Make viewlims demo more interesting by using events to regenerate a fractal.

dopplershift · dopplershift · commit 49bfcca00691 · 2009-02-12T21:20:09.000Z
svn path=/branches/v0_98_5_maint/; revision=6909
diff --git a/examples/event_handling/viewlims.py b/examples/event_handling/viewlims.py
@@ -12,16 +12,58 @@ def __call__(self, ax):
         self.set_bounds(*ax.viewLim.bounds)
         ax.figure.canvas.draw_idle()
 
-x = np.linspace(-3., 3., 20)
-y = np.linspace(-3., 3., 20).reshape(-1,1)
-Z = (1- x/2 + x**5 + y**3)*np.exp(-x**2-y**2)
+# A class that will regenerate a fractal set as we zoom in, so that you
+# can actually see the increasing detail.  A box in the left panel will show
+# the area to which we are zoomed.
+class MandlebrotDisplay(object):
+    def __init__(self, h=500, w=500, niter=50, radius=2., power=2):
+        self.height = h
+        self.width = w
+        self.niter = niter
+        self.radius = radius
+        self.power = power
+
+    def __call__(self, xstart, xend, ystart, yend):
+        self.x = np.linspace(xstart, xend, self.width)
+        self.y = np.linspace(ystart, yend, self.height).reshape(-1,1)
+        c = self.x + 1.0j * self.y
+        threshold_time = np.zeros((self.height, self.width))
+        z = np.zeros(threshold_time.shape, dtype=np.complex)
+        mask = np.ones(threshold_time.shape, dtype=np.bool)
+        for i in xrange(self.niter):
+            z[mask] = z[mask]**self.power + c[mask]
+            mask = (np.abs(z) < self.radius)
+            threshold_time += mask
+        return threshold_time
+
+    def ax_update(self, ax):
+        ax.set_autoscale_on(False) # Otherwise, infinite loop
+
+        #Get the number of points from the number of pixels in the window
+        dims = ax.axesFrame.get_window_extent().bounds
+        self.width = int(dims[2] + 0.5)
+        self.height = int(dims[2] + 0.5)
+
+        #Get the range for the new area
+        xstart,ystart,xdelta,ydelta = ax.viewLim.bounds
+        xend = xstart + xdelta
+        yend = ystart + ydelta
+
+        # Update the image object with our new data and extent
+        im = ax.images[-1]
+        im.set_data(self.__call__(xstart, xend, ystart, yend))
+        im.set_extent((xstart, xend, ystart, yend))
+        ax.figure.canvas.draw_idle()
+
+md = MandlebrotDisplay()
+Z = md(-2., 0.5, -1.25, 1.25)
 
 fig = plt.figure()
 ax1 = fig.add_subplot(1, 2, 1)
-ax1.pcolor(x, y, Z)
+ax1.imshow(Z, origin='lower', extent=(md.x.min(), md.x.max(), md.y.min(), md.y.max()))
 
 ax2 = fig.add_subplot(1, 2, 2)
-ax2.pcolor(x, y, Z)
+ax2.imshow(Z, origin='lower', extent=(md.x.min(), md.x.max(), md.y.min(), md.y.max()))
 
 rect = UpdatingRect([0, 0], 0, 0, facecolor='None', edgecolor='black')
 rect.set_bounds(*ax2.viewLim.bounds)
@@ -31,4 +73,7 @@ def __call__(self, ax):
 ax2.callbacks.connect('xlim_changed', rect)
 ax2.callbacks.connect('ylim_changed', rect)
 
+ax2.callbacks.connect('xlim_changed', md.ax_update)
+ax2.callbacks.connect('ylim_changed', md.ax_update)
+
 plt.show()
