Fix bug in axis(): if called with no args or kwargs, don't change autoscale.

Bug reported by Joe Kington.

Author: efiring

lib/matplotlib/axes.py

@@ -1239,11 +1239,17 @@ def apply_aspect(self, position=None):
     def axis(self, *v, **kwargs):
         '''
         Convenience method for manipulating the x and y view limits
-        and the aspect ratio of the plot.
+        and the aspect ratio of the plot. For details, see
+        :func:`~matplotlib.pyplot.axis`.
 
         *kwargs* are passed on to :meth:`set_xlim` and
         :meth:`set_ylim`
         '''
+        if len(v) == 0 and len(kwargs) == 0:
+            xmin, xmax = self.get_xlim()
+            ymin, ymax = self.get_ylim()
+            return xmin, xmax, ymin, ymax
+
         if len(v)==1 and is_string_like(v[0]):
             s = v[0].lower()
             if s=='on': self.set_axis_on()
@@ -1289,7 +1295,6 @@ def axis(self, *v, **kwargs):
         if len(v) != 4:
             raise ValueError('v must contain [xmin xmax ymin ymax]')
 
-
         self.set_xlim([v[0], v[1]])
         self.set_ylim([v[2], v[3]])