added fix for phaseplots to handle no arrow case correctly

murrayrm · murrayrm · commit 0104e4bd036a · 2016-06-13T10:09:11.000-07:00
diff --git a/control/phaseplot.py b/control/phaseplot.py
@@ -120,7 +120,10 @@ def phase_plot(odefun, X=None, Y=None, scale=1, X0=None, T=None,
     # Figure out ranges for phase plot (argument processing)
     #
     #! TODO: need to add error checking to arguments
+    #! TODO: think through proper action if multiple options are given
+    #
     autoFlag = False; logtimeFlag = False; timeptsFlag = False; Narrows = 0;
+
     if lingrid is not None:
         autoFlag = True;
         Narrows = lingrid;
@@ -138,14 +141,18 @@ def phase_plot(odefun, X=None, Y=None, scale=1, X0=None, T=None,
         timeptsFlag = True;
         Narrows = len(timepts);
 
-    else:
-        # Figure out the set of points for the quiver plot
-        #! TODO: Add sanity checks
+    # Figure out the set of points for the quiver plot
+    #! TODO: Add sanity checks
+    elif (X is not None and Y is not None):
         (x1, x2) = np.meshgrid(
             frange(X[0], X[1], float(X[1]-X[0])/X[2]),
             frange(Y[0], Y[1], float(Y[1]-Y[0])/Y[2]));
+    else:
+        # If we weren't given any grid points, don't plot arrows
+        Narrows = 0;
 
-    if ((not autoFlag) and (not logtimeFlag) and (not timeptsFlag)):
+    if ((not autoFlag) and (not logtimeFlag) and (not timeptsFlag)
+        and (Narrows > 0)):
         # Now calculate the vector field at those points
         (nr,nc) = x1.shape;
         dx = np.empty((nr, nc, 2))
diff --git a/control/tests/phaseplot_test.py b/control/tests/phaseplot_test.py
@@ -13,7 +13,7 @@
 import numpy as np
 import scipy as sp
 import matplotlib.pyplot as mpl
-from control.phaseplot import *
+from control import phase_plot
 from numpy import pi
 
 class TestPhasePlot(unittest.TestCase):
@@ -53,6 +53,19 @@ def testOscillatorParams(self):
                    [-0.5,-1], [-0.7,-1], [-1,-1], [-1.3,-1]],
                   T = np.linspace(0, 10, 100), parms = (m, b, k));
 
+    def testNoArrows(self):
+        # Test case from aramakrl that was generating a type error
+        # System does not have arrows
+        def d1(x1x2,t):
+            x1,x2 = x1x2
+            return np.array([x2, x2 - 2*x1])
+
+        x1x2_0 = np.array([[-1.,1.], [-1.,-1.], [1.,1.], [1.,-1.],
+                           [-1.,0.],[1.,0.],[0.,-1.],[0.,1.],[0.,0.]])
+
+        mpl.figure(1)
+        phase_plot(d1,X0=x1x2_0,T=100)
+
     # Sample dynamical systems - inverted pendulum
     def invpend_ode(self, x, t, m=1., l=1., b=0, g=9.8):
         import numpy as np
