pyplot: add pause() function for crude animation

examples/pylab_examples/animation_demo.py

@@ -0,0 +1,30 @@
+"""
+Pyplot animation example.
+
+The method shown here is only for very simple, low-performance
+use.  For more demanding applications, look at the animation
+module and the examples that use it.
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+x = np.arange(6)
+y = np.arange(5)
+z = x * y[:,np.newaxis]
+
+for i in xrange(5):
+    if i==0:
+        p = plt.imshow(z)
+        fig = plt.gcf()
+        plt.clim()   # clamp the color limits
+        plt.title("Boring slide show")
+    else:
+        z = z + 2
+        p.set_data(z)
+
+    print "step", i
+    plt.pause(0.5)
+
+
+

lib/matplotlib/pylab.py

@@ -61,6 +61,7 @@
   loglog   - a log log plot
   matshow  - display a matrix in a new figure preserving aspect
   margins  - set margins used in autoscaling
+  pause    - pause for a specified interval
   pcolor   - make a pseudocolor plot
   pcolormesh - make a pseudocolor plot using a quadrilateral mesh
   pie      - make a pie chart

lib/matplotlib/pyplot.py

@@ -146,6 +146,41 @@ def ion():
     'Turn interactive mode on.'
     matplotlib.interactive(True)
 
+def pause(interval):
+    """
+    Pause for *interval* seconds.
+
+    If there is an active figure it will be updated and displayed,
+    and the gui event loop will run during the pause.
+
+    If there is no active figure, or if a non-interactive backend
+    is in use, this executes time.sleep(interval).
+
+    This can be used for crude animation. For more complex
+    animation, see :mod:`matplotlib.animation`.
+
+    """
+    backend = rcParams['backend']
+    if backend in _interactive_bk:
+        figManager = _pylab_helpers.Gcf.get_active()
+        if figManager is not None:
+            canvas = figManager.canvas
+            canvas.draw()
+            was_interactive = isinteractive()
+            if not was_interactive:
+                ion()
+                show()
+            canvas.start_event_loop(interval)
+            if not was_interactive:
+                ioff()
+            return
+
+    # No on-screen figure is active, so sleep() is all we need.
+    import time
+    time.sleep(interval)
+
+
+
 @docstring.copy_dedent(matplotlib.rc)
 def rc(*args, **kwargs):
     matplotlib.rc(*args, **kwargs)
@@ -958,7 +993,7 @@ def subplot_tool(targetfig=None):
 
 def tight_layout(pad=1.2, h_pad=None, w_pad=None):
     """Adjust subplot parameters to give specified padding.
-    
+
     Parameters
     ----------
     pad : float