Mean Average Recall¶

MeanAverageRecall

Bases: Metric

Mean Average Recall (mAR) measures how well the model detects and retrieves relevant objects by averaging recall over multiple IoU thresholds, classes and detection limits.

Intuitively, while Recall measures the ability to find all relevant objects, mAR narrows down how many detections are considered for each class. For example, mAR @ 100 considers the top 100 highest confidence detections for each class. mAR @ 1 considers only the highest confidence detection for each class.

Example

import supervision as sv
from supervision.metrics import MeanAverageRecall

predictions = sv.Detections(...)
targets = sv.Detections(...)

map_metric = MeanAverageRecall()
map_result = map_metric.update(predictions, targets).compute()

print(mar_results.mar_at_100)
# 0.5241

print(mar_results)
# MeanAverageRecallResult:
# Metric target:    MetricTarget.BOXES
# mAR @ 1:    0.1362
# mAR @ 10:   0.4239
# mAR @ 100:  0.5241
# max detections: [1  10 100]
# IoU thresh:     [0.5  0.55  0.6  ...]
# mAR per class:
# 0: [0.78571  0.78571  0.78571  ...]
# ...
# Small objects: ...
# Medium objects: ...
# Large objects: ...

mar_results.plot()

example_plot

Source code in supervision/metrics/mean_average_recall.py

class MeanAverageRecall(Metric):
    """
    Mean Average Recall (mAR) measures how well the model detects
    and retrieves relevant objects by averaging recall over multiple
    IoU thresholds, classes and detection limits.

    Intuitively, while Recall measures the ability to find all relevant
    objects, mAR narrows down how many detections are considered for each
    class. For example, mAR @ 100 considers the top 100 highest confidence
    detections for each class. mAR @ 1 considers only the highest
    confidence detection for each class.

    Example:
        ```python
        import supervision as sv
        from supervision.metrics import MeanAverageRecall

        predictions = sv.Detections(...)
        targets = sv.Detections(...)

        map_metric = MeanAverageRecall()
        map_result = map_metric.update(predictions, targets).compute()

        print(mar_results.mar_at_100)
        # 0.5241

        print(mar_results)
        # MeanAverageRecallResult:
        # Metric target:    MetricTarget.BOXES
        # mAR @ 1:    0.1362
        # mAR @ 10:   0.4239
        # mAR @ 100:  0.5241
        # max detections: [1  10 100]
        # IoU thresh:     [0.5  0.55  0.6  ...]
        # mAR per class:
        # 0: [0.78571  0.78571  0.78571  ...]
        # ...
        # Small objects: ...
        # Medium objects: ...
        # Large objects: ...

        mar_results.plot()
        ```

    ![example_plot](\
        https://media.roboflow.com/supervision-docs/metrics/mAR_plot_example.png\
        ){ align=center width="800" }
    """

    def __init__(
        self,
        metric_target: MetricTarget = MetricTarget.BOXES,
    ):
        """
        Initialize the Mean Average Recall metric.

        Args:
            metric_target (MetricTarget): The type of detection data to use.
        """
        self._metric_target = metric_target

        self._predictions_list: List[Detections] = []
        self._targets_list: List[Detections] = []

        self.max_detections = np.array([1, 10, 100])

    def reset(self) -> None:
        """
        Reset the metric to its initial state, clearing all stored data.
        """
        self._predictions_list = []
        self._targets_list = []

    def update(
        self,
        predictions: Union[Detections, List[Detections]],
        targets: Union[Detections, List[Detections]],
    ) -> MeanAverageRecall:
        """
        Add new predictions and targets to the metric, but do not compute the result.

        Args:
            predictions (Union[Detections, List[Detections]]): The predicted detections.
            targets (Union[Detections, List[Detections]]): The target detections.

