Should I report loss on the last batch or the entire training dataset?

Question

In the training loop below, you can see that train_loss represents the loss on the most recent batch.

Whereas the eval_loss is computed on the entire training dataset.

When I print it out, should I be recalculating the train_loss against the entire training split instead of the last batch?

for epoch in range(epochs):
    # Loop over batches.
    for i, batch in enumerate(samples_train['features']):
        
        train_preds = model(samples_train['features'][i])
        train_loss = loss_fn(train_preds, samples_train['labels'][i])

        optimizer.zero_grad()
        train_loss.backward()
        optimizer.step()
        
    # Only the training data is batched.
    eval_preds = model(samples_evaluate['features'])
    eval_loss = loss_fn(eval_preds, samples_evaluate['labels'])
    
    print(f"Epoch: {epoch}, Train_Loss: {float(train_loss)},  Eval_Loss: {float(eval_loss)}")

Answer 1

The losses should be calculated over the whole epoch (i.e. the whole dataset) instead of just the single batch. To implement this you could have a running count which adds up the losses of the individual batches and divides it by the number of batches after the epoch ends.