Adds handling of a model-id-attr to wxcode-modal

improver/cli/wxcode_modal.py

@@ -36,7 +36,7 @@
 
 @cli.clizefy
 @cli.with_output
-def process(*cubes: cli.inputcube):
+def process(*cubes: cli.inputcube, model_id_attr: str = None):
     """Generates a modal weather symbol for the period covered by the input
     weather symbol cubes. Where there are different weather codes available
     for night and day, the modal code returned is always a day code, regardless
@@ -46,6 +46,10 @@ def process(*cubes: cli.inputcube):
         cubes (iris.cube.CubeList):
             A cubelist containing weather symbols cubes that cover the period
             over which a modal symbol is desired.
+        model_id_attr (str):
+            Name of attribute recording source models that should be
+            inherited by the output cube. The source models are expected as
+            a space-separated string.
 
     Returns:
         iris.cube.Cube:
@@ -56,4 +60,4 @@ def process(*cubes: cli.inputcube):
     if not cubes:
         raise RuntimeError("Not enough input arguments. See help for more information.")
 
-    return ModalWeatherCode()(cubes)
+    return ModalWeatherCode(model_id_attr=model_id_attr)(cubes)

improver/wxcode/modal_code.py

@@ -73,10 +73,20 @@ class ModalWeatherCode(BasePlugin):
     covered by the input files.
     """
 
-    def __init__(self):
-        """Create an aggregator instance for reuse"""
+    def __init__(self, model_id_attr: str = None):
+        """
+        Set up plugin and create an aggregator instance for reuse
+
+        Args:
+            model_id_attr:
+                Name of attribute recording source models that should be
+                inherited by the output cube. The source models are expected as
+                a space-separated string.
+        """
         self.aggregator_instance = Aggregator("mode", self.mode_aggregator)
 
+        self.model_id_attr = model_id_attr
+
         # Create the expected cell method for use with single cube inputs
         # that do not pass through the aggregator.
         self.mode_cell_method = iris.coords.CellMethod("mode", coords="time")
@@ -205,6 +215,16 @@ def process(self, cubes: CubeList) -> Cube:
             result = cube.collapsed("time", self.aggregator_instance)
         self._set_blended_times(result)
 
+        if self.model_id_attr:
+            # Update contributing models
+            contributing_models = set()
+            for source_cube in cubes:
+                for model in source_cube.attributes[self.model_id_attr].split(" "):
+                    contributing_models.update([model])
+            result.attributes[self.model_id_attr] = " ".join(
+                sorted(list(contributing_models))
+            )
+
         # Handle any unset points where it was hard to determine a suitable mode
         if (result.data == UNSET_CODE_INDICATOR).any():
             self._group_codes(result, cube)