[SOLVED] Same input different output

[antarling]

What's the reason?

def f(a, n):
	for i in range(n):
		   a[i][n // 2] = '*'
		   a[n // 2][i] = '*'
		   a[i][i] = '*'
		   a[i][n - i - 1] = '*'
	return '\n'.join([' '.join(i) for i in a])

n = 9
a = [['.'] * n for i in range(n)]
b = [['.'] * n] * n
print(a == b, '\n')
print(f(a, n), '\n')
print(f(b, n), '\n')
print(f(a, n) == f(b, n))

Output:

True

* . . . * . . . *
. * . . * . . * .
. . * . * . * . .
. . . * * * . . .
* * * * * * * * *
. . . * * * . . .
. . * . * . * . .
. * . . * . . * .
* . . . * . . . *

* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *
* * * * * * * * *

False

[deanhystad]

Not the same input. a may equal b, but it is completely different. a contains n different lists. b contains n references to the same list.

[antarling]

Not the same input. a may equal b, but it is completely different. a contains n different lists. b contains n references to the same list.

Thank you, i didn't expect that same looking lists can be different