Structure of target values y

Hello! I have a question about the structure of the target values y that are going into the training of a model with tensorflow which is discussed in the video “Building a neural network”. The structure in this case of y is a 1D numpy array. What is the logic behind it? Would it not make more sense to have it in a e.g. 4x1 matrix?
thank you very much in advance and best regards

Either method could work.

You should try both methods while practicing implementations