def loss_batch(
model: nn.Module,
xb: Tensor,
yb: Tensor,
loss_func: OptLossFunc = None,
opt: OptOptimizer = None,
cb_handler: Optional[CallbackHandler] = None
) -> Tuple[Union[Tensor, int, float, str]]:
"Calculate loss and metrics for a batch, call out to callbacks as necessary."
cb_handler = ifnone(cb_handler, CallbackHandler())
if not is_listy(xb): xb = [xb]
if not is_listy(yb): yb = [yb]
out = model(*xb)
out = cb_handler.on_loss_begin(out)
if not loss_func: return to_detach(out), yb[0].detach()
loss = loss_func(out, *yb)
if opt is not None:
loss, skip_bwd = cb_handler.on_backward_begin(loss)
if not skip_bwd: loss.backward()
if not cb_handler.on_backward_end(): opt.step()
if not cb_handler.on_step_end(): opt.zero_grad()
return loss.detach().cpu()
def on_batch_end(self, last_output, last_target, **kwargs):
"Update metric computation with `last_output` and `last_target`."
if not is_listy(last_target): last_target = [last_target]
met_val = self.func(last_output, *last_target)
if met_val is not None:
self.count += last_target[0].size(0)
self.val += last_target[0].size(0) * met_val.detach().cpu()
def validate_w_dropout(
model: nn.Module,
dl: DataLoader,
loss_func: OptLossFunc = None,
cb_handler: Optional[CallbackHandler] = None,
pbar: Optional[PBar] = None,
average=True,
n_batch: Optional[int] = None
) -> Iterator[Tuple[Union[Tensor, int], ...]]:
"Calculate `loss_func` of `model` on `dl` in evaluation mode."
model.train()
with torch.no_grad():
val_losses, nums = [], []
if cb_handler: cb_handler.set_dl(dl)
for xb, yb in progress_bar(dl, parent=pbar, leave=(pbar is not None)):
if cb_handler:
xb, yb = cb_handler.on_batch_begin(xb, yb, train=False)
val_loss = loss_batch(model,
xb,
yb,
loss_func,
cb_handler=cb_handler)
val_losses.append(val_loss)
if not is_listy(yb): yb = [yb]
nums.append(yb[0].shape[0])
if cb_handler and cb_handler.on_batch_end(val_losses[-1]): break
if n_batch and (len(nums) >= n_batch): break
nums = np.array(nums, dtype=np.float32)
if average:
return (to_np(torch.stack(val_losses)) * nums).sum() / nums.sum()
else:
return val_losses
model.eval()
def make_data_bunch_from_df(cls,
path: PathOrStr,
train_df: DataFrame,
valid_df: DataFrame,
tokenizer: Tokenizer = None,
vocab: Vocab = None,
classes: Collection[str] = None,
text_cols: IntsOrStrs = 1,
label_cols: IntsOrStrs = 0,
label_delim: str = None,
chunksize: int = 10000,
max_vocab: int = 60000,
label_cls: Callable = None,
min_freq: int = 2,
mark_fields: bool = False,
include_bos: bool = True,
include_eos: bool = False,
processor=None,
**kwargs) -> DataBunch:
"Create a `TextDataBunch` from DataFrames. `kwargs` are passed to the dataloader creation."
assert processor is None or tokenizer is None, "Processor and tokenizer are mutually exclusive."
if processor is None:
processor = fastai.text.data._get_processor(tokenizer=tokenizer,
vocab=vocab,
chunksize=chunksize,
max_vocab=max_vocab,
min_freq=min_freq,
mark_fields=mark_fields,
include_bos=include_bos,
include_eos=include_eos)
if classes is None and is_listy(label_cols) and len(label_cols) > 1:
classes = label_cols
src = ItemLists(
path,
TextList.from_df(train_df,
path,
cols=text_cols,
processor=processor,
label_cls=label_cls),
TextList.from_df(valid_df,
path,
cols=text_cols,
processor=processor,
label_cls=label_cls))
if cls == TextLMDataBunch:
src = src.label_for_lm()
else:
if label_delim is not None:
src = src.label_from_df(cols=label_cols,
classes=classes,
label_delim=label_delim)
else:
src = src.label_from_df(cols=label_cols, classes=classes)
return src.databunch(**kwargs)
def loss_batch(
model: nn.Module,
xb: Tensor,
yb: Tensor,
loss_func: OptLossFunc = None,
opt: OptOptimizer = None,
cb_handler: Optional[CallbackHandler] = None,
) -> Tuple[Union[Tensor, int, float, str]]:
"Calculate loss and metrics for a batch, call out to callbacks as necessary."
cb_handler = ifnone(cb_handler, CallbackHandler())
if not is_listy(xb):
xb = [xb]
if not is_listy(yb):
yb = [yb]
out = [model(x) for x in xb]
out = cb_handler.on_loss_begin(out)
if not loss_func:
return to_detach(out), yb[0].detach()
loss = loss_func(out)
if opt is not None:
loss = cb_handler.on_backward_begin(loss)
# fastai v1.0.52 introduced the possibility for the backwards step to
# be optional by returning a tuple here
# see https://github.com/fastai/fastai/commit/6fcaad870e0e833d325052b57e72e23a450ebc6f#diff-0730afdfa67f9712e46ad7866b0123f8L32
if type(loss) == tuple:
loss, skip_bwd = loss
if not skip_bwd:
loss.backward()
else:
loss.backward()
cb_handler.on_backward_end()
opt.step()
cb_handler.on_step_end()
opt.zero_grad()
return loss.detach().cpu()
def on_batch_end(self, last_output, last_target, **kwargs):
"Update metric computation with `last_output` and `last_target`."
if not is_listy(last_target): last_target = [last_target]
val = self.func(last_output, *last_target)
## If nan do not increase counter and return
if torch.isnan(val).tolist():
return
self.count += first_el(last_target).size(0)
if self.world:
val = val.clone()
dist.all_reduce(val, op=dist.ReduceOp.SUM)
val /= self.world
self.val += first_el(last_target).size(0) * val.detach().cpu()