BUG: mask NaNs in non-ts plots

Author: Chang She

pandas/tools/plotting.py

@@ -615,6 +615,10 @@ def _make_plot(self):
                 if self.style:
                     style = self.style
 
+                mask = com.isnull(y)
+                if mask.any():
+                    y = np.ma.array(y)
+                    y = np.ma.masked_where(mask, y)
                 plotf(ax, x, y, style, label=label, **self.kwds)
                 ax.grid(self.grid)
                 idx = getattr(self.data, 'index', None)

pandas/tseries/tests/test_plotting.py

@@ -207,6 +207,34 @@ def test_gaps(self):
         mask = data.mask
         self.assert_(mask[5:25, 1].all())
 
+        # irregular
+        plt.close('all')
+        ts = tm.makeTimeSeries()
+        ts = ts[[0, 1, 2, 5, 7, 9, 12, 15, 20]]
+        ts[2:5] = np.nan
+        ax = ts.plot()
+        lines = ax.get_lines()
+        self.assert_(len(lines) == 1)
+        l = lines[0]
+        data = l.get_xydata()
+        self.assert_(isinstance(data, np.ma.core.MaskedArray))
+        mask = data.mask
+        self.assert_(mask[2:5, 1].all())
+
+        # non-ts
+        plt.close('all')
+        idx = [0, 1, 2, 5, 7, 9, 12, 15, 20]
+        ser = Series(np.random.randn(len(idx)), idx)
+        ser[2:5] = np.nan
+        ax = ser.plot()
+        lines = ax.get_lines()
+        self.assert_(len(lines) == 1)
+        l = lines[0]
+        data = l.get_xydata()
+        self.assert_(isinstance(data, np.ma.core.MaskedArray))
+        mask = data.mask
+        self.assert_(mask[2:5, 1].all())
+
     @slow
     def test_secondary_y(self):
         import matplotlib.pyplot as plt