Merge pull request #14635 from astrofrog/fix-negative-log-limits

timhoffm · web-flow · commit 32a111b591bf · 2019-06-30T11:17:52.000+02:00
Fix bug when setting negative limits and using log scale
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -3249,7 +3249,10 @@ def set_xlim(self, left=None, right=None, emit=True, auto=False,
             if right is None:
                 right = old_right
 
-        if self.get_xscale() == 'log':
+        if self.get_xscale() == 'log' and (left <= 0 or right <= 0):
+            # Axes init calls set_xlim(0, 1) before get_xlim() can be called,
+            # so only grab the limits if we really need them.
+            old_left, old_right = self.get_xlim()
             if left <= 0:
                 cbook._warn_external(
                     'Attempted to set non-positive left xlim on a '
@@ -3629,7 +3632,10 @@ def set_ylim(self, bottom=None, top=None, emit=True, auto=False,
             if top is None:
                 top = old_top
 
-        if self.get_yscale() == 'log':
+        if self.get_yscale() == 'log' and (bottom <= 0 or top <= 0):
+            # Axes init calls set_xlim(0, 1) before get_xlim() can be called,
+            # so only grab the limits if we really need them.
+            old_bottom, old_top = self.get_ylim()
             if bottom <= 0:
                 cbook._warn_external(
                     'Attempted to set non-positive bottom ylim on a '
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -2141,6 +2141,17 @@ def test_log_scales():
     ax.set_xscale('log', basex=9.0)
 
 
+def test_log_scales_invalid():
+    fig = plt.figure()
+    ax = fig.add_subplot(1, 1, 1)
+    ax.set_xscale('log')
+    with pytest.warns(UserWarning, match='Attempted to set non-positive'):
+        ax.set_xlim(-1, 10)
+    ax.set_yscale('log')
+    with pytest.warns(UserWarning, match='Attempted to set non-positive'):
+        ax.set_ylim(-1, 10)
+
+
 @image_comparison(['stackplot_test_image', 'stackplot_test_image'])
 def test_stackplot():
     fig = plt.figure()
