Support masked dates

oscargus · oscargus · commit 23538842ae44 · 2022-12-15T21:52:05.000+01:00
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -444,7 +444,10 @@ def date2num(d):
     if not iterable:
         d = [d]
 
+    masked = np.ma.is_masked(d)
+    mask = np.ma.getmask(d)
     d = np.asarray(d)
+
     # convert to datetime64 arrays, if not already:
     if not np.issubdtype(d.dtype, np.datetime64):
         # datetime arrays
@@ -458,6 +461,7 @@ def date2num(d):
             d = np.asarray(d)
         d = d.astype('datetime64[us]')
 
+    d = np.ma.masked_array(d, mask=mask) if masked else d
     d = _dt64_to_ordinalf(d)
 
     return d if iterable else d[0]
diff --git a/lib/matplotlib/tests/test_dates.py b/lib/matplotlib/tests/test_dates.py
@@ -69,6 +69,26 @@ def test_date2num_NaT_scalar(units):
     assert np.isnan(tmpl)
 
 
+def test_date2num_masked():
+    # Without tzinfo
+    base = datetime.datetime(2022, 12, 15)
+    dates = np.ma.array([base + datetime.timedelta(days=(2 * i))
+                         for i in range(7)], mask=[0, 1, 1, 0, 0, 0, 1])
+    npdates = mdates.date2num(dates)
+    np.testing.assert_array_equal(np.ma.getmask(npdates),
+                                  (False, True, True, False, False, False,
+                                   True))
+
+    # With tzinfo
+    base = datetime.datetime(2022, 12, 15, tzinfo=mdates.UTC)
+    dates = np.ma.array([base + datetime.timedelta(days=(2 * i))
+                         for i in range(7)], mask=[0, 1, 1, 0, 0, 0, 1])
+    npdates = mdates.date2num(dates)
+    np.testing.assert_array_equal(np.ma.getmask(npdates),
+                                  (False, True, True, False, False, False,
+                                   True))
+
+
 def test_date_empty():
     # make sure we do the right thing when told to plot dates even
     # if no date data has been presented, cf
