Builtin colormaps, colormap handling utilities, and the ScalarMappable mixin.

See also

Colormap reference for a list of builtin colormaps.

Creating Colormaps in Matplotlib for examples of how to make colormaps.

Choosing Colormaps in Matplotlib an in-depth discussion of choosing colormaps.

Colormap Normalization for more details about data normalization.

class, cmap=None)[source]

Bases: object

This is a mixin class to support scalar data to RGBA mapping. The ScalarMappable makes use of data normalization before returning RGBA colors from the given colormap.

normmatplotlib.colors.Normalize instance

The normalizing object which scales data, typically into the interval [0, 1]. If None, norm defaults to a colors.Normalize object which initializes its scaling based on the first data processed.

cmapstr or Colormap instance

The colormap used to map normalized data values to RGBA colors.

add_checker(self, checker)[source]

Add an entry to a dictionary of boolean flags that are set to True when the mappable is changed.


Autoscale the scalar limits on the norm instance using the current array


Autoscale the scalar limits on the norm instance using the current array, changing only limits that are None


Call this whenever the mappable is changed to notify all the callbackSM listeners to the 'changed' signal

check_update(self, checker)[source]

If mappable has changed since the last check, return True; else return False


The Colormap instance of this ScalarMappable.


The last colorbar associated with this ScalarMappable. May be None.


Always returns 1.


Return the array


return the min, max of the color limits for image scaling


return the colormap


The Normalization instance of this ScalarMappable.

set_array(self, A)[source]

Set the image array from numpy array A.

set_clim(self, vmin=None, vmax=None)[source]

Set the norm limits for image scaling.

vmin, vmaxfloat

The limits.

The limits may also be passed as a tuple (vmin, vmax) as a single positional argument.

set_cmap(self, cmap)[source]

set the colormap for luminance data

cmapcolormap or registered colormap name
set_norm(self, norm)[source]

Set the normalization instance.



If there are any colorbars using the mappable for this norm, setting the norm of the mappable will reset the norm, locator, and formatters on the colorbar to default.

to_rgba(self, x, alpha=None, bytes=False, norm=True)[source]

Return a normalized rgba array corresponding to x.

In the normal case, x is a 1-D or 2-D sequence of scalars, and the corresponding ndarray of rgba values will be returned, based on the norm and colormap set for this ScalarMappable.

There is one special case, for handling images that are already rgb or rgba, such as might have been read from an image file. If x is an ndarray with 3 dimensions, and the last dimension is either 3 or 4, then it will be treated as an rgb or rgba array, and no mapping will be done. The array can be uint8, or it can be floating point with values in the 0-1 range; otherwise a ValueError will be raised. If it is a masked array, the mask will be ignored. If the last dimension is 3, the alpha kwarg (defaulting to 1) will be used to fill in the transparency. If the last dimension is 4, the alpha kwarg is ignored; it does not replace the pre-existing alpha. A ValueError will be raised if the third dimension is other than 3 or 4.

In either case, if bytes is False (default), the rgba array will be floats in the 0-1 range; if it is True, the returned rgba array will be uint8 in the 0 to 255 range.

If norm is False, no normalization of the input data is performed, and it is assumed to be in the range (0-1)., lut=None)[source]

Get a colormap instance, defaulting to rc values if name is None.

Colormaps added with register_cmap() take precedence over built-in colormaps.

namematplotlib.colors.Colormap or str or None, default: None

If a Colormap instance, it will be returned. Otherwise, the name of a colormap known to Matplotlib, which will be resampled by lut. The default, None, means rcParams["image.cmap"] (default: 'viridis').

lutint or None, default: None

If name is not already a Colormap instance and lut is not None, the colormap will be resampled to have lut entries in the lookup table., cmap=None, data=None, lut=None)[source]

Add a colormap to the set recognized by get_cmap().

It can be used in two ways:

register_cmap(name='swirly', cmap=swirly_cmap)

register_cmap(name='choppy', data=choppydata, lut=128)

In the first case, cmap must be a matplotlib.colors.Colormap instance. The name is optional; if absent, the name will be the name attribute of the cmap.

In the second case, the three arguments are passed to the LinearSegmentedColormap initializer, and the resulting colormap is registered.[source]

[Deprecated] Can only handle specification data in dictionary format.


Deprecated since version 3.2.