matplotlib/matplotlib · error · ValueError

MultiNorm expects a sequence with one element per component

Error message

MultiNorm expects a sequence with one element per component as input, but got {data!r} instead

What it means

Error "MultiNorm expects a sequence with one element per component as input, but got {data!r} instead" thrown in matplotlib/matplotlib.

Source

Thrown at lib/matplotlib/colors.py:3622

        Returns
        -------
        tuple of np.ndarray

        """
        if isinstance(data, np.ndarray) and data.dtype.fields is not None:
            # structured array
            if len(data.dtype.fields) != n_components:
                raise ValueError(
                    "Structured array inputs to MultiNorm must have the same "
                    "number of fields as components in the MultiNorm. Expected "
                    f"{n_components}, but got {len(data.dtype.fields)} fields"
                    )
            else:
                return tuple(data[field] for field in data.dtype.names)
        try:
            n_elements = len(data)
        except TypeError:
            raise ValueError("MultiNorm expects a sequence with one element per "
                             f"component as input, but got {data!r} instead")
        if n_elements != n_components:
            if isinstance(data, np.ndarray) and data.shape[-1] == n_components:
                if len(data.shape) == 2:
                    raise ValueError(
                        f"MultiNorm expects a sequence with one element per component. "
                        "You can use `data_transposed = data.T` "
                        "to convert the input data of shape "
                        f"{data.shape} to a compatible shape {data.shape[::-1]}")
                else:
                    raise ValueError(
                        f"MultiNorm expects a sequence with one element per component. "
                        "You can use `data_as_list = [data[..., i] for i in "
                        "range(data.shape[-1])]` to convert the input data of shape "
                        f" {data.shape} to a compatible list")

            raise ValueError(
                "MultiNorm expects a sequence with one element per component. "

View on GitHub (pinned to b379c1b69e)

When it happens

Trigger: Thrown at lib/matplotlib/colors.py:3622 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of matplotlib/matplotlib@b379c1b69e (2026-08-21). Data as JSON: /api/errors/0a88addbb8a29639. Report an issue: GitHub.