matplotlib.colorbar

Colorbars are a visualization of the mapping from scalar values to colors. In Matplotlib they are drawn into a dedicated Axes.

classmatplotlib.colorbar.Colorbar(ax, mappable=None, *, cmap=None, norm=None, alpha=None, values=None, boundaries=None, orientation='vertical', ticklocation='auto', extend=None, spacing='uniform', ticks=None, format=None, drawedges=False, filled=True, extendfrac=None, extendrect=False, label='')[source]

Bases: object

Draw a colorbar in an existing axes.

Typically, colorbars are created using Figure.colorbar or pyplot.colorbar and associated with ScalarMappables (such as an AxesImage generated via imshow).

In order to draw a colorbar not associated with other elements in the figure, e.g. when showing a colormap by itself, one can create an empty ScalarMappable, or directly pass cmap and norm instead of mappable to Colorbar.

Useful public methods are set_label() and add_lines().

Parameters

axAxes

The Axes instance in which the colorbar is drawn.

mappableScalarMappable

The mappable whose colormap and norm will be used.

To show the under- and over- value colors, the mappable's norm should be specified as

norm = colors.Normalize(clip=False)

To show the colors versus index instead of on a 0-1 scale, use:

norm=colors.NoNorm()

cmapColormap, default: rcParams["image.cmap"] (default: 'viridis')

The colormap to use. This parameter is ignored, unless mappable is None.

normNormalize

The normalization to use. This parameter is ignored, unless mappable is None.

alphafloat

The colorbar transparency between 0 (transparent) and 1 (opaque).

values, boundaries

If unset, the colormap will be displayed on a 0-1 scale.

orientation{'vertical', 'horizontal'}

ticklocation{'auto', 'left', 'right', 'top', 'bottom'}

extend{'neither', 'both', 'min', 'max'}

spacing{'uniform', 'proportional'}

ticksLocator or array-like of float

formatstr or Formatter

drawedgesbool

filledbool

extendfrac

extendrec

labelstr

Attributes

axAxes

The Axes instance in which the colorbar is drawn.

lineslist

A list of LineCollection (empty if no lines were drawn).

dividersLineCollection

A LineCollection (empty if drawedges is False).

add_lines(*args, **kwargs)[source]

Draw lines on the colorbar.

The lines are appended to the list lines.

Parameters

levelsarray-like

The positions of the lines.

colorscolor or list of colors

Either a single color applying to all lines or one color value for each line.

linewidthsfloat or array-like

Either a single linewidth applying to all lines or one linewidth for each line.

erasebool, default: True

Whether to remove any previously added lines.

Notes

Alternatively, this method can also be called with the signature colorbar.add_lines(contour_set, erase=True), in which case levels, colors, and linewidths are taken from contour_set.

drag_pan(button, key, x, y)[source]

draw_all()[source]

Calculate any free parameters based on the current cmap and norm, and do all the drawing.

get_ticks(minor=False)[source]

Return the ticks as a list of locations.

Parameters

minorboolean, default: False

if True return the minor ticks.

minorticks_off()[source]

Turn the minor ticks of the colorbar off.

minorticks_on()[source]

Turn on colorbar minor ticks.

n_rasterize=50

propertypatch[source]

remove()[source]

Remove this colorbar from the figure.

If the colorbar was created with use_gridspec=True the previous gridspec is restored.

set_alpha(alpha)[source]

Set the transparency between 0 (transparent) and 1 (opaque).

If an array is provided, alpha will be set to None to use the transparency values associated with the colormap.

set_label(label, *, loc=None, **kwargs)[source]

Add a label to the long axis of the colorbar.

Parameters

labelstr

The label text.

locstr, optional

The location of the label.

• For horizontal orientation one of {'left', 'center', 'right'}
• For vertical orientation one of {'bottom', 'center', 'top'}

Defaults to rcParams["xaxis.labellocation"] (default: 'center') or rcParams["yaxis.labellocation"] (default: 'center') depending on the orientation.

**kwargs

Keyword arguments are passed to set_xlabel / set_ylabel. Supported keywords are labelpad and Text properties.

set_ticklabels(ticklabels, update_ticks=<deprecated parameter>, *, minor=False, **kwargs)[source]

Set tick labels.

Discouraged

The use of this method is discouraged, because of the dependency on tick positions. In most cases, you'll want to use set_ticks(positions, labels=labels) instead.

If you are using this method, you should always fix the tick positions before, e.g. by using Colorbar.set_ticks or by explicitly setting a FixedLocator on the long axis of the colorbar. Otherwise, ticks are free to move and the labels may end up in unexpected positions.

Parameters

ticklabelssequence of str or of Text

Texts for labeling each tick location in the sequence set by Colorbar.set_ticks; the number of labels must match the number of locations.

update_ticksbool, default: True

This keyword argument is ignored and will be be removed. Deprecated

minorbool

If True, set minor ticks instead of major ticks.

**kwargs

Text properties for the labels.

set_ticks(ticks, update_ticks=<deprecated parameter>, labels=None, *, minor=False, **kwargs)[source]

Set tick locations.

Parameters

tickslist of floats

List of tick locations.

labelslist of str, optional

List of tick labels. If not set, the labels show the data value.

minorbool, default: False

If False, set the major ticks; if True, the minor ticks.

**kwargs

Text properties for the labels. These take effect only if you pass labels. In other cases, please use tick_params.

update_normal(mappable)[source]

Update solid patches, lines, etc.

