I am trying to multiply some matrices in python, using the np.dot function.I have a three by three array that I want to multiply by a three by one
ValueError: shapes (3,3,1) and (3,1) not aligned: 1 (dim 2) != 3 (dim 0)
What exactly does the third dimension on the array mean? Is there a way to get rid of it?
A (3,3,1) means that you have a vector of 3 two dimensional vectors. Take this as example:
a = np.random.rand(3,3,1)
print(a)
[[[0.08233029]
[0.21532053]
[0.88495997]]
[[0.59743708]
[0.97966668]
[0.44927175]]
[[0.40792714]
[0.85891152]
[0.22584841]]]
As above, there are 3 vectors of two dimensions with 3 numbers in a vector. In order to remove it, just use np.reshape to do the trick.
a = np.reshape(a, [3,3])
print(a)
[[0.08233029 0.21532053 0.88495997]
[0.59743708 0.97966668 0.44927175]
[0.40792714 0.85891152 0.22584841]]
From here onwards, you can do your np.dot to obtain your result