Fix: make examples/tfvis.py Python 3 compatible.

roryyorke · roryyorke · commit 416d1fbbc84e · 2019-01-02T07:51:30.000+02:00
Uses Python 3 tkinter module name; the future package lets this work
in Python 2 as well.
diff --git a/.travis.yml b/.travis.yml
@@ -79,7 +79,8 @@ script:
   - if [[ "$SLYCOT" != "" ]]; then
       export PYTHONPATH=$PWD
       # pmw needed for examples/tfvis.py
-      conda install -c conda-forge pmw
+      # future is needed for Python 2, also for examples/tfvis.py
+      conda install -c conda-forge pmw future
       '(cd examples && bash run_examples.sh)'
     fi
 
diff --git a/examples/tfvis.py b/examples/tfvis.py
@@ -1,4 +1,7 @@
 #!/usr/bin/python
+# needs pmw (in pypi, conda-forge)
+# For Python 2, needs future (in conda pypi and "default")
+
 from __future__ import print_function
 
 """ Simple GUI application for visualizing how the poles/zeros of the transfer
@@ -40,7 +43,7 @@
 """
 
 import control.matlab
-import Tkinter
+import tkinter
 import sys
 import Pmw
 import matplotlib.pyplot as plt
@@ -103,7 +106,7 @@ def __init__(self, parent):
             pass
 
         widgets = (self.numerator_widget, self.denominator_widget)
-        for i in xrange(len(widgets)):
+        for i in range(len(widgets)):
             widgets[i].grid(row=i+1, column=0, padx=20, pady=3)
         Pmw.alignlabels(widgets)
 
@@ -158,24 +161,24 @@ def __init__(self, parent):
         self.zeros = []
         self.poles = []
 
-        self.topframe = Tkinter.Frame(self.master)
+        self.topframe = tkinter.Frame(self.master)
         self.topframe.pack(expand=True, fill='both')
 
-        self.entries = Tkinter.Frame(self.topframe)
+        self.entries = tkinter.Frame(self.topframe)
         self.entries.pack(expand=True, fill='both')
 
-        self.figure = Tkinter.Frame(self.topframe)
+        self.figure = tkinter.Frame(self.topframe)
         self.figure.pack(expand=True, fill='both')
 
-        header = Tkinter.Label(self.entries,
+        header = tkinter.Label(self.entries,
             text='Define the transfer function:')
         header.grid(row=0, column=0, padx=20, pady=7)
 
 
         self.tfi = TFInput(self.entries)
         self.sys = self.tfi.get_tf()
 
-        Tkinter.Button(self.entries, text='Apply', command=self.apply,
+        tkinter.Button(self.entries, text='Apply', command=self.apply,
                width=9).grid(row=0, column=1, rowspan=3, padx=10, pady=5)
 
         self.f_bode = plt.figure(figsize=(4, 4))
@@ -185,25 +188,25 @@ def __init__(self, parent):
 
         self.canvas_pzmap = FigureCanvasTkAgg(self.f_pzmap,
                                                 master=self.figure)
-        self.canvas_pzmap.show()
+        self.canvas_pzmap.draw()
         self.canvas_pzmap.get_tk_widget().grid(row=0, column=0,
                                                 padx=0, pady=0)
 
         self.canvas_bode = FigureCanvasTkAgg(self.f_bode,
                                                 master=self.figure)
-        self.canvas_bode.show()
+        self.canvas_bode.draw()
         self.canvas_bode.get_tk_widget().grid(row=0, column=1,
                                                 padx=0, pady=0)
 
         self.canvas_step = FigureCanvasTkAgg(self.f_step,
                                                 master=self.figure)
-        self.canvas_step.show()
+        self.canvas_step.draw()
         self.canvas_step.get_tk_widget().grid(row=1, column=0,
                                                 padx=0, pady=0)
 
         self.canvas_nyquist = FigureCanvasTkAgg(self.f_nyquist, 
                                                 master=self.figure)
-        self.canvas_nyquist.show()
+        self.canvas_nyquist.draw()
         self.canvas_nyquist.get_tk_widget().grid(row=1, column=1,
                                                     padx=0, pady=0)
 
@@ -302,7 +305,7 @@ def mouse_move(self, event):
                 tfcn = self.tfi.get_tf()
             if (tfcn != None):
                 self.draw_pz(tfcn)
-                self.canvas_pzmap.show()
+                self.canvas_pzmap.draw()
 
     def apply(self):
         """Evaluates the transfer function and produces different plots for
@@ -353,10 +356,10 @@ def redraw(self):
             print("Error plotting step response")
         plt.suptitle('Step Response')
 
-        self.canvas_pzmap.show()
-        self.canvas_bode.show()
-        self.canvas_step.show()
-        self.canvas_nyquist.show()
+        self.canvas_pzmap.draw()
+        self.canvas_bode.draw()
+        self.canvas_step.draw()
+        self.canvas_nyquist.draw()
 
 def create_analysis():
     """ Create main object """
@@ -366,7 +369,7 @@ def handler():
         sys.exit()
 
     # Launch a GUI for the Analysis module
-    root = Tkinter.Tk()
+    root = tkinter.Tk()
     root.protocol("WM_DELETE_WINDOW", handler)
     Pmw.initialise(root)    
     root.title('Analysis of Linear Systems')