This is meant to be called when the norm of the image or contour plot to which this colorbar belongs changes.

If the norm on the mappable is different than before, this resets the locator and formatter for the axis, so if these have been customized, they will need to be customized again. However, if the norm only changes values of vmin, vmax or cmap then the old formatter and locator will be preserved.

update_ticks()[source]

Setup the ticks and ticklabels. This should not be needed by users.

matplotlib.colorbar.ColorbarBase[source]

alias of matplotlib.colorbar.Colorbar

classmatplotlib.colorbar.ColorbarPatch(ax, mappable=None, *, cmap=None, norm=None, alpha=None, values=None, boundaries=None, orientation='vertical', ticklocation='auto', extend=None, spacing='uniform', ticks=None, format=None, drawedges=False, filled=True, extendfrac=None, extendrect=False, label='')[source]

Bases: matplotlib.colorbar.Colorbar

[Deprecated]

Notes

Deprecated since version 3.4:

matplotlib.colorbar.colorbar_factory(cax, mappable, **kwargs)[source]

[Deprecated] Create a colorbar on the given axes for the given mappable.

Note

This is a low-level function to turn an existing axes into a colorbar axes. Typically, you'll want to use colorbar instead, which automatically handles creation and placement of a suitable axes as well.

Parameters

caxAxes

The Axes to turn into a colorbar.

mappableScalarMappable

The mappable to be described by the colorbar.

**kwargs

Keyword arguments are passed to the respective colorbar class.

Returns

Colorbar

The created colorbar instance.

Notes

Deprecated since version 3.4.

matplotlib.colorbar.make_axes(parents, location=None, orientation=None, fraction=0.15, shrink=1.0, aspect=20, **kw)[source]

Create an Axes suitable for a colorbar.

The axes is placed in the figure of the parents axes, by resizing and repositioning parents.

Parameters

parentsAxes or list of Axes

The Axes to use as parents for placing the colorbar.

locationNone or {'left', 'right', 'top', 'bottom'}

The location, relative to the parent axes, where the colorbar axes is created. It also determines the orientation of the colorbar (colorbars on the left and right are vertical, colorbars at the top and bottom are horizontal). If None, the location will come from the orientation if it is set (vertical colorbars on the right, horizontal ones at the bottom), or default to 'right' if orientation is unset.

orientationNone or {'vertical', 'horizontal'}

The orientation of the colorbar. It is preferable to set the location of the colorbar, as that also determines the orientation; passing incompatible values for location and orientation raises an exception.

fractionfloat, default: 0.15

Fraction of original axes to use for colorbar.

shrinkfloat, default: 1.0

Fraction by which to multiply the size of the colorbar.

aspectfloat, default: 20

Ratio of long to short dimensions.

Returns

caxAxes

The child axes.

kwdict

The reduced keyword dictionary to be passed when creating the colorbar instance.

Other Parameters

padfloat, default: 0.05 if vertical, 0.15 if horizontal

Fraction of original axes between colorbar and new image axes.

anchor(float, float), optional

The anchor point of the colorbar axes. Defaults to (0.0, 0.5) if vertical; (0.5, 1.0) if horizontal.

panchor(float, float), or False, optional

The anchor point of the colorbar parent axes. If False, the parent axes' anchor will be unchanged. Defaults to (1.0, 0.5) if vertical; (0.5, 0.0) if horizontal.

matplotlib.colorbar.make_axes_gridspec(parent, *, location=None, orientation=None, fraction=0.15, shrink=1.0, aspect=20, **kw)[source]

Create a SubplotBase suitable for a colorbar.

The axes is placed in the figure of the parent axes, by resizing and repositioning parent.

This function is similar to make_axes. Primary differences are

• make_axes_gridspec should only be used with a SubplotBase parent.
• make_axes creates an Axes; make_axes_gridspec creates a SubplotBase.
• make_axes updates the position of the parent. make_axes_gridspec replaces the grid_spec attribute of the parent with a new one.

While this function is meant to be compatible with make_axes, there could be some minor differences.

Parameters

parentAxes

The Axes to use as parent for placing the colorbar.

locationNone or {'left', 'right', 'top', 'bottom'}

The location, relative to the parent axes, where the colorbar axes is created. It also determines the orientation of the colorbar (colorbars on the left and right are vertical, colorbars at the top and bottom are horizontal). If None, the location will come from the orientation if it is set (vertical colorbars on the right, horizontal ones at the bottom), or default to 'right' if orientation is unset.

orientationNone or {'vertical', 'horizontal'}

The orientation of the colorbar. It is preferable to set the location of the colorbar, as that also determines the orientation; passing incompatible values for location and orientation raises an exception.

fractionfloat, default: 0.15

Fraction of original axes to use for colorbar.

shrinkfloat, default: 1.0

Fraction by which to multiply the size of the colorbar.

aspectfloat, default: 20

Ratio of long to short dimensions.

Returns

caxSubplotBase

The child axes.

kwdict

The reduced keyword dictionary to be passed when creating the colorbar instance.

Other Parameters

padfloat, default: 0.05 if vertical, 0.15 if horizontal

Fraction of original axes between colorbar and new image axes.

anchor(float, float), optional

The anchor point of the colorbar axes. Defaults to (0.0, 0.5) if vertical; (0.5, 1.0) if horizontal.

panchor(float, float), or False, optional

The anchor point of the colorbar parent axes. If False, the parent axes' anchor will be unchanged. Defaults to (1.0, 0.5) if vertical; (0.5, 0.0) if horizontal.