        Returns:
            (Recall): The updated metric instance.
        """
        if not isinstance(predictions, list):
            predictions = [predictions]
        if not isinstance(targets, list):
            targets = [targets]

        if len(predictions) != len(targets):
            raise ValueError(
                f"The number of predictions ({len(predictions)}) and"
                f" targets ({len(targets)}) during the update must be the same."
            )

        self._predictions_list.extend(predictions)
        self._targets_list.extend(targets)

        return self

    def compute(self) -> MeanAverageRecallResult:
        """
        Calculate the Mean Average Recall metric based on the stored predictions
        and ground-truth, at different IoU thresholds and maximum detection counts.

        Returns:
            (MeanAverageRecallResult): The Mean Average Recall metric result.
        """
        result = self._compute(self._predictions_list, self._targets_list)

        small_predictions, small_targets = self._filter_predictions_and_targets_by_size(
            self._predictions_list, self._targets_list, ObjectSizeCategory.SMALL
        )
        result.small_objects = self._compute(small_predictions, small_targets)

        medium_predictions, medium_targets = (
            self._filter_predictions_and_targets_by_size(
                self._predictions_list, self._targets_list, ObjectSizeCategory.MEDIUM
            )
        )
        result.medium_objects = self._compute(medium_predictions, medium_targets)

        large_predictions, large_targets = self._filter_predictions_and_targets_by_size(
            self._predictions_list, self._targets_list, ObjectSizeCategory.LARGE
        )
        result.large_objects = self._compute(large_predictions, large_targets)

        return result

    def _compute(
        self, predictions_list: List[Detections], targets_list: List[Detections]
    ) -> MeanAverageRecallResult:
        iou_thresholds = np.linspace(0.5, 0.95, 10)
        stats = []

        for predictions, targets in zip(predictions_list, targets_list):
            prediction_contents = self._detections_content(predictions)
            target_contents = self._detections_content(targets)

            if len(targets) > 0:
                if len(predictions) == 0:
                    stats.append(
                        (
                            np.zeros((0, iou_thresholds.size), dtype=bool),
                            np.zeros((0,), dtype=np.float32),
                            np.zeros((0,), dtype=int),
                            targets.class_id,
                        )
                    )

                else:
                    if self._metric_target == MetricTarget.BOXES:
                        iou = box_iou_batch(target_contents, prediction_contents)
                    elif self._metric_target == MetricTarget.MASKS:
                        iou = mask_iou_batch(target_contents, prediction_contents)
                    elif self._metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES:
                        iou = oriented_box_iou_batch(
                            target_contents, prediction_contents
                        )
                    else:
                        raise ValueError(
                            "Unsupported metric target for IoU calculation"
                        )

                    matches = self._match_detection_batch(
                        predictions.class_id, targets.class_id, iou, iou_thresholds
                    )
                    stats.append(
                        (
                            matches,
                            predictions.confidence,
                            predictions.class_id,
                            targets.class_id,
                        )
                    )

        if not stats:
            return MeanAverageRecallResult(
                metric_target=self._metric_target,
                recall_scores=np.zeros(iou_thresholds.shape[0]),
                recall_per_class=np.zeros((0, iou_thresholds.shape[0])),
                max_detections=self.max_detections,
                iou_thresholds=iou_thresholds,
                matched_classes=np.array([], dtype=int),
                small_objects=None,
                medium_objects=None,
                large_objects=None,
            )

        concatenated_stats = [np.concatenate(items, 0) for items in zip(*stats)]
        recall_scores_per_k, recall_per_class, unique_classes = (
            self._compute_average_recall_for_classes(*concatenated_stats)
        )

        return MeanAverageRecallResult(
            metric_target=self._metric_target,
            recall_scores=recall_scores_per_k,
            recall_per_class=recall_per_class,
            max_detections=self.max_detections,
            iou_thresholds=iou_thresholds,
            matched_classes=unique_classes,
            small_objects=None,
            medium_objects=None,
            large_objects=None,
        )

