added intro, cleaned up code to PEP8 std

examples/mayavi/interactive/realguisuperquad.py

@@ -1,24 +1,26 @@
-#from enthought.mayavi import mlab
-import numpy as np
-#from scipy.special import sph_harm
+"""
+This example uses MayaVi to show the evolution of a superquadric
+(http://en.wikipedia.org/wiki/Superquadrics), which are ellipsoidal surfaces parametrised
+by two parameters,\alpha and \beta. The equations that are used to determine the superquadric are 
+(in spherical-polar coordinates):
 
-def fexp(x,p):
-    """a different kind of exponentiation"""
-    return (np.sign(x)*(np.abs(x)**p))
+  \(x = A(\sin^{\alpha}(\phi)*\cos^{\beta}(\theta))\)
+  \(y = B(\sin^{\alpha}(\phi)*\sin^{\beta}(\theta))\)
+  \(z = C(\cos^{\alpha}(\phi))\)
 
-def tens_fld(A,B,C,P,Q):
-    """this module plots superquadratic surfaces with the given parameters"""
-   # mlab.figure(fgcolor=(1,1,1), bgcolor=(0,0,0))
-    phi, theta = np.mgrid[0:np.pi:80j, 0:2*np.pi:80j]
-    x       =A*(fexp(np.sin(phi),P)) *(fexp(np.cos(theta),Q))
-    y       =B*(fexp(np.sin(phi),P)) *(fexp(np.sin(theta),Q))
-    z       =C*(fexp(np.cos(phi),P))
-    #s       = sph_harm(1, 1, theta, phi).real
-    return x , y , z 
-    #mlab.mesh(x, y, z, colormap='copper')
+Note that when we set A=B=C=r, and \alpha =  \beta = 1, we get the 
+equation for a sphere in spherical polar coordinate.
+
+Use the controls at the bottom of the plot to adjust \alpha and \beta,
+and watch as the figure transforms accordingly!
 
-    #mlab.show()
+"""
 
+# Author: Pratik Mallya <[email protected]>
+# Copyright (c) 2008-2013, Enthought, Inc.
+# License: BSD Style.
+
+import numpy as np
 from enthought.traits.api import HasTraits, Range, Instance, \
                     on_trait_change
 from enthought.traits.ui.api import View, Item, HGroup
@@ -28,26 +30,39 @@ def tens_fld(A,B,C,P,Q):
 from enthought.mayavi.core.ui.mayavi_scene import MayaviScene
 
 
+def fexp(x,p):
+    """a different kind of exponentiation"""
+    return (np.sign(x) * (np.abs(x)**p))
+
+def tens_fld(A,B,C,P,Q):
+    """this module plots superquadratic surfaces with the given parameters"""
+    phi, theta = np.mgrid[0:np.pi:80j, 0:2*np.pi:80j]
+    x = A * (fexp(np.sin(phi),P)) * (fexp(np.cos(theta),Q))
+    y = B * (fexp(np.sin(phi),P)) * (fexp(np.sin(theta),Q))
+    z = C * (fexp(np.cos(phi),P))
+    return x , y , z 
+
+
 class Visualization(HasTraits):
-    alpha = Range(0.0, 4.0,  1.0/4)
-    beta  = Range(0.0, 4.0,  1.0/4)
-    scene      = Instance(MlabSceneModel, ())
+    alpha = Range(0.0, 4.0, 1.0/4)
+    beta  = Range(0.0, 4.0, 1.0/4)
+    scene = Instance(MlabSceneModel, ())
 
     def __init__(self):
         # Do not forget to call the parent's __init__
         HasTraits.__init__(self)
-        x, y, z, = tens_fld(1,1,1,self.beta, self.alpha)
+        x, y, z, = tens_fld(1, 1, 1, self.beta, self.alpha)
         self.plot = self.scene.mlab.mesh(x, y, z, colormap='copper', representation='surface')
 
     @on_trait_change('beta,alpha')
     def update_plot(self):
-        x, y, z, = tens_fld(1,1,1,self.beta, self.alpha)
-        self.plot.mlab_source.set(x=x, y=y, z=z)
+        x, y, z, = tens_fld(1, 1, 1, self.beta, self.alpha)
+        self.plot.mlab_source.set(x = x, y = y, z = z)
 
 
     # the layout of the dialog created
-    view = View(Item('scene', editor=SceneEditor(scene_class=MayaviScene),
-                    height=750, width=750, show_label=False),
+    view = View(Item('scene', editor = SceneEditor(scene_class=MayaviScene),
+                    height = 750, width=750, show_label=False),
                 HGroup(
                         '_', 'beta', 'alpha',
                     ),