combine multiple numpy ndarrays as list - arrays

Question

I have three equally dimensioned numpy arrays.
I would like to store the data from all three in an array of the same dimensions and size.
To do this, I would like to store three bytes of information per item in the array. I assume this would be a list.
e.g.
>>>red = np.array([[150,25],[37,214]])
>>>green = np.array([[190,27],[123,231]])
>>>blue = np.array([[10,112],[123,119]])
insert combination magic to make a combined array called RGB
>>>RGB
array([(150,190,10),(25,27,112)],[(37,123,123),(214,231,119)])

Answer 1

For a start, each is 2x2. Combined in a list with array, same construction as in making red, produces a 3x2x2.
In [344]: red = np.array([[150,25],[37,214]])
In [345]: green = np.array([[190,27],[123,231]])
In [346]: blue = np.array([[10,112],[123,119]])
In [347]: np.array([red,green,blue])
Out[347]:
array([[[150, 25],
[ 37, 214]],
[[190, 27],
[123, 231]],
[[ 10, 112],
[123, 119]]])
In [348]: _.shape
Out[348]: (3, 2, 2)
That's not the order you want, but we can easily reshape, and if needed transpose.
The target, with an added set of []
In [350]: np.array([[(150,190,10),(25,27,112)],[(37,123,123),(214,231,119)]])
Out[350]:
array([[[150, 190, 10],
[ 25, 27, 112]],
[[ 37, 123, 123],
[214, 231, 119]]])
In [351]: _.shape
Out[351]: (2, 2, 3)
so try moving the 3 shape to the end with transpose:
In [352]: np.array([red,green,blue]).transpose(1,2,0)
Out[352]:
array([[[150, 190, 10],
[ 25, 27, 112]],
[[ 37, 123, 123],
[214, 231, 119]]])
===========================
I should have suggested stack. This a newish version of concatenate that lets us join arrays on different new dimensions. With axis=0 it behaves like np.array. But to join on the last, to put the rgb dimension last use:
In [467]: np.stack((red,green,blue),axis=-1)
Out[467]:
array([[[150, 190, 10],
[ 25, 27, 112]],
[[ 37, 123, 123],
[214, 231, 119]]])
In [468]: _.shape
Out[468]: (2, 2, 3)
Note that this expression does not assume anything about the shape of red, etc, except that they are equal. So it will work with 3d arrays as well.