trainScript: --run_id -> --run-id; remove --exp_id

--exp_id was never used, due to how MLflow searches through its runs.

src/gz21_ocean_momