How to calculate all 24 rotations of 3d array?

Question

I have a 3d numpy array describing a polycube (imagine a 3d tetris piece). How can I calculate all 24 rotations?

Numpy\'s array manipulation routines includes a rot90 me

Answer 1

Look at the code for rot90. I see 3 variations on flip and swapaxes, depending on k the axis parameter.

fliplr(m).swapaxes(0, 1)
fliplr(flipud(m))
fliplr(m.swapaxes(0, 1))

fliplr(m) is just m[:, ::-1], and not surprisingly, flipud is m[::-1, ...].

You could flip the 3rd axis with m[:,:,::-1], or m[...,::-1].

np.transpose is another tool for permuting axes, that may, or may not, be easier to use than swapaxes.

If rot90 gives you 4 of the rotations, you should be able apply the same routines to produce the others. You just have to understand the logic underlying rot90.

e.g.

def flipbf(m):
    return m[:,:,::-1]

flipbf(m).swapaxes(0, 2)
flipbf(m).swapaxes(1, 2)
etc