8000 Merge pull request #1022 from efiring/contourf_extend · matplotlib/matplotlib@967c15a · GitHub
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Merge pull request #1022 from efiring/contourf_extend
contour: map extended ranges to "under" and "over" values
2 parents 96d1814 + 0c347f3 commit 967c15a

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‎CHANGELOG

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2012-07-24 Contourf handles the extend kwarg by mapping the extended
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ranges outside the normed 0-1 range so that they are
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handled by colormap colors determined by the set_under
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and set_over methods. Previously the extended ranges
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were mapped to 0 or 1 so that the "under" and "over"
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colormap colors were ignored. - EF
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2012-06-24 Make use of mathtext in tick labels configurable - DSD
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2012-06-05 Images loaded through PIL are now ordered correctly - CG

‎doc/api/api_changes.rst

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@@ -14,6 +14,16 @@ For new features that were added to matplotlib, please see
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Changes in 1.2.x
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================
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* In :meth:`~matplotlib.axes.Axes.contourf`, the handling of the *extend*
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kwarg has changed. Formerly, the extended ranges were mapped
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after to 0, 1 after being normed, so that they always corresponded
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to the extreme values of the colormap. Now they are mapped
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outside this range so that they correspond to the special
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colormap values determined by the
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:meth:`~matplotlib.colors.Colormap.set_under` and
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:meth:`~matplotlib.colors.Colormap.set_over` methods, which
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default to the colormap end points.
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* The new rc parameter ``savefig.format`` replaces ``cairo.format`` and
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``savefig.extension``, and sets the default file format used by
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:meth:`matplotlib.figure.Figure.savefig`.

‎examples/pylab_examples/contourf_demo.py

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@@ -1,68 +1,70 @@
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#!/usr/bin/env python
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from pylab import *
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import numpy as np
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import matplotlib.pyplot as plt
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origin = 'lower'
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#origin = 'upper'
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delta = 0.025
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8-
x = y = arange(-3.0, 3.01, delta)
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X, Y = meshgrid(x, y)
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Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
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Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
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x = y = np.arange(-3.0, 3.01, delta)
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X, Y = np.meshgrid(x, y)
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Z1 = plt.mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
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Z2 = plt.mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
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Z = 10 * (Z1 - Z2)
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nr, nc = Z.shape
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# put NaNs in one corner:
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Z[-nr//6:, -nc//6:] = nan
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Z[-nr//6:, -nc//6:] = np.nan
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# contourf will convert these to masked
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21-
Z = ma.array(Z)
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Z = np.ma.array(Z)
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# mask another corner:
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Z[:nr//6, :nc//6] = ma.masked
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Z[:nr//6, :nc//6] = np.ma.masked
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# mask a circle in the middle:
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interior = sqrt((X**2) + (Y**2)) < 0.5
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Z[interior] = ma.masked
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interior = np.sqrt((X**2) + (Y**2)) < 0.5
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Z[interior] = np.ma.masked
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# We are using automatic selection of contour levels;
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# this is usually not such a good idea, because they don't
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# occur on nice boundaries, but we do it here for purposes
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# of illustration.
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CS = contourf(X, Y, Z, 10, # [-1, -0.1, 0, 0.1],
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CS = plt.contourf(X, Y, Z, 10, # [-1, -0.1, 0, 0.1],
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#alpha=0.5,
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cmap=cm.bone,
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cmap=plt.cm.bone,
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origin=origin)
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# Note that in the following, we explicitly pass in a subset of
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# the contour levels used for the filled contours. Alternatively,
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# We could pass in additional levels to provide extra resolution,
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# or leave out the levels kwarg to use all of the original levels.
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44-
CS2 = contour(CS, levels=CS.levels[::2],
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CS2 = plt.contour(CS, levels=CS.levels[::2],
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colors = 'r',
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origin=origin,
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hold='on')
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49-
title('Nonsense (3 masked regions)')
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xlabel('word length anomaly')
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ylabel('sentence length anomaly')
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plt.title('Nonsense (3 masked regions)')
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plt.xlabel('word length anomaly')
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plt.ylabel('sentence length anomaly')
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# Make a colorbar for the ContourSet returned by the contourf call.
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cbar = colorbar(CS)
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cbar = plt.colorbar(CS)
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cbar.ax.set_ylabel('verbosity coefficient')
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# Add the contour line levels to the colorbar
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cbar.add_lines(CS2)
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59-
figure()
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plt.figure()
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# Now make a contour plot with the levels specified,
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# and with the colormap generated automatically from a list
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# of colors.
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levels = [-1.5, -1, -0.5, 0, 0.5, 1]
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CS3 = contourf(X, Y, Z, levels,
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CS3 = plt.contourf(X, Y, Z, levels,
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colors = ('r', 'g', 'b'),
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origin=origin,
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extend='both')
@@ -72,16 +74,34 @@
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CS3.cmap.set_under('yellow')
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CS3.cmap.set_over('cyan')
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75-
CS4 = contour(X, Y, Z, levels,
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CS4 = plt.contour(X, Y, Z, levels,
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colors = ('k',),
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linewidths = (3,),
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origin = origin)
79-
title('Listed colors (3 masked regions)')
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clabel(CS4, fmt = '%2.1f', colors = 'w', fontsize=14)
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plt.title('Listed colors (3 masked regions)')
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plt.clabel(CS4, fmt = '%2.1f', colors = 'w', fontsize=14)
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# Notice that the colorbar command gets all the information it
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# needs from the ContourSet object, CS3.
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colorbar(CS3)
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show()
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plt.colorbar(CS3)
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# Illustrate all 4 possible "extend" settings:
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extends = ["neither", "both", "min", "max"]
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cmap = plt.cm.get_cmap("winter")
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cmap.set_under("magenta")
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cmap.set_over("yellow")
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# Note: contouring simply excludes masked or nan regions, so
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# instead of using the "bad" colormap value for them, it draws
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# nothing at all in them. Therefore the following would have
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# no effect:
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#cmap.set_bad("red")
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fig, axs = plt.subplots(2,2)
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for ax, extend in zip(axs.ravel(), extends):
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cs = ax.contourf(X, Y, Z, levels, cmap=cmap, extend=extend, origin=origin)
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fig.colorbar(cs, ax=ax, shrink=0.9)
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ax.set_title("extend = %s" % extend)
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ax.locator_params(nbins=4)
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plt.show()
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‎lib/matplotlib/contour.py

