Difference between tensor x[:,:,index] and x[:,:,index,:]

Hello. Given a tensor x with shape (1,400,6,1), what is the difference between x[:,:,index] and x[:,:,index,:]? They both seem to give me an output with the desired shape (1, 400, 1).

There is no difference since you can skip the trailing : while indexing.

All right. Thank you.