for i in range(len(matrix)):
matrix[i] = matrix_dublicate[i]
return matrix
But I believe I have not solved this problem. In this regard, is there a cleaner way to solve this problem? And I would like to read about how and why this problem occurs at all?
