## matplotlib-checkins

 SF.net SVN: matplotlib:[8207] trunk/matplotlib/examples/pylab_examples/ multicolored_line.py From: - 2010-03-21 17:43:21 ```Revision: 8207 http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8207&view=rev Author: ryanmay Date: 2010-03-21 17:43:11 +0000 (Sun, 21 Mar 2010) Log Message: ----------- Add multicolored line example based on an example from the scipy.org cookbook cleaned up to use colormaps. Added Paths: ----------- trunk/matplotlib/examples/pylab_examples/multicolored_line.py Added: trunk/matplotlib/examples/pylab_examples/multicolored_line.py =================================================================== --- trunk/matplotlib/examples/pylab_examples/multicolored_line.py (rev 0) +++ trunk/matplotlib/examples/pylab_examples/multicolored_line.py 2010-03-21 17:43:11 UTC (rev 8207) @@ -0,0 +1,36 @@ +#!/usr/bin/env python +''' +Color parts of a line based on its properties, e.g., slope. +''' +import numpy as np +import matplotlib.pyplot as plt +from matplotlib.collections import LineCollection +from matplotlib.colors import ListedColormap, BoundaryNorm + +x = np.linspace(0, 3 * np.pi, 500) +y = np.sin(x) +z = np.cos(0.5 * (x[:-1] + x[1:])) # first derivative + +# Create a colormap for red, green and blue and a norm to color +# f' < -0.5 red, f' > 0.5 blue, and the rest green +cmap = ListedColormap(['r', 'g', 'b']) +norm = BoundaryNorm([-1, -0.5, 0.5, 1], cmap.N) + +# Create a set of line segments so that we can color them individually +# This creates the points as a N x 1 x 2 array so that we can stack points +# together easily to get the segments. The segments array for line collection +# needs to be numlines x points per line x 2 (x and y) +points = np.array([x, y]).T.reshape(-1, 1, 2) +segments = np.concatenate([points[:-1], points[1:]], axis=1) + +# Create the line collection object, setting the colormapping parameters. +# Have to set the actual values used for colormapping separately. +lc = LineCollection(segments, cmap=cmap, norm=norm) +lc.set_array(z) +lc.set_linewidth(3) +plt.gca().add_collection(lc) + +plt.xlim(x.min(), x.max()) +plt.ylim(-1.1, 1.1) +plt.show() + This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site. ```
 SF.net SVN: matplotlib:[8208] trunk/matplotlib/examples/pylab_examples/ multicolored_line.py From: - 2010-03-21 19:28:00 ```Revision: 8208 http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8208&view=rev Author: ryanmay Date: 2010-03-21 19:27:52 +0000 (Sun, 21 Mar 2010) Log Message: ----------- Add second example from scipy cookbook to this script, showing the use of more traditional colormapping. Modified Paths: -------------- trunk/matplotlib/examples/pylab_examples/multicolored_line.py Modified: trunk/matplotlib/examples/pylab_examples/multicolored_line.py =================================================================== --- trunk/matplotlib/examples/pylab_examples/multicolored_line.py 2010-03-21 17:43:11 UTC (rev 8207) +++ trunk/matplotlib/examples/pylab_examples/multicolored_line.py 2010-03-21 19:27:52 UTC (rev 8208) @@ -28,9 +28,26 @@ lc = LineCollection(segments, cmap=cmap, norm=norm) lc.set_array(z) lc.set_linewidth(3) + +fig1 = plt.figure() plt.gca().add_collection(lc) - plt.xlim(x.min(), x.max()) plt.ylim(-1.1, 1.1) + +# Now do a second plot coloring the curve using a continuous colormap +t = np.linspace(0, 10, 200) +x = np.cos(np.pi * t) +y = np.sin(t) +points = np.array([x, y]).T.reshape(-1, 1, 2) +segments = np.concatenate([points[:-1], points[1:]], axis=1) + +lc = LineCollection(segments, cmap=plt.get_cmap('copper'), + norm=plt.Normalize(0, 10)) +lc.set_array(t) +lc.set_linewidth(3) + +fig2 = plt.figure() +plt.gca().add_collection(lc) +plt.xlim(-1, 1) +plt.ylim(-1, 1) plt.show() - This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site. ```