    def _compute_average_recall_for_classes(
        self,
        matches: np.ndarray,
        prediction_confidence: np.ndarray,
        prediction_class_ids: np.ndarray,
        true_class_ids: np.ndarray,
    ) -> Tuple[np.ndarray, np.ndarray, np.ndarray]:
        sorted_indices = np.argsort(-prediction_confidence)
        matches = matches[sorted_indices]
        prediction_class_ids = prediction_class_ids[sorted_indices]
        unique_classes, class_counts = np.unique(true_class_ids, return_counts=True)

        recalls_at_k = []
        for max_detections in self.max_detections:
            # Shape: PxTh,P,C,C -> CxThx3
            confusion_matrix = self._compute_confusion_matrix(
                matches,
                prediction_class_ids,
                unique_classes,
                class_counts,
                max_detections=max_detections,
            )

            # Shape: CxThx3 -> CxTh
            recall_per_class = self._compute_recall(confusion_matrix)
            recalls_at_k.append(recall_per_class)

        # Shape: KxCxTh -> KxC
        recalls_at_k = np.array(recalls_at_k)
        average_recall_per_class = np.mean(recalls_at_k, axis=2)

        # Shape: KxC -> K
        recall_scores = np.mean(average_recall_per_class, axis=1)

        return recall_scores, recall_per_class, unique_classes

    @staticmethod
    def _match_detection_batch(
        predictions_classes: np.ndarray,
        target_classes: np.ndarray,
        iou: np.ndarray,
        iou_thresholds: np.ndarray,
    ) -> np.ndarray:
        num_predictions, num_iou_levels = (
            predictions_classes.shape[0],
            iou_thresholds.shape[0],
        )
        correct = np.zeros((num_predictions, num_iou_levels), dtype=bool)
        correct_class = target_classes[:, None] == predictions_classes

        for i, iou_level in enumerate(iou_thresholds):
            matched_indices = np.where((iou >= iou_level) & correct_class)

            if matched_indices[0].shape[0]:
                combined_indices = np.stack(matched_indices, axis=1)
                iou_values = iou[matched_indices][:, None]
                matches = np.hstack([combined_indices, iou_values])

                if matched_indices[0].shape[0] > 1:
                    matches = matches[matches[:, 2].argsort()[::-1]]
                    matches = matches[np.unique(matches[:, 1], return_index=True)[1]]
                    matches = matches[np.unique(matches[:, 0], return_index=True)[1]]

                correct[matches[:, 1].astype(int), i] = True

        return correct

    @staticmethod
    def _compute_confusion_matrix(
        sorted_matches: np.ndarray,
        sorted_prediction_class_ids: np.ndarray,
        unique_classes: np.ndarray,
        class_counts: np.ndarray,
        max_detections: Optional[int] = None,
    ) -> np.ndarray:
        """
        Compute the confusion matrix for each class and IoU threshold.

        Assumes the matches and prediction_class_ids are sorted by confidence
        in descending order.

        Args:
            sorted_matches: np.ndarray, bool, shape (P, Th), that is True
                if the prediction is a true positive at the given IoU threshold.
            sorted_prediction_class_ids: np.ndarray, int, shape (P,), containing
                the class id for each prediction.
            unique_classes: np.ndarray, int, shape (C,), containing the unique
                class ids.
            class_counts: np.ndarray, int, shape (C,), containing the number
                of true instances for each class.
            max_detections: Optional[int], the maximum number of detections to
                consider for each class. Extra detections are considered false
                positives. By default, all detections are considered.

