Handle xunits for bins in axes.hist

Author: alexrudy

lib/matplotlib/axes/_axes.py

@@ -6575,6 +6575,9 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
         if bin_range is not None:
             bin_range = self.convert_xunits(bin_range)
 
+        if not cbook.is_scalar_or_string(bins):
+            bins = self.convert_xunits(bins)
+
         # We need to do to 'weights' what was done to 'x'
         if weights is not None:
             w = cbook._reshape_2D(weights, 'weights')

lib/matplotlib/tests/test_axes.py

@@ -1752,6 +1752,20 @@ def test_hist_datetime_datasets():
     ax.hist(data, stacked=True)
     ax.hist(data, stacked=False)
 
+@pytest.mark.parametrize("bins_preprocess", [lambda bins: None, mpl.dates.date2num, lambda bins: bins], 
+                         ids=['None', 'date2num', 'datetime.datetime'])
+def test_hist_datetime_datasets_bins(bins_preprocess):
+    data = [[datetime.datetime(2019, 1, 5), datetime.datetime(2019, 1, 11), 
+             datetime.datetime(2019, 2, 1), datetime.datetime(2019, 3, 1)],
+            [datetime.datetime(2019, 1, 11), datetime.datetime(2019, 2, 5), 
+             datetime.datetime(2019, 2, 18), datetime.datetime(2019, 3, 1)]]
+
+    date_edges = [datetime.datetime(2019, 1, 1), datetime.datetime(2019, 2, 1), 
+                  datetime.datetime(2019, 3, 1),] 
+    
+    fig, ax = plt.subplots()
+    ax.hist(data, bins=bins_preprocess(date_edges), stacked=True)
+    ax.hist(data, bins=bins_preprocess(date_edges), stacked=False)
 
 @pytest.mark.parametrize('data, expected_number_of_hists',
                          [([], 1),