diff --git a/doc/api/api_changes.rst b/doc/api/api_changes.rst
index a077f851101f..bc65dcfb2a1f 100644
--- a/doc/api/api_changes.rst
+++ b/doc/api/api_changes.rst
@@ -51,6 +51,9 @@ Changes in 1.2.x
matplotlib axes by providing a ``_as_mpl_axes`` method. See
:ref:`adding-new-scales` for more detail.
+* A new keyword *extendfrac* in :meth:`~matplotlib.pyplot.colorbar` and
+ :class:`~matplotlib.colorbar.ColorbarBase` allows one to control the size of
+ the triangular minimum and maximum extensions on colorbars.
Changes in 1.1.x
================
diff --git a/doc/users/whats_new.rst b/doc/users/whats_new.rst
index f18fc2f1a5c5..83b707a58e68 100644
--- a/doc/users/whats_new.rst
+++ b/doc/users/whats_new.rst
@@ -26,6 +26,37 @@ Damon McDougall added a new plotting method for the
.. plot:: mpl_examples/mplot3d/trisurf3d_demo.py
+Control the lengths of colorbar extensions
+------------------------------------------
+
+Andrew Dawson added a new keyword argument *extendfrac* to
+:meth:`~matplotlib.pyplot.colorbar` to control the length of
+minimum and maximum colorbar extensions.
+
+.. plot::
+
+ import matplotlib.pyplot as plt
+ import numpy as np
+
+ x = y = np.linspace(0., 2*np.pi, 100)
+ X, Y = np.meshgrid(x, y)
+ Z = np.cos(X) * np.sin(0.5*Y)
+
+ clevs = [-.75, -.5, -.25, 0., .25, .5, .75]
+ cmap = plt.cm.get_cmap(name='jet', lut=8)
+
+ ax1 = plt.subplot(211)
+ cs1 = plt.contourf(x, y, Z, clevs, cmap=cmap, extend='both')
+ cb1 = plt.colorbar(orientation='horizontal', extendfrac=None)
+ cb1.set_label('Default length colorbar extensions')
+
+ ax2 = plt.subplot(212)
+ cs2 = plt.contourf(x, y, Z, clevs, cmap=cmap, extend='both')
+ cb2 = plt.colorbar(orientation='horizontal', extendfrac='auto')
+ cb2.set_label('Custom length colorbar extensions')
+
+ plt.show()
+
.. _whats-new-1-1:
new in matplotlib-1.1
diff --git a/examples/api/colorbar_only.py b/examples/api/colorbar_only.py
index e071e1b4a156..0e1837e95f19 100644
--- a/examples/api/colorbar_only.py
+++ b/examples/api/colorbar_only.py
@@ -6,8 +6,9 @@
# Make a figure and axes with dimensions as desired.
fig = pyplot.figure(figsize=(8,3))
-ax1 = fig.add_axes([0.05, 0.65, 0.9, 0.15])
-ax2 = fig.add_axes([0.05, 0.25, 0.9, 0.15])
+ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
+ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])
+ax3 = fig.add_axes([0.05, 0.15, 0.9, 0.15])
# Set the colormap and norm to correspond to the data for which
# the colorbar will be used.
@@ -47,5 +48,27 @@
orientation='horizontal')
cb2.set_label('Discrete intervals, some other units')
+# The third example illustrates the use of custom length colorbar
+# extensions, used on a colorbar with discrete intervals.
+cmap = mpl.colors.ListedColormap([[0., .4, 1.], [0., .8, 1.],
+ [1., .8, 0.], [1., .4, 0.]])
+cmap.set_over((1., 0., 0.))
+cmap.set_under((0., 0., 1.))
+
+bounds = [-1., -.5, 0., .5, 1.]
+norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
+cb3 = mpl.colorbar.ColorbarBase(ax3, cmap=cmap,
+ norm=norm,
+ boundaries=[-10]+bounds+[10],
+ extend='both',
+ # Make the length of each extension
+ # the same as the length of the
+ # interior colors:
+ extendfrac='auto',
+ ticks=bounds,
+ spacing='uniform',
+ orientation='horizontal')
+cb3.set_label('Custom extension lengths, some other units')
+
pyplot.show()
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
index 0c4583f465f0..5eb9e779ced2 100644
--- a/lib/matplotlib/__init__.py
+++ b/lib/matplotlib/__init__.py
@@ -992,7 +992,8 @@ def tk_window_focus():
'matplotlib.tests.test_text',
'matplotlib.tests.test_tightlayout',
'matplotlib.tests.test_delaunay',
- 'matplotlib.tests.test_legend'
+ 'matplotlib.tests.test_legend',
+ 'matplotlib.tests.test_colorbar',
]
def test(verbosity=1):
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
index 5f03f568feb5..2f8a72092300 100644
--- a/lib/matplotlib/colorbar.py
+++ b/lib/matplotlib/colorbar.py
@@ -59,13 +59,29 @@
colormap_kw_doc = '''
- =========== ====================================================
+ ============ ====================================================
Property Description
- =========== ====================================================
+ ============ ====================================================
*extend* [ 'neither' | 'both' | 'min' | 'max' ]
If not 'neither', make pointed end(s) for out-of-
range values. These are set for a given colormap
using the colormap set_under and set_over methods.
