potential fix for issue #328

Changelog

@@ -2,6 +2,8 @@ since version 1.6.3 release
 ===========================
  * build musllinux wheels (issue #307).
  * return empty array if one provided to date2num (issue #315).
+ * numpy 2.0 compatibility (issue #325).
+ * handle nan/inf in num2date (issue #328).
 
 version 1.6.3 (release tag v1.6.3rel)
 =====================================

src/cftime/_cftime.pyx

@@ -620,6 +620,9 @@ def num2date(
     factor = UNIT_CONVERSION_FACTORS[unit]
     times = np.asanyarray(times)  # Allow list as input
     times = upcast_times(times)
+    # convert to masked array if any nan or inf values present
+    if not np.isfinite(times).all():
+        times = np.ma.masked_invalid(times)
     scaled_times = scale_times(times, factor)
     scaled_times = cast_to_int(scaled_times,units=unit)
 

test/test_cftime.py

@@ -930,6 +930,19 @@ def roundtrip(delta,eps,units):
         # date2num should return an empty array if given one (issue #315)
         d = cftime.date2num([], 'seconds since 2000-01-01 12:00:00')
         assert d.size==0
+        # issue #328:  handle nan/inf in num2date.
+        times = np.array([1,2,3,np.nan],dtype=np.float64)
+        expected = np.array([DatetimeGregorian(2000, 1, 2, 0, 0, 0, 0),
+                             DatetimeGregorian(2000, 1, 3, 0, 0, 0, 0),
+                             DatetimeGregorian(2000, 1, 4, 0, 0, 0, 0),
+                             DatetimeGregorian(2000, 1, 5, 0, 0, 0, 0)])
+        mask = [False, False, False, True]
+        expected = np.ma.masked_array(expected, mask=mask)
+        result = cftime.num2date(times, 'days since 2000-01-01', 'standard')
+        np.testing.assert_equal(result, expected)
+        times = np.array([1,2,3,np.inf],dtype=np.float64)
+        result = cftime.num2date(times, 'days since 2000-01-01', 'standard')
+        np.testing.assert_equal(result, expected)
 
 
 class TestDate2index(unittest.TestCase):