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zamba.pytorch_lightning.video_modules

ZambaVideoClassificationLightningModule

Bases: ZambaClassificationLightningModule

Source code in zamba/pytorch_lightning/video_modules.py
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class ZambaVideoClassificationLightningModule(ZambaClassificationLightningModule):
    def on_train_start(self):
        metrics = {"val_macro_f1": {}}

        if self.num_classes > 2:
            metrics.update(
                {f"val_top_{k}_accuracy": {} for k in DEFAULT_TOP_K if k < self.num_classes}
            )
        else:
            metrics.update({"val_accuracy": {}})

        # write hparams to hparams.yaml file, log metrics to tb hparams tab
        self.logger.log_hyperparams(self.hparams, metrics)

    def training_step(self, batch, batch_idx):
        x, y = batch
        y_hat = self(x)
        loss = F.binary_cross_entropy_with_logits(y_hat, y)
        self.log("train_loss", loss.detach())
        self.training_step_outputs.append(loss)
        return loss

    def _val_step(self, batch, batch_idx):
        x, y = batch
        y_hat = self(x)
        loss = F.binary_cross_entropy_with_logits(y_hat, y)
        self.log("val_loss", loss.detach())

        y_proba = torch.sigmoid(y_hat.cpu()).numpy()
        return {
            "y_true": y.cpu().numpy().astype(int),
            "y_pred": y_proba.round().astype(int),
            "y_proba": y_proba,
        }

    def validation_step(self, batch, batch_idx):
        output = self._val_step(batch, batch_idx)
        self.validation_step_outputs.append(output)
        return output

    def test_step(self, batch, batch_idx):
        output = self._val_step(batch, batch_idx)
        self.test_step_outputs.append(output)
        return output

    @staticmethod
    def aggregate_step_outputs(
        outputs: Dict[str, np.ndarray],
    ) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
        y_true = np.vstack([output["y_true"] for output in outputs])
        y_pred = np.vstack([output["y_pred"] for output in outputs])
        y_proba = np.vstack([output["y_proba"] for output in outputs])

        return y_true, y_pred, y_proba

    def compute_and_log_metrics(
        self, y_true: np.ndarray, y_pred: np.ndarray, y_proba: np.ndarray, subset: str
    ):
        self.log(
            f"{subset}_macro_f1",
            f1_score(y_true, y_pred, average="macro", zero_division=0),
        )

        # if only two classes, skip top_k accuracy since not enough classes
        if self.num_classes > 2:
            for k in DEFAULT_TOP_K:
                if k < self.num_classes:
                    self.log(
                        f"{subset}_top_{k}_accuracy",
                        top_k_accuracy_score(
                            y_true.argmax(
                                axis=1
                            ),  # top k accuracy only supports single label case
                            y_proba,
                            labels=np.arange(y_proba.shape[1]),
                            k=k,
                        ),
                    )
        else:
            self.log(f"{subset}_accuracy", accuracy_score(y_true, y_pred))

        for metric_name, label, metric in compute_species_specific_metrics(
            y_true, y_pred, self.species
        ):
            self.log(f"species/{subset}_{metric_name}/{label}", metric)

    def on_validation_epoch_end(self):
        """Aggregates validation_step outputs to compute and log the validation macro F1 and top K
        metrics.

        Args:
            outputs (List[dict]): list of output dictionaries from each validation step
                containing y_pred and y_true.
        """
        y_true, y_pred, y_proba = self.aggregate_step_outputs(self.validation_step_outputs)
        self.compute_and_log_metrics(y_true, y_pred, y_proba, subset="val")
        self.validation_step_outputs.clear()  # free memory

    def on_test_epoch_end(self):
        y_true, y_pred, y_proba = self.aggregate_step_outputs(self.test_step_outputs)
        self.compute_and_log_metrics(y_true, y_pred, y_proba, subset="test")
        self.test_step_outputs.clear()  # free memory

    def predict_step(self, batch, batch_idx, dataloader_idx: Optional[int] = None):
        x, y = batch
        y_hat = self(x)
        pred = torch.sigmoid(y_hat).cpu().numpy()
        return pred

on_validation_epoch_end()

Aggregates validation_step outputs to compute and log the validation macro F1 and top K metrics.

Parameters:

Name Type Description Default
outputs List[dict]

list of output dictionaries from each validation step containing y_pred and y_true.

required
Source code in zamba/pytorch_lightning/video_modules.py
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def on_validation_epoch_end(self):
    """Aggregates validation_step outputs to compute and log the validation macro F1 and top K
    metrics.

    Args:
        outputs (List[dict]): list of output dictionaries from each validation step
            containing y_pred and y_true.
    """
    y_true, y_pred, y_proba = self.aggregate_step_outputs(self.validation_step_outputs)
    self.compute_and_log_metrics(y_true, y_pred, y_proba, subset="val")
    self.validation_step_outputs.clear()  # free memory