有没有办法获得3D矩阵的2D切片（嵌套列表）

Question

I'm have some data that is being stored in a 3x3x3 nested list and I want to get 2d layers form that list.

for example I want to do something like a[:, :,2], a[0,:,:] or a[:,1,:] on the following list:

a=[
[
    [(0, 0, 0), (0, 0, 1), (0, 0, 2)],
    [(0, 1, 0), (0, 1, 1), (0, 1, 2)],
    [(0, 2, 0), (0, 2, 1), (0, 2, 2)],
],
[
    [(1, 0, 0), (1, 0, 1), (1, 0, 2)],
    [(1, 1, 0), (1, 1, 1), (1, 1, 2)],
    [(1, 2, 0), (1, 2, 1), (1, 2, 2)],
],
[
    [(2, 0, 0), (2, 0, 1), (2, 0, 2)],
    [(2, 1, 0), (2, 1, 1), (2, 1, 2)],
    [(2, 2, 0), (2, 2, 1), (2, 2, 2)],
],]

to get:

[
[(0, 1, 0), (0, 1, 1), (0, 1, 2)],
[(1, 1, 0), (1, 1, 1), (1, 1, 2)],
[(2, 1, 0), (2, 1, 1), (2, 1, 2)],]

I tried that but doing a[:][1][:] does nothing to the list so I just get a[1] which looks like this:

[
[(1, 0, 0), (1, 0, 1), (1, 0, 2)],
[(1, 1, 0), (1, 1, 1), (1, 1, 2)],
[(1, 2, 0), (1, 2, 1), (1, 2, 2)],]

I don't think I can use numpy because I'm using jython which doesn't support libraries implemented in c.

Can you help me find a way to do it nicely (or find a library like numpy that works on jython)?

Answer 1

这将收集每个子矩阵的中间行：

[x[1] for x in a]