Today I learned

Fastai:

  1. Validation vs test data:

    1. Validation set: used actively during training to calculate and minimize loss.
    2. Test set: (at least in Fastai) it is used unlabeled, the assumption being that we need to predict on test data using our trained model.
  2. Force GC (i.e. garbage collection) in Python:

    learn = None
    
    import gc
    gc.collect()