Fix num2date / date2num multidimensional arrays. Remove iterator supp…

…ort. Fix masked arrays (#68)

* Fix num2date / date2num multidimensional arrays. Remove iterator support

cf_units/__init__.py

@@ -703,16 +703,20 @@ def _discard_microsecond(date):
         Date value/s
 
     Returns:
-        datetime, or list of datetime object.
+        datetime, or numpy.ndarray of datetime object.
 
     """
-    is_scalar = False
-    if not hasattr(date, '__iter__'):
-        date = [date]
-        is_scalar = True
-    dates = [d.__class__(d.year, d.month, d.day, d.hour, d.minute, d.second)
-             for d in date]
-    return dates[0] if is_scalar else dates
+    dates = np.asarray(date)
+    shape = dates.shape
+    dates = dates.ravel()
+    # Create date objects of the same type returned by utime.num2date()
+    # (either datetime.datetime or netcdftime.datetime), discarding the
+    # microseconds
+    dates = np.array([d and d.__class__(d.year, d.month, d.day,
+                                        d.hour, d.minute, d.second)
+                      for d in dates])
+    result = dates[0] if shape is () else dates.reshape(shape)
+    return result
 
 
 def num2date(time_value, unit, calendar):
@@ -798,27 +802,25 @@ def _num2date_to_nearest_second(time_value, utime):
     Returns:
         datetime, or numpy.ndarray of datetime object.
     """
-    is_scalar = False
-    if not hasattr(time_value, '__iter__'):
-        time_value = [time_value]
-        is_scalar = True
-    time_values = np.array(list(time_value))
+    time_values = np.asanyarray(time_value)
+    shape = time_values.shape
+    time_values = time_values.ravel()
 
     # We account for the edge case where the time is in seconds and has a
     # half second: utime.num2date() may produce a date that would round
     # down.
     #
-    # Note that this behaviour is different to the num2date function in older
-    # versions of netcdftime that didn't have microsecond precision. In those
-    # versions, a half-second value would be rounded up or down arbitrarily. It
-    # is probably not possible to replicate that behaviour with the current
-    # version (1.4.1), if one wished to do so for the sake of consistency.
+    # Note that this behaviour is different to the num2date function in version
+    # 1.1 and earlier of netcdftime that didn't have microsecond precision. In
+    # those versions, a half-second value would be rounded up or down
+    # arbitrarily. It is probably not possible to replicate that behaviour with
+    # later versions, if one wished to do so for the sake of consistency.
     has_half_seconds = np.logical_and(utime.units == 'seconds',
                                       time_values % 1. == 0.5)
     dates = utime.num2date(time_values)
     try:
         # We can assume all or none of the dates have a microsecond attribute
-        microseconds = np.array([d.microsecond for d in dates])
+        microseconds = np.array([d.microsecond if d else 0 for d in dates])
     except AttributeError:
         microseconds = 0
     round_mask = np.logical_or(has_half_seconds, microseconds != 0)
@@ -827,12 +829,9 @@ def _num2date_to_nearest_second(time_value, utime):
         useconds = Unit('second')
         second_frac = useconds.convert(0.75, utime.units)
         dates[ceil_mask] = utime.num2date(time_values[ceil_mask] + second_frac)
-    # Create date objects of the same type returned by utime.num2date()
-    # (either datetime.datetime or netcdftime.datetime), discarding the
-    # microseconds
     dates[round_mask] = _discard_microsecond(dates[round_mask])
-
-    return dates[0] if is_scalar else dates
+    result = dates[0] if shape is () else dates.reshape(shape)
+    return result
 
 
 ########################################################################

cf_units/tests/integration/test__num2date_to_nearest_second.py

@@ -59,11 +59,20 @@ def test_sequence(self):
         res = _num2date_to_nearest_second(nums, utime)
         np.testing.assert_array_equal(exp, res)
 
-    def test_iter(self):
+    def test_multidim_sequence(self):
         utime = netcdftime.utime('seconds since 1970-01-01',  'gregorian')
-        nums = iter([5., 10.])
-        exp = [datetime.datetime(1970, 1, 1, 0, 0, 5),
-               datetime.datetime(1970, 1, 1, 0, 0, 10)]
+        nums = [[20., 40., 60.],
+                [80, 100., 120.]]
+        exp_shape = (2, 3)
+        res = _num2date_to_nearest_second(nums, utime)
+        self.assertEqual(exp_shape, res.shape)
+
+    def test_masked_ndarray(self):
+        utime = netcdftime.utime('seconds since 1970-01-01',  'gregorian')
+        nums = np.ma.masked_array([20., 40., 60.], [False, True, False])
+        exp = [datetime.datetime(1970, 1, 1, 0, 0, 20),
+               None,
+               datetime.datetime(1970, 1, 1, 0, 1)]
         res = _num2date_to_nearest_second(nums, utime)
         np.testing.assert_array_equal(exp, res)
 

cf_units/tests/integration/test_date2num.py

@@ -52,6 +52,17 @@ def test_sequence(self):
         res = date2num(dates, self.unit, self.calendar)
         np.testing.assert_array_almost_equal(exp, res, decimal=4)
 
+    def test_multidim_sequence(self):
+        dates = [[datetime.datetime(1970, 1, 1, 0, 0, 20),
+                  datetime.datetime(1970, 1, 1, 0, 0, 40),
+                  datetime.datetime(1970, 1, 1, 0, 1)],
+                 [datetime.datetime(1970, 1, 1, 0, 1, 20),
+                  datetime.datetime(1970, 1, 1, 0, 1, 40),
+                  datetime.datetime(1970, 1, 1, 0, 2)]]
+        exp_shape = (2, 3)
+        res = date2num(dates, self.unit, self.calendar)
+        self.assertEqual(exp_shape, res.shape)
+
     def test_discard_mircosecond(self):
         date = datetime.datetime(1970, 1, 1, 0, 0, 5, 750000)
         exp = 5.