+ *extendfrac* [ *None* | 'auto' | length | lengths ]
+ If set to *None*, both the minimum and maximum
+ triangular colorbar extensions with have a length of
+ 5% of the interior colorbar length (this is the
+ default setting). If set to 'auto', makes the
+ triangular colorbar extensions the same lengths as
+ the interior boxes (when *spacing* is set to
+ 'uniform') or the same lengths as the respective
+ adjacent interior boxes (when *spacing* is set to
+ 'proportional'). If a scalar, indicates the length
+ of both the minimum and maximum triangular colorbar
+ extensions as a fraction of the interior colorbar
+ length. A two-element sequence of fractions may also
+ be given, indicating the lengths of the minimum and
+ maximum colorbar extensions respectively as a
+ fraction of the interior colorbar length.
*spacing* [ 'uniform' | 'proportional' ]
Uniform spacing gives each discrete color the same
space; proportional makes the space proportional to
@@ -82,7 +98,7 @@
given instead.
*drawedges* [ False | True ] If true, draw lines at color
boundaries.
- =========== ====================================================
+ ============ ====================================================
The following will probably be useful only in the context of
indexed colors (that is, when the mappable has norm=NoNorm()),
@@ -221,6 +237,7 @@ def __init__(self, ax, cmap=None,
format=None,
drawedges=False,
filled=True,
+ extendfrac=None,
):
self.ax = ax
self._patch_ax()
@@ -236,6 +253,7 @@ def __init__(self, ax, cmap=None,
self.orientation = orientation
self.drawedges = drawedges
self.filled = filled
+ self.extendfrac = extendfrac
self.solids = None
self.lines = None
self.outline = None
@@ -616,6 +634,35 @@ def _extended_N(self):
N += 1
return N
+ def _get_extension_lengths(self, frac, automin, automax, default=0.05):
+ '''
+ Get the lengths of colorbar extensions.
+
+ A helper method for _uniform_y and _proportional_y.
+ '''
+ # Set the default value.
+ extendlength = np.array([default, default])
+ if isinstance(frac, str):
+ if frac.lower() == 'auto':
+ # Use the provided values when 'auto' is required.
+ extendlength[0] = automin
+ extendlength[1] = automax
+ else:
+ # Any other string is invalid.
+ raise ValueError('invalid value for extendfrac')
+ elif frac is not None:
+ try:
+ # Try to set min and max extension fractions directly.
+ extendlength[:] = frac
+ # If frac is a sequence contaning None then NaN may
+ # be encountered. This is an error.
+ if np.isnan(extendlength).any():
+ raise ValueError()
+ except (TypeError, ValueError):
+ # Raise an error on encountering an invalid value for frac.
+ raise ValueError('invalid value for extendfrac')
+ return extendlength
+
def _uniform_y(self, N):
'''
Return colorbar data coordinates for *N* uniformly
@@ -624,16 +671,19 @@ def _uniform_y(self, N):
if self.extend == 'neither':
y = np.linspace(0, 1, N)
else:
+ automin = automax = 1. / (N - 1.)
+ extendlength = self._get_extension_lengths(self.extendfrac,
+ automin, automax, default=0.05)
if self.extend == 'both':
y = np.zeros(N + 2, 'd')
- y[0] = -0.05
- y[-1] = 1.05
+ y[0] = 0. - extendlength[0]
+ y[-1] = 1. + extendlength[1]
elif self.extend == 'min':
y = np.zeros(N + 1, 'd')
- y[0] = -0.05
+ y[0] = 0. - extendlength[0]
else:
y = np.zeros(N + 1, 'd')
- y[-1] = 1.05
+ y[-1] = 1. + extendlength[1]
y[self._inside] = np.linspace(0, 1, N)
return y
@@ -648,10 +698,27 @@ def _proportional_y(self):
y = y / (self._boundaries[-1] - self._boundaries[0])
else:
y = self.norm(self._boundaries.copy())
- if self._extend_lower():
- y[0] = -0.05
- if self._extend_upper():
- y[-1] = 1.05
+ if self.extend == 'min':
+ # Exclude leftmost interval of y.
+ clen = y[-1] - y[1]
+ automin = (y[2] - y[1]) / clen
+ automax = (y[-1] - y[-2]) / clen
+ elif self.extend == 'max':
+ # Exclude rightmost interval in y.
+ clen = y[-2] - y[0]
+ automin = (y[1] - y[0]) / clen
+ automax = (y[-2] - y[-3]) / clen
+ else:
+ # Exclude leftmost and rightmost intervals in y.
+ clen = y[-2] - y[1]
+ automin = (y[2] - y[1]) / clen
+ automax = (y[-2] - y[-3]) / clen
+ extendlength = self._get_extension_lengths(self.extendfrac,
+ automin, automax, default=0.05)
+ if self.extend in ('both', 'min'):
+ y[0] = 0. - extendlength[0]
+ if self.extend in ('both', 'max'):
+ y[-1] = 1. + extendlength[1]
yi = y[self._inside]
norm = colors.Normalize(yi[0], yi[-1])
y[self._inside] = norm(yi)
diff --git a/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_proportional.png b/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_proportional.png
new file mode 100644
index 000000000000..e531db31bb1b
Binary files /dev/null and b/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_proportional.png differ
diff --git a/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_uniform.png b/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_uniform.png
new file mode 100644
index 000000000000..d8c7b87aec06
Binary files /dev/null and b/lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_extensions_uniform.png differ
diff --git a/lib/matplotlib/tests/test_colorbar.py b/lib/matplotlib/tests/test_colorbar.py
new file mode 100644
index 000000000000..541b2b7fc803
--- /dev/null
+++ b/lib/matplotlib/tests/test_colorbar.py
@@ -0,0 +1,61 @@
+from matplotlib import rcParams, rcParamsDefault
+from matplotlib.testing.decorators import image_comparison
+import matplotlib.pyplot as plt
+from matplotlib.colors import BoundaryNorm
+from matplotlib.cm import get_cmap
+from matplotlib.colorbar import ColorbarBase
+
+
+def _colorbar_extensions(spacing):
+
+ # Create a color map and specify the levels it represents.
+ cmap = get_cmap("RdBu", lut=5)
+ clevs = [-5., -2.5, -.5, .5, 1.5, 3.5]
+
+ # Define norms for the color maps.
+ norms = dict()
+ norms['neither'] = BoundaryNorm(clevs, len(clevs)-1)
+ norms['min'] = BoundaryNorm([-10]+clevs[1:], len(clevs)-1)
+ norms['max'] = BoundaryNorm(clevs[:-1]+[10], len(clevs)-1)
+ norms['both'] = BoundaryNorm([-10]+clevs[1:-1]+[10], len(clevs)-1)
+
+ # Create a figure and adjust whitespace for subplots.
+ fig = plt.figure()
+ fig.subplots_adjust(hspace=.6)
+
+ for i, extension_type in enumerate(('neither', 'min', 'max', 'both')):
+ # Get the appropriate norm and use it to get colorbar boundaries.
+ norm = norms[extension_type]
+ boundaries = values = norm.boundaries
+ for j, extendfrac in enumerate((None, 'auto', 0.1)):
+ # Create a subplot.
+ cax = fig.add_subplot(12, 1, i*3+j+1)
+ # Turn off text and ticks.
+ for item in cax.get_xticklabels() + cax.get_yticklabels() +\
+ cax.get_xticklines() + cax.get_yticklines():
+ item.set_visible(False)
+ # Generate the colorbar.
+ cb = ColorbarBase(cax, cmap=cmap, norm=norm,
+ boundaries=boundaries, values=values,
+ extend=extension_type, extendfrac=extendfrac,
+ orientation='horizontal', spacing=spacing)
+
+ # Return the figure to the caller.
+ return fig
+
+
+@image_comparison(
+ baseline_images=['colorbar_extensions_uniform', 'colorbar_extensions_proportional'],
+ extensions=['png'])
+def test_colorbar_extensions():
+ # Use default params so .matplotlibrc doesn't cause the test to fail.
+ rcParams.update(rcParamsDefault)
+ # Create figures for uniform and proportionally spaced colorbars.
+ fig1 = _colorbar_extensions('uniform')
+ fig2 = _colorbar_extensions('proportional')
+
+
+if __name__ == '__main__':
+ import nose
+ nose.runmodule(argv=['-s', '--with-doctest'], exit=False)
+
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