@@ -1766,14 +1766,42 @@ def _initialize_x_y(self, z):
17661766 are not given explicitly via *levels*.
17671767 Defaults to `~.ticker.MaxNLocator`.
17681768
1769- extend : {'neither', 'both', 'min', 'max'}, optional
1770- Unless this is 'neither', contour levels are automatically
1771- added to one or both ends of the range so that all data
1772- are included. These added ranges are then mapped to the
1773- special colormap values which default to the ends of the
1774- colormap range, but can be set via
1775- :meth:`matplotlib.colors.Colormap.set_under` and
1776- :meth:`matplotlib.colors.Colormap.set_over` methods.
1769+ extend : {'neither', 'both', 'min', 'max'}, optional, default:\
1770+
1771+ Determines the ``contourf``-coloring of values that are outside the
1772+ *levels* range.
1773+
1774+ If 'neither', values outside the *levels* range are not colored.
1775+ If 'min', 'max' or 'both', color the values below, above or below
1776+ and above the *levels* range.
1777+
1778+ Values below ``min(levels)`` and above ``max(levels)`` are mapped
1779+ to the under/over values of the `.Colormap`. Note, that most
1780+ colormaps do not have dedicated colors for these by default, so
1781+ that the over and under values are the edge values of the colormap.
1782+ You may want to set these values explicitly using
1783+ `.Colormap.set_under` and `.Colormap.set_over`.
1784+
1785+ .. note::
1786+
1787+ An exising `.QuadContourSet` does not get notified if
1788+ properties of its colormap are changed. Therefore, an explicit
1789+ call `.QuadContourSet.changed()` is needed after modifying the
1790+ colormap. The explicit call can be left out, if a colorbar is
1791+ assigned to the `.QuadContourSet` because it interally calls
1792+ `.QuadContourSet.changed()`.
1793+
1794+ Example::
1795+
1796+ x = np.arange(1, 10)
1797+ y = x.reshape(-1, 1)
1798+ h = x * y
1799+
1800+ cs = plt.contourf(h, levels=[10, 30, 50],
1801+ colors=['#808080', '#A0A0A0', '#C0C0C0'], extend='both')
1802+ cs.cmap.set_over('red')
1803+ cs.cmap.set_under('blue')
1804+ cs.changed()
17771805
17781806 xunits, yunits : registered units, optional
17791807 Override axis units by specifying an instance of a