Numpy Array Change indices
There are two ways to archive this either np.reshape(x, ndims) or np.transpose(x, dims). 
For pictures I propose np.transpose(x, dims) which can be applied using 
X_train = np.transpose(X_train, (3,0,1,2)).
I have an numpy-array with 32 x 32 x 3 pictures with X_train.shape: (32, 32, 3, 73257). However, I would like to have the following array-shape: (73257, 32, 32, 3). 
How can I accomplish this?