matplotlib · NelleV · Jul 15, 2017 · Jul 3, 2017 · Jul 3, 2017 · Jul 3, 2017
diff --git a/doc/api/api_changes/2017-07-03-DS-logscale_masked.rst b/doc/api/api_changes/2017-07-03-DS-logscale_masked.rst
@@ -0,0 +1,8 @@
+Default behavior of log scales changed to mask <= 0 values
+``````````````````````````````````````````````````````````
+
+Calling `matplotlib.axes.Axes.set_xscale` or `matplotlib.axes.Axes.set_yscale`
+now uses 'mask' as the default method to handle invalid values (as opposed to
+'clip'). This means that any values <= 0 on a log scale will not be shown.
+
+Previously they were clipped to a very small number and shown.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -1578,7 +1578,6 @@ def semilogx(self, *args, **kwargs):
             self.cla()
         d = {'basex': kwargs.pop('basex', 10),
              'subsx': kwargs.pop('subsx', None),
-             'nonposx': kwargs.pop('nonposx', 'mask'),
              }
 
         self.set_xscale('log', **d)
@@ -1629,7 +1628,6 @@ def semilogy(self, *args, **kwargs):
             self.cla()
         d = {'basey': kwargs.pop('basey', 10),
              'subsy': kwargs.pop('subsy', None),
-             'nonposy': kwargs.pop('nonposy', 'mask'),
              }
         self.set_yscale('log', **d)
         b = self._hold
@@ -2753,6 +2751,10 @@ def errorbar(self, x, y, yerr=None, xerr=None,
 
             %(Line2D)s
 
+        Notes
+        -----
+        Error bars with negative values will not be shown when plotted on a
+        logarithmic axis.
         """
         kwargs = cbook.normalize_kwargs(kwargs, _alias_map)
         # anything that comes in as 'None', drop so the default thing

diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -2961,10 +2961,10 @@ def set_xscale(self, value, **kwargs):
 
         matplotlib.scale.LogisticTransform : logit transform
         """
-        # If the scale is being set to log, clip nonposx to prevent headaches
+        # If the scale is being set to log, mask nonposx to prevent headaches
         # around zero
         if value.lower() == 'log' and 'nonposx' not in kwargs:
-            kwargs['nonposx'] = 'clip'
+            kwargs['nonposx'] = 'mask'
 
         g = self.get_shared_x_axes()
         for ax in g.get_siblings(self):
@@ -3255,10 +3255,10 @@ def set_yscale(self, value, **kwargs):
 
         matplotlib.scale.LogisticTransform : logit transform
         """
-        # If the scale is being set to log, clip nonposy to prevent headaches
+        # If the scale is being set to log, mask nonposy to prevent headaches
         # around zero
         if value.lower() == 'log' and 'nonposy' not in kwargs:
-            kwargs['nonposy'] = 'clip'
+            kwargs['nonposy'] = 'mask'
 
         g = self.get_shared_y_axes()
         for ax in g.get_siblings(self):

diff --git a/lib/matplotlib/tests/baseline_images/test_axes/log_scales.png b/lib/matplotlib/tests/baseline_images/test_axes/log_scales.png