        Returns:
            np.ndarray, shape (C, Th, 3), containing the true positives, false
                positives, and false negatives for each class and IoU threshold.
        """
        num_thresholds = sorted_matches.shape[1]
        num_classes = unique_classes.shape[0]

        confusion_matrix = np.zeros((num_classes, num_thresholds, 3))
        for class_idx, class_id in enumerate(unique_classes):
            is_class = sorted_prediction_class_ids == class_id
            num_true = class_counts[class_idx]
            num_predictions = is_class.sum()

            if num_predictions == 0:
                true_positives = np.zeros(num_thresholds)
                false_positives = np.zeros(num_thresholds)
                false_negatives = np.full(num_thresholds, num_true)
            elif num_true == 0:
                true_positives = np.zeros(num_thresholds)
                false_positives = np.full(num_thresholds, num_predictions)
                false_negatives = np.zeros(num_thresholds)
            else:
                limited_matches = sorted_matches[is_class][slice(max_detections)]
                true_positives = limited_matches.sum(0)

                false_positives = (1 - limited_matches).sum(0)
                false_negatives = num_true - true_positives
                false_negatives = num_true - true_positives
            confusion_matrix[class_idx] = np.stack(
                [true_positives, false_positives, false_negatives], axis=1
            )

        return confusion_matrix

    @staticmethod
    def _compute_recall(confusion_matrix: np.ndarray) -> np.ndarray:
        """
        Broadcastable function, computing the recall from the confusion matrix.

        Arguments:
            confusion_matrix: np.ndarray, shape (N, ..., 3), where the last dimension
                contains the true positives, false positives, and false negatives.

        Returns:
            np.ndarray, shape (N, ...), containing the recall for each element.
        """
        if not confusion_matrix.shape[-1] == 3:
            raise ValueError(
                f"Confusion matrix must have shape (..., 3), got "
                f"{confusion_matrix.shape}"
            )
        true_positives = confusion_matrix[..., 0]
        false_negatives = confusion_matrix[..., 2]

        denominator = true_positives + false_negatives
        recall = np.where(denominator == 0, 0, true_positives / denominator)

        return recall

    def _detections_content(self, detections: Detections) -> np.ndarray:
        """Return boxes, masks or oriented bounding boxes from detections."""
        if self._metric_target == MetricTarget.BOXES:
            return detections.xyxy
        if self._metric_target == MetricTarget.MASKS:
            return (
                detections.mask
                if detections.mask is not None
                else self._make_empty_content()
            )
        if self._metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES:
            obb = detections.data.get(ORIENTED_BOX_COORDINATES)
            if obb is not None and len(obb) > 0:
                return np.array(obb, dtype=np.float32)
            return self._make_empty_content()
        raise ValueError(f"Invalid metric target: {self._metric_target}")

    def _make_empty_content(self) -> np.ndarray:
        if self._metric_target == MetricTarget.BOXES:
            return np.empty((0, 4), dtype=np.float32)
        if self._metric_target == MetricTarget.MASKS:
            return np.empty((0, 0, 0), dtype=bool)
        if self._metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES:
            return np.empty((0, 4, 2), dtype=np.float32)
        raise ValueError(f"Invalid metric target: {self._metric_target}")

    def _filter_detections_by_size(
        self, detections: Detections, size_category: ObjectSizeCategory
    ) -> Detections:
        """Return a copy of detections with contents filtered by object size."""
        new_detections = deepcopy(detections)
        if detections.is_empty() or size_category == ObjectSizeCategory.ANY:
            return new_detections

        sizes = get_detection_size_category(new_detections, self._metric_target)
        size_mask = sizes == size_category.value

        new_detections.xyxy = new_detections.xyxy[size_mask]
        if new_detections.mask is not None:
            new_detections.mask = new_detections.mask[size_mask]
        if new_detections.class_id is not None:
            new_detections.class_id = new_detections.class_id[size_mask]
        if new_detections.confidence is not None:
            new_detections.confidence = new_detections.confidence[size_mask]
        if new_detections.tracker_id is not None:
            new_detections.tracker_id = new_detections.tracker_id[size_mask]
        if new_detections.data is not None:
            for key, value in new_detections.data.items():
                new_detections.data[key] = np.array(value)[size_mask]

        return new_detections

    def _filter_predictions_and_targets_by_size(
        self,
        predictions_list: List[Detections],
        targets_list: List[Detections],
        size_category: ObjectSizeCategory,
    ) -> Tuple[List[Detections], List[Detections]]:
        new_predictions_list = []
        new_targets_list = []
        for predictions, targets in zip(predictions_list, targets_list):
            new_predictions_list.append(
                self._filter_detections_by_size(predictions, size_category)
            )
            new_targets_list.append(
                self._filter_detections_by_size(targets, size_category)
            )
        return new_predictions_list, new_targets_list

Functions¶

`init(metric_target=MetricTarget.BOXES)` ¶

Initialize the Mean Average Recall metric.

