Learner.validate - what is it for?

Part 1 (2020)
1

Hi,

  1. what this function exactly do?
  2. how should I understand it just from documentation? (see bellow)
  • Learner.validate(ds_idx=1, dl=None, cbs=None)
  • Validate on dl with potential new cbs.
2

I think, from the source (https://github.com/fastai/fastai/blob/fbb89cffc832cd4922dc70d0cc788ee442d1f2eb/fastai/learner.py#L223), relevant part is

self._do_epoch_validate(ds_idx, dl)
where ds_idx = 1 (0=Training set, 1 = ValidationSet, 2 = Test Set)

Return the model output using just the validation set