Merge pull request #4771 from AmyTeegarden/legend_demo5

NF - New legend example with line collection

examples/pylab_examples/legend_demo5.py

@@ -0,0 +1,71 @@
+from __future__ import (absolute_import, division,
+                        print_function, unicode_literals)
+import six
+from matplotlib import pyplot as plt
+import numpy as np
+from matplotlib.legend_handler import HandlerLineCollection
+import matplotlib.collections as mcol
+from matplotlib.lines import Line2D
+
+
+class HandlerDashedLines(HandlerLineCollection):
+    """
+    Custom Handler for LineCollection instances.
+    """
+    def create_artists(self, legend, orig_handle,
+                       xdescent, ydescent, width, height, fontsize, trans):
+        # figure out how many lines there are
+        numlines = len(orig_handle.get_segments())
+        xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent,
+                                             width, height, fontsize)
+        leglines = []
+        # divide the vertical space where the lines will go
+        # into equal parts based on the number of lines
+        ydata = ((height) / (numlines + 1)) * np.ones(xdata.shape, float)
+        # for each line, create the line at the proper location
+        # and set the dash pattern
+        for i in range(numlines):
+            legline = Line2D(xdata, ydata * (numlines - i) - ydescent)
+            self.update_prop(legline, orig_handle, legend)
+            # set color, dash pattern, and linewidth to that
+            # of the lines in linecollection
+            try:
+                color = orig_handle.get_colors()[i]
+            except IndexError:
+                color = orig_handle.get_colors()[0]
+            try:
+                dashes = orig_handle.get_dashes()[i]
+            except IndexError:
+                dashes = orig_handle.get_dashes()[0]
+            try:
+                lw = orig_handle.get_linewidths()[i]
+            except IndexError:
+                lw = orig_handle.get_linewidths()[0]
+            if dashes[0] != None:
+                legline.set_dashes(dashes[1])
+            legline.set_color(color)
+            legline.set_transform(trans)
+            legline.set_linewidth(lw)
+            leglines.append(legline)
+        return leglines
+
+x = np.linspace(0, 5, 100)
+
+plt.figure()
+colors = ['red', 'orange', 'yellow', 'green', 'blue']
+styles = ['solid', 'dashed', 'dashed', 'dashed', 'solid']
+lines = []
+for i, color, style in zip(range(5), colors, styles):
+    plt.plot(x, np.sin(x) - .1 * i, c=color, ls=style)
+
+
+# make proxy artists
+# make list of one line -- doesn't matter what the coordinates are
+line = [[(0, 0)]]
+# set up the proxy artist
+lc = mcol.LineCollection(5 * line, linestyles=styles, colors=colors)
+# create the legend
+plt.legend([lc], ['multi-line'], handler_map={type(lc): HandlerDashedLines()},
+           handlelength=2.5, handleheight=3)
+
+plt.show()