Parameters:

Name	Type	Description	Default
`metric_target`	`MetricTarget`	The type of detection data to use.	`BOXES`

Source code in supervision/metrics/mean_average_recall.py

def __init__(
    self,
    metric_target: MetricTarget = MetricTarget.BOXES,
):
    """
    Initialize the Mean Average Recall metric.

    Args:
        metric_target (MetricTarget): The type of detection data to use.
    """
    self._metric_target = metric_target

    self._predictions_list: List[Detections] = []
    self._targets_list: List[Detections] = []

    self.max_detections = np.array([1, 10, 100])

`compute()` ¶

Calculate the Mean Average Recall metric based on the stored predictions and ground-truth, at different IoU thresholds and maximum detection counts.

Returns:

Type	Description
`MeanAverageRecallResult`	The Mean Average Recall metric result.

Source code in supervision/metrics/mean_average_recall.py

def compute(self) -> MeanAverageRecallResult:
    """
    Calculate the Mean Average Recall metric based on the stored predictions
    and ground-truth, at different IoU thresholds and maximum detection counts.

    Returns:
        (MeanAverageRecallResult): The Mean Average Recall metric result.
    """
    result = self._compute(self._predictions_list, self._targets_list)

    small_predictions, small_targets = self._filter_predictions_and_targets_by_size(
        self._predictions_list, self._targets_list, ObjectSizeCategory.SMALL
    )
    result.small_objects = self._compute(small_predictions, small_targets)

    medium_predictions, medium_targets = (
        self._filter_predictions_and_targets_by_size(
            self._predictions_list, self._targets_list, ObjectSizeCategory.MEDIUM
        )
    )
    result.medium_objects = self._compute(medium_predictions, medium_targets)

    large_predictions, large_targets = self._filter_predictions_and_targets_by_size(
        self._predictions_list, self._targets_list, ObjectSizeCategory.LARGE
    )
    result.large_objects = self._compute(large_predictions, large_targets)

    return result

`reset()` ¶

Reset the metric to its initial state, clearing all stored data.

Source code in supervision/metrics/mean_average_recall.py

def reset(self) -> None:
    """
    Reset the metric to its initial state, clearing all stored data.
    """
    self._predictions_list = []
    self._targets_list = []

`update(predictions, targets)` ¶

Add new predictions and targets to the metric, but do not compute the result.

Parameters:

Name	Type	Description	Default
`predictions`	`Union[Detections, List[Detections]]`	The predicted detections.	required
`targets`	`Union[Detections, List[Detections]]`	The target detections.	required

Returns:

Type	Description
`Recall`	The updated metric instance.

Source code in supervision/metrics/mean_average_recall.py

def update(
    self,
    predictions: Union[Detections, List[Detections]],
    targets: Union[Detections, List[Detections]],
) -> MeanAverageRecall:
    """
    Add new predictions and targets to the metric, but do not compute the result.

    Args:
        predictions (Union[Detections, List[Detections]]): The predicted detections.
        targets (Union[Detections, List[Detections]]): The target detections.

    Returns:
        (Recall): The updated metric instance.
    """
    if not isinstance(predictions, list):
        predictions = [predictions]
    if not isinstance(targets, list):
        targets = [targets]

    if len(predictions) != len(targets):
        raise ValueError(
            f"The number of predictions ({len(predictions)}) and"
            f" targets ({len(targets)}) during the update must be the same."
        )

    self._predictions_list.extend(predictions)
    self._targets_list.extend(targets)

    return self