Class MultivarColormap

lib/matplotlib/colors.py:1424–1676

Class for holding multiple `~matplotlib.colors.Colormap` for use in a `~matplotlib.cm.ScalarMappable` object

class MultivarColormap:
    """
    Class for holding multiple `~matplotlib.colors.Colormap` for use in a
    `~matplotlib.cm.ScalarMappable` object
    """
    def __init__(self, colormaps, combination_mode, name='multivariate colormap'):
        """
        Parameters
        ----------
        colormaps: list or tuple of `~matplotlib.colors.Colormap` objects
            The individual colormaps that are combined
        combination_mode: str, 'sRGB_add' or 'sRGB_sub'
            Describe how colormaps are combined in sRGB space

            - If 'sRGB_add' -> Mixing produces brighter colors
              `sRGB = sum(colors)`
            - If 'sRGB_sub' -> Mixing produces darker colors
              `sRGB = 1 - sum(1 - colors)`
        name : str, optional
            The name of the colormap family.
        """
        self.name = name

        if not np.iterable(colormaps) \
           or len(colormaps) == 1 \
           or isinstance(colormaps, str):
            raise ValueError("A MultivarColormap must have more than one colormap.")
        colormaps = list(colormaps)  # ensure cmaps is a list, i.e. not a tuple
        for i, cmap in enumerate(colormaps):
            if isinstance(cmap, str):
                colormaps[i] = mpl.colormaps[cmap]
            elif not isinstance(cmap, Colormap):
                raise ValueError("colormaps must be a list of objects that subclass"
                                 " Colormap or a name found in the colormap registry.")

        self._colormaps = colormaps
        _api.check_in_list(['sRGB_add', 'sRGB_sub'], combination_mode=combination_mode)
        self._combination_mode = combination_mode
        self.n_variates = len(colormaps)
        self._rgba_bad = (0.0, 0.0, 0.0, 0.0)  # If bad, don't paint anything.

    def __call__(self, X, alpha=None, bytes=False, clip=True):
        r"""
        Parameters
        ----------
        X : tuple (X0, X1, ...) of length equal to the number of colormaps
            X0, X1 ...:
            float or int, `~numpy.ndarray` or scalar
            The data value(s) to convert to RGBA.
            For floats, *Xi...* should be in the interval ``[0.0, 1.0]`` to
            return the RGBA values ``X*100`` percent along the Colormap line.
            For integers, *Xi...*  should be in the interval ``[0, self[i].N)`` to
            return RGBA values *indexed* from colormap [i] with index ``Xi``, where
            self[i] is colormap i.
        alpha : float or array-like or None
            Alpha must be a scalar between 0 and 1, a sequence of such
            floats with shape matching *Xi*, or None.
        bytes : bool, default: False