Fix incorrect converter used for horizontal histograms.

anntzer · anntzer · commit 98ebd9d9b349 · 2020-09-20T17:44:04.000+02:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -6464,18 +6464,23 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
         x = cbook._reshape_2D(x, 'x')
         nx = len(x)  # number of datasets
 
-        # Process unit information
-        # Unit conversion is done individually on each dataset
-        self._process_unit_info(
-            {"x" if orientation == "vertical" else "y": x[0]}, kwargs,
-            convert=False)
-        x = [self.convert_xunits(xi) for xi in x]
+        # Process unit information.  _process_unit_info sets the unit and
+        # converts the first dataset; then we convert each following dataset
+        # one at a time.
+        if orientation == "vertical":
+            convert_units = self.convert_yunits
+            x = [*self._process_unit_info({"x": x[0]}, kwargs),
+                 *map(convert_units, x[1:])]
+        else:  # horizontal
+            convert_units = self.convert_yunits
+            x = [*self._process_unit_info({"y": x[0]}, kwargs),
+                 *map(convert_units, x[1:])]
 
         if bin_range is not None:
-            bin_range = self.convert_xunits(bin_range)
+            bin_range = convert_units(bin_range)
 
         if not cbook.is_scalar_or_string(bins):
-            bins = self.convert_xunits(bins)
+            bins = convert_units(bins)
 
         # We need to do to 'weights' what was done to 'x'
         if weights is not None:
