I understand that through Sort N-D numpy array by another 1-D array the use of fancy indexing, I can do the following c = a[:, :, b]
with b
defining the order to which I want to sort by column
>>> a = np.array([[[ 0, 1], [ 2, 3]],
[[ 4, 5], [ 6, 7]],
[[ 8, 9], [10, 11]]])
>>> b = np.array([1, 0])
>>> c = a[:, :, b]
>>> c
array([[[ 1, 0],
[ 3, 2]],
[[ 5, 4],
[ 7, 6]],
[[ 9, 8],
[11, 10]]])
Now I increase b
with 2 more inputs to b2
corresponding to how I want to sort each set of 2x2 in a
>>> b2 = np.array([[1, 0], [0, 1], [1, 0]])
>>> c2 = ?
>>> c2
array([[[ 1, 0],
[ 3, 2]],
[[ 4, 5],
[ 6, 7]],
[[ 9, 8],
[11, 10]]])
I have a larger set of inputs and I have a function that returns an array similar to 'b2' which provides me the info to which I should obtain. Hence may I know what should I filling into the c2 = ?
in order to get the desired result?
Here's one approach with fancy-indexing -
(a[np.arange(a.shape[0])[:,None],:,b2]).transpose(0,2,1)
Sample run -
In [191]: a
Out[191]:
array([[[7, 8, 5, 2, 0],
[6, 7, 0, 7, 1],
[7, 6, 5, 4, 0]],
[[8, 0, 5, 5, 7],
[4, 3, 4, 0, 1],
[8, 6, 3, 2, 4]],
[[3, 2, 7, 3, 7],
[4, 3, 0, 1, 5],
[4, 3, 7, 8, 7]]])
In [192]: b2
Out[192]:
array([[1, 2, 4, 3, 0],
[4, 2, 0, 1, 3],
[1, 3, 4, 0, 2]])
In [193]: (a[np.arange(a.shape[0])[:,None],:,b2]).transpose(0,2,1)
Out[193]:
array([[[8, 5, 0, 2, 7],
[7, 0, 1, 7, 6],
[6, 5, 0, 4, 7]],
[[7, 5, 8, 0, 5],
[1, 4, 4, 3, 0],
[4, 3, 8, 6, 2]],
[[2, 3, 7, 3, 7],
[3, 1, 5, 4, 0],
[3, 8, 7, 4, 7]]])
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