创建两个零列表的列表

Question

I'm trying to create a list of two lists of zeros for 20 times, like this:

[[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0],[0][0]]

I tried this:

output = []
for j in range(20) :
    output.append([0])

I which it gives me:

[[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0],[0]]

But this is not what I want:(

Any help, please?

Answer 1

Having a list like [[0][0], [0][0]] is not a valid syntax in Python, but you can have something like this: [[0, 0]] by doing the following.

zeros_list = [[0, 0] for _ in range(20)]

output

[[0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0]]

Or you can have something like this [[[0], [0]], [[0], [0]]] , which would be a list of lists of lists containing zeros by doing:

zeros_list = [[[0], [0]] for _ in range(20)]

Answer 2

Another way:

result = [[0, 0]] * 20
print (result)
#[[0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0]]

result = [[[0], [0]]] * 20
print (result)
#[[[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]], [[0], [0]]]