Cleanup integral_demo

tonysyu · tonysyu · commit edce62b97de2 · 2012-12-22T22:51:02.000-08:00
diff --git a/examples/showcase/integral_demo.py b/examples/showcase/integral_demo.py
@@ -1,39 +1,51 @@
 """
 Plot demonstrating the integral as the area under a curve.
+
+Although this is a simple example, it demonstrates some important tweaks:
+
+    * A simple line plot with custom color and line width.
+    * A shaded region created using a Polygon patch.
+    * A text label with mathtext rendering.
+    * figtext calls to label the x- and y-axes.
+    * Use of axis spines to hide the top and right spines.
+    * Custom tick placement and labels.
 """
 import numpy as np
 import matplotlib.pyplot as plt
 from matplotlib.patches import Polygon
 
+
 def func(x):
-    return (x-3)*(x-5)*(x-7)+85
+    return (x - 3) * (x - 5) * (x - 7) + 85
 
-fig, ax = plt.subplots()
 
-a, b = 2, 9 # integral area
+a, b = 2, 9 # integral limits
 x = np.linspace(0, 10)
 y = func(x)
+
+fig, ax = plt.subplots()
 plt.plot(x, y, 'r', linewidth=2)
+plt.ylim(ymin=0)
 
-# make the shaded region
+# Make the shaded region
 ix = np.linspace(a, b)
 iy = func(ix)
-verts = [(a,0)] + list(zip(ix,iy)) + [(b,0)]
+verts = [(a, 0)] + list(zip(ix, iy)) + [(b, 0)]
 poly = Polygon(verts, facecolor='0.9', edgecolor='0.5')
 ax.add_patch(poly)
 
-plt.text(0.5 * (a + b), 30,
-         r"$\int_a^b f(x)\mathrm{d}x$", horizontalalignment='center',
-         fontsize=20)
+plt.text(0.5 * (a + b), 30, r"$\int_a^b f(x)\mathrm{d}x$",
+         horizontalalignment='center', fontsize=20)
 
-plt.axis([0,10, 0, 180])
 plt.figtext(0.9, 0.05, '$x$')
 plt.figtext(0.1, 0.9, '$y$')
 
 ax.spines['right'].set_visible(False)
 ax.spines['top'].set_visible(False)
-ax.set_xticks((a,b))
-ax.set_xticklabels(('$a$','$b$'))
+ax.xaxis.set_ticks_position('bottom')
+
+ax.set_xticks((a, b))
+ax.set_xticklabels(('$a$', '$b$'))
 ax.set_yticks([])
 
 plt.show()
