Backport PR #9900: DOC: Updates multiprocessing example.

dopplershift · MeeseeksDev[bot] · commit db1617547a64 · 2017-12-01T22:53:56.000Z
diff --git a/examples/misc/multiprocess_sgskip.py b/examples/misc/multiprocess_sgskip.py
@@ -3,27 +3,37 @@
 Multiprocess
 ============
 
-Demo of using multiprocessing for generating data in one process and plotting
-in another.
+Demo of using multiprocessing for generating data in one process and
+plotting in another.
 
 Written by Robert Cimrman
 """
-
 from __future__ import print_function
-from six.moves import input
 
 import time
-from multiprocessing import Process, Pipe
 import numpy as np
 
-import matplotlib
-matplotlib.use('GtkAgg')
+from multiprocessing import Process, Pipe
+
+# This example will likely not work with the native OSX backend.
+# Uncomment the following lines to use the qt5 backend instead.
+#
+# import matplotlib
+# matplotlib.use('qt5Agg')
+
 import matplotlib.pyplot as plt
-import gobject
 
 # Fixing random state for reproducibility
 np.random.seed(19680801)
 
+###############################################################################
+#
+# Processing Class
+# ================
+#
+# This class plots data it recieves from a pipe.
+#
+
 
 class ProcessPlotter(object):
     def __init__(self):
@@ -55,18 +65,36 @@ def __call__(self, pipe):
 
         self.pipe = pipe
         self.fig, self.ax = plt.subplots()
-        self.gid = gobject.timeout_add(1000, self.poll_draw())
+        timer = self.fig.canvas.new_timer(interval=1000)
+        timer.add_callback(self.poll_draw())
+        timer.start()
 
         print('...done')
         plt.show()
 
+###############################################################################
+#
+# Plotting class
+# ==============
+#
+# This class uses multiprocessing to spawn a process to run code from the
+# class above. When initialized, it creates a pipe and an instance of
+# ``ProcessPlotter`` which will be run in a separate process.
+#
+# When run from the command line, the parent process sends data to the spawned
+# process which is then plotted via the callback function specified in
+# ``ProcessPlotter:__call__``.
+#
+
 
 class NBPlot(object):
     def __init__(self):
         self.plot_pipe, plotter_pipe = Pipe()
         self.plotter = ProcessPlotter()
-        self.plot_process = Process(target=self.plotter,
-                                    args=(plotter_pipe,))
+        self.plot_process = Process(
+            target=self.plotter,
+            args=(plotter_pipe,)
+        )
         self.plot_process.daemon = True
         self.plot_process.start()
 
@@ -84,8 +112,8 @@ def main():
     for ii in range(10):
         pl.plot()
         time.sleep(0.5)
-    input('press Enter...')
     pl.plot(finished=True)
 
+
 if __name__ == '__main__':
     main()
