roboflow/supervision · error · ValueError

Predictions must have shape (M, {expected_pred_cols}). Got {

Error message

Predictions must have shape (M, {expected_pred_cols}). Got {predictions.shape} instead.

What it means

Error "Predictions must have shape (M, {expected_pred_cols}). Got {predictions.shape} instead." thrown in roboflow/supervision.

Source

Thrown at src/supervision/metrics/detection.py:909

                Detections with lower iou will be classified as `FP`.
            metric_target: The type of detection data to use.
                Determines IoU function (`box_iou_batch` vs
                `oriented_box_iou_batch`) and coordinate column count.
                `MetricTarget.MASKS` is not supported.

        Returns:
            Confusion matrix based on a single image.
        """
        _assert_supported_target(metric_target)

        expected_pred_cols = (
            10 if metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES else 6
        )
        expected_target_cols = (
            9 if metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES else 5
        )
        if predictions.ndim != 2 or predictions.shape[1] != expected_pred_cols:
            raise ValueError(
                f"Predictions must have shape (M, {expected_pred_cols}). "
                f"Got {predictions.shape} instead."
            )
        if targets.ndim != 2 or targets.shape[1] != expected_target_cols:
            raise ValueError(
                f"Targets must have shape (N, {expected_target_cols}). "
                f"Got {targets.shape} instead."
            )

        result_matrix: npt.NDArray[np.int32] = np.zeros(
            (num_classes + 1, num_classes + 1), dtype=np.int32
        )

        # Filter predictions by confidence threshold
        coords_dim = 8 if metric_target == MetricTarget.ORIENTED_BOUNDING_BOXES else 4
        class_id_idx = coords_dim
        conf_idx = coords_dim + 1

View on GitHub (pinned to 7f254d9784)

Solutions

1. Reshape the predictions array to (M, expected_pred_cols) before calling.
2. Check for accidental transposition or extra dimensions in the predictions array.

When it happens

Trigger: Thrown at src/supervision/metrics/detection.py:909 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of roboflow/supervision@7f254d9784 (2026-08-15). Data as JSON: /api/errors/529f1037c78b7bbb. Report an issue: GitHub.