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Original file line numberDiff line numberDiff line change
@@ -870,10 +870,10 @@ def legend_elements(self, variable_name='x', str_format=str):
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lower = str_format(lower)
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upper = str_format(upper)
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873-
if i == 0 and self.extend in ('lower', 'both'):
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labels.append(r'$%s \leq %s$' % (variable_name, upper, ))
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elif i == n_levels-1 and self.extend in ('upper', 'both'):
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labels.append(r'$%s > %s$' % (variable_name, lower, ))
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if i == 0 and self.extend in ('min', 'both'):
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labels.append(r'$%s \leq %s$' % (variable_name, lower, ))
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elif i == n_levels-1 and self.extend in ('max', 'both'):
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labels.append(r'$%s > %s$' % (variable_name, upper, ))
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else:
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labels.append(r'$%s < %s \leq %s$' % (lower, variable_name, upper))
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else:
@@ -1029,24 +1029,25 @@ def _contour_level_args(self, z, args):
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raise ValueError("Filled contours require at least 2 levels.")
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def _process_levels(self):
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# Color mapping range (norm vmin, vmax) is based on levels.
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self.vmin = np.amin(self.levels)
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self.vmax = np.amax(self.levels)
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# Make a private _levels to include extended regions.
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self._levels = list(self.levels)
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if self.extend in ('both', 'min'):
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self._levels.insert(0, min(self.levels[0],self.zmin) - 1)
10351039
if self.extend in ('both', 'max'):
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self._levels.append(max(self.levels[-1],self.zmax) + 1)
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self._levels = np.asarray(self._levels)
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self.vmin = np.amin(self.levels) # alternative would be self.layers
1039-
self.vmax = np.amax(self.levels)
1040-
if self.extend in ('both', 'min'):
1041-
self.vmin = 2 * self.levels[0] - self.levels[1]
1042-
if self.extend in ('both', 'max'):
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self.vmax = 2 * self.levels[-1] - self.levels[-2]
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if self.filled:
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# layer values are mid-way between levels
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self.layers = 0.5 * (self._levels[:-1] + self._levels[1:])
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# ...except that extended layers must be outside the
1046+
# normed range:
10461047
if self.extend in ('both', 'min'):
1047-
self.layers[0] = 0.5 * (self.vmin + self._levels[1])
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self.layers[0] = -np.inf
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if self.extend in ('both', 'max'):
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self.layers[-1] = 0.5 * (self.vmax + self._levels[-2])
1050+
self.layers[-1] = np.inf
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else:
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self.layers = self.levels # contour: a line is a thin layer
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# Use only original levels--no extended levels
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"""
10661067
self.monochrome = self.cmap.monochrome
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if self.colors is not None:
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# Generate integers for direct indexing.
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i0, i1 = 0, len(self.levels)
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if self.filled:
10701072
i1 -= 1
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# Out of range indices for over and under:
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if self.extend in ('both', 'min'):
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i0 = -1
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if self.extend in ('both', 'max'):
@@ -1080,7 +1083,8 @@ def _process_colors(self):
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self.set_clim(self.vmin, self.vmax)
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if self.extend in ('both', 'max', 'min'):
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self.norm.clip = False
1083-
self.set_array(self.layers)
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self.set_array(self.layers) # Required by colorbar, but not
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# actually used.
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# self.tcolors are set by the "changed" method
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10861090
def _process_linewidths(self):

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