Fix pydata#2127

spencerkclark · May 14, 2018 · 8ff7c36 · 8ff7c36
1 parent ebe0dd0
commit 8ff7c36
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/xarray/coding/times.py b/xarray/coding/times.py
@@ -253,7 +253,12 @@ def infer_datetime_units(dates):
     else:
         reference_date = dates[0] if len(dates) > 0 else '1970-01-01'
         reference_date = format_cftime_datetime(reference_date)
-    unique_timedeltas = np.unique(np.diff(dates)).astype('timedelta64[ns]')
+    unique_timedeltas = np.unique(np.diff(dates))
+    if unique_timedeltas.dtype == np.dtype('O'):
+        # Convert to np.timedelta64 objects one at a time to work around a
+        # NumPy casting bug (GH 2127)
+        unique_timedeltas = np.array([np.timedelta64(delta, 'ns')
+                                      for delta in unique_timedeltas])
     units = _infer_time_units_from_diff(unique_timedeltas)
     return '%s since %s' % (units, reference_date)
 

diff --git a/xarray/tests/test_coding_times.py b/xarray/tests/test_coding_times.py
@@ -587,6 +587,9 @@ def test_infer_cftime_datetime_units():
                  'seconds since 1900-01-01 00:00:00.000000'),
                 ([date_type(1900, 1, 1),
                   date_type(1900, 1, 2, 0, 0, 0, 5)],
+                 'days since 1900-01-01 00:00:00.000000'),
+                ([date_type(1900, 1, 1), date_type(1900, 1, 8),
+                  date_type(1900, 1, 16)],
                  'days since 1900-01-01 00:00:00.000000')]:
             assert expected == coding.times.infer_datetime_units(dates)