Make weights handling simpler by explicitly calling _Weights constructor

lib/iris/analysis/__init__.py

@@ -1288,35 +1288,6 @@ def __init__(self, weights, cube):
         self.array = derived_array
         self.units = derived_units
 
-    @classmethod
-    def get_updated_kwargs(cls, kwargs, cube):
-        """Get kwargs and weights units updated with `weights` information.
-
-        Args:
-
-        * kwargs (dict):
-            Keyword arguments that will be updated if a `weights` keyword is
-            present which is not ``None``.
-        * cube (Cube):
-            Input cube for aggregation. If weights is given as :obj:`str`, try
-            to extract a cell measure with the corresponding name from this
-            cube. Otherwise, this argument is ignored.
-
-        Returns:
-            tuple. A tuple containing the updated keyword arguments and the
-            weights units.
-
-        """
-        kwargs = dict(kwargs)
-        weights_units = None
-
-        if kwargs.get("weights") is not None:
-            weights = cls(kwargs["weights"], cube)
-            kwargs["weights"] = weights.array
-            weights_units = weights.units
-
-        return (kwargs, weights_units)
-
 
 def create_weighted_aggregator_fn(aggregator_fn, axis, **kwargs):
     """Return an aggregator function that can explicitly handle weights.

lib/iris/cube.py

@@ -3836,7 +3836,10 @@ def collapsed(self, coords, aggregator, **kwargs):
         """
         # Update weights kwargs (if necessary) to handle different types of
         # weights
-        (kwargs, weights_units) = _Weights.get_updated_kwargs(kwargs, self)
+        weights_info = None
+        if kwargs.get("weights") is not None:
+            weights_info = _Weights(kwargs["weights"], self)
+            kwargs["weights"] = weights_info.array
 
         # Convert any coordinate names to coordinates
         coords = self._as_list_of_coords(coords)
@@ -3984,7 +3987,7 @@ def collapsed(self, coords, aggregator, **kwargs):
             collapsed_cube,
             coords,
             axis=collapse_axis,
-            _weights_units=weights_units,
+            _weights_units=getattr(weights_info, "units", None),
             **kwargs,
         )
         result = aggregator.post_process(
@@ -4078,7 +4081,10 @@ def aggregated_by(
         """
         # Update weights kwargs (if necessary) to handle different types of
         # weights
-        (kwargs, weights_units) = _Weights.get_updated_kwargs(kwargs, self)
+        weights_info = None
+        if kwargs.get("weights") is not None:
+            weights_info = _Weights(kwargs["weights"], self)
+            kwargs["weights"] = weights_info.array
 
         groupby_coords = []
         dimension_to_groupby = None
@@ -4275,7 +4281,7 @@ def aggregated_by(
             aggregateby_cube,
             groupby_coords,
             aggregate=True,
-            _weights_units=weights_units,
+            _weights_units=getattr(weights_info, "units", None),
             **kwargs,
         )
         # Replace the appropriate coordinates within the aggregate-by cube.
@@ -4415,7 +4421,10 @@ def rolling_window(self, coord, aggregator, window, **kwargs):
         """
         # Update weights kwargs (if necessary) to handle different types of
         # weights
-        (kwargs, weights_units) = _Weights.get_updated_kwargs(kwargs, self)
+        weights_info = None
+        if kwargs.get("weights") is not None:
+            weights_info = _Weights(kwargs["weights"], self)
+            kwargs["weights"] = weights_info.array
 
         coord = self._as_list_of_coords(coord)[0]
 
@@ -4502,7 +4511,7 @@ def rolling_window(self, coord, aggregator, window, **kwargs):
             new_cube,
             [coord],
             action="with a rolling window of length %s over" % window,
-            _weights_units=weights_units,
+            _weights_units=getattr(weights_info, "units", None),
             **kwargs,
         )
         # and perform the data transformation, generating weights first if

lib/iris/tests/test_analysis.py

@@ -1814,35 +1814,13 @@ def test_init_with_cell_measure(self):
         np.testing.assert_array_equal(weights.array, self.data)
         assert weights.units == "m2"
 
-    def test_get_updated_kwargs_no_weights(self):
-        kwargs = {"test": [1, 2, 3]}
-        (new_kwargs, weights_units) = _Weights.get_updated_kwargs(
-            kwargs, self.cube
-        )
-        assert new_kwargs is not kwargs
-        assert new_kwargs == {"test": [1, 2, 3]}
-        assert weights_units is None
-
-    def test_get_updated_kwargs_weights_none(self):
-        kwargs = {"test": [1, 2, 3], "weights": None}
-        (new_kwargs, weights_units) = _Weights.get_updated_kwargs(
-            kwargs, self.cube
-        )
-        assert new_kwargs is not kwargs
-        assert new_kwargs == {"test": [1, 2, 3], "weights": None}
-        assert weights_units is None
-
-    def test_get_updated_kwargs_weights(self):
-        kwargs = {"test": [1, 2, 3], "weights": self.data}
-        (new_kwargs, weights_units) = _Weights.get_updated_kwargs(
-            kwargs, self.cube
-        )
-        assert new_kwargs is not kwargs
-        assert len(new_kwargs) == 2
-        assert new_kwargs["test"] == [1, 2, 3]
-        assert isinstance(new_kwargs["weights"], self.target_type)
-        assert new_kwargs["weights"] is self.data
-        assert weights_units == "1"
+    def test_init_with_list(self):
+        list_in = [0, 1, 2]
+        weights = _Weights(list_in, self.cube)
+        assert isinstance(weights.array, list)
+        assert isinstance(weights.units, cf_units.Unit)
+        assert weights.array is list_in
+        assert weights.units == "1"
 
 
 class TestWeightsLazy(TestWeights):