Solved by ptrblck in post #2 
              
              
                If you are storing the filenames in e.g. a list in the initially posted order, then you are correct in the batch outputs. 
If you are not using shuffle=True, the Dataset.__getitem__ will get indices in a sequential order (i.e. 0, 1, 2, 3, ...) and depending how you are storing and loading the data, …