Merge pull request matplotlib#13147 from timhoffm/doc-joinstyle

Extend joinstyle example

Author: dstansby

examples/lines_bars_and_markers/joinstyle.py

@@ -1,11 +1,26 @@
 """
-===========
-Join styles
-===========
+==========================
+Join styles and cap styles
+==========================
+
+This example demonstrates the available join styles and cap styles.
+
+Both are used in `.Line2D` and various ``Collections`` from
+`matplotlib.collections` as well as some functions that create these, e.g.
+`~matplotlib.pyplot.plot`.
 
-Illustrate the three different join styles.
 """
 
+#############################################################################
+#
+# Join styles
+# """""""""""
+#
+# Join styles define how the connection between two line segments is drawn.
+#
+# See the respective ``solid_joinstyle``, ``dash_joinstyle`` or ``joinstyle``
+# parameters.
+
 import numpy as np
 import matplotlib.pyplot as plt
 
@@ -14,25 +29,56 @@ def plot_angle(ax, x, y, angle, style):
     phi = np.radians(angle)
     xx = [x + .5, x, x + .5*np.cos(phi)]
     yy = [y, y, y + .5*np.sin(phi)]
-    ax.plot(xx, yy, lw=8, color='tab:blue', solid_joinstyle=style)
-    ax.plot(xx[1:], yy[1:], lw=1, color='black')
-    ax.plot(xx[1::-1], yy[1::-1], lw=1, color='black')
-    ax.plot(xx[1:2], yy[1:2], 'o', color='tab:red', markersize=3)
-    ax.text(x, y + .2, '%.0f degrees' % angle)
+    ax.plot(xx, yy, lw=12, color='tab:blue', solid_joinstyle=style)
+    ax.plot(xx, yy, lw=1, color='black')
+    ax.plot(xx[1], yy[1], 'o', color='tab:red', markersize=3)
 
 
-fig, ax = plt.subplots()
+fig, ax = plt.subplots(figsize=(8, 6))
 ax.set_title('Join style')
 
-for x, style in enumerate((('miter', 'round', 'bevel'))):
+for x, style in enumerate(['miter', 'round', 'bevel']):
     ax.text(x, 5, style)
-    for i in range(5):
-        plot_angle(ax, x, i, pow(2.0, 3 + i), style)
+    for y, angle in enumerate([20, 45, 60, 90, 120]):
+        plot_angle(ax, x, y, angle, style)
+        if x == 0:
+            ax.text(-1.3, y, f'{angle} degrees')
+ax.text(1, 4.7, '(default)')
 
-ax.set_xlim(-.5, 2.75)
+ax.set_xlim(-1.5, 2.75)
 ax.set_ylim(-.5, 5.5)
+ax.xaxis.set_visible(False)
+ax.yaxis.set_visible(False)
 plt.show()
 
+
+#############################################################################
+#
+# Cap styles
+# """"""""""
+#
+# Cap styles define how the the end of a line is drawn.
+#
+# See the respective ``solid_capstyle``, ``dash_capstyle`` or ``capstyle``
+# parameters.
+
+fig, ax = plt.subplots(figsize=(8, 2))
+ax.set_title('Cap style')
+
+for x, style in enumerate(['butt', 'round', 'projecting']):
+    ax.text(x, 1, style)
+    xx = [x, x+0.5]
+    yy = [0, 0]
+    ax.plot(xx, yy, lw=12, color='tab:blue', solid_capstyle=style)
+    ax.plot(xx, yy, lw=1, color='black')
+    ax.plot(xx, yy, 'o', color='tab:red', markersize=3)
+ax.text(2, 0.7, '(default)')
+
+ax.set_ylim(-.5, 1.5)
+ax.xaxis.set_visible(False)
+ax.yaxis.set_visible(False)
+
+
 #############################################################################
 #
 # ------------