Flip 3D numpy Array

Question

I need to flip 3D Array A shaped [m, n, k], along the Z axis. I need plane 0 (A[0,:,:]) to become k-1, plane 1 become k-2 plane and so on.

I need to do that on many array's, and loops are very slow.

I tried:

C = numpy.rot90(A,2)
C = flipud(A)
C = A[::-1]

I tried also rol and reshape, not what I needed.

For example: A is (3, 2, 2)

    A= np.array([[[ 1.01551435, -0.76494131],
 [ 0.56853752 , 1.94491724]],
[[-0.97433012 , 2.08134198],
 [-1.34997602 ,-0.33543117]],
[[ 0.54217072, -1.33470658],
 [-0.50179028, -0.66593918]]])

I need to reorder Z axis upside down:

[[ 0.54217072 -1.33470658]
 [-0.50179028 -0.66593918]]
[[-0.7703279   0.02402204]
 [-0.18006451 -0.37589744]]
[[ 1.01551435 -0.76494131]
 [ 0.56853752  1.94491724]]

Any ideas ?

Give a small example, say a 2x3x4 array, and what you want. Also indicate what is wrong with what you tried. I'm guessing A[:, :, ::-1] will do the trick. — hpaulj
– hpaulj, Commented Sep 6, 2016 at 21:19
@hpaulj 's suggestion is a good one try... a = np.arange(2*3*4).reshape(2,3,4) then use his rearrangement to make it clear if this is what you want. — user1121588
– user1121588, Commented Sep 6, 2016 at 21:49

Naomi Fridman · Accepted Answer · 2018-03-20 13:45:02Z

3

As @hpaulj suggested:

A = A[::-1, :, :]

print A.shape
print A

    (3L, 2L, 2L)

[[[ 0.54217072 -1.33470658]
  [-0.50179028 -0.66593918]]

 [[-0.97433012  2.08134198]
  [-1.34997602 -0.33543117]]

 [[ 1.01551435 -0.76494131]
  [ 0.56853752  1.94491724]]]

answered Mar 20, 2018 at 13:45

Naomi Fridman

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