How to Correctly mask 3D Array with numpy

Question

I\'m trying to mask a 3D array (RGB image) with numpy.

However, my current approach is reshaping the masked array (output below). I have tried to follow the approach

Answer 1

After finding the following post on loss of dimensions HERE, I have found a solution using numpy.where:

masked_array = np.where(mask==1, a , 0)

This appears to work well.