roboflow/supervision · error · ValueError

Confusion matrix must have shape (..., 3), got {confusion_ma

Error message

Confusion matrix must have shape (..., 3), got {confusion_matrix.shape}

What it means

Error "Confusion matrix must have shape (..., 3), got {confusion_matrix.shape}" thrown in roboflow/supervision.

Source

Thrown at src/supervision/metrics/recall.py:520

        result: npt.NDArray[np.float64] = confusion_matrix
        return result

    @staticmethod
    def _compute_recall(
        confusion_matrix: npt.NDArray[np.float64],
    ) -> npt.NDArray[np.float64]:
        """
        Broadcastable function, computing the recall from the confusion matrix.

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

        Returns:
            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.divide(
            true_positives,
            denominator,
            out=np.zeros_like(true_positives),
            where=denominator != 0,
        )

        result_recall: npt.NDArray[np.float64] = recall
        return result_recall

    def _detections_content(

View on GitHub (pinned to 7f254d9784)

Solutions

1. Provide a confusion matrix whose last dimension is 3 (true positives, false positives, false negatives per cell).
2. Do not construct the matrix manually; use the metric's own computation methods to build it.

When it happens

Trigger: Thrown at src/supervision/metrics/recall.py:520 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/e1e42eb32fb90cfb. Report an issue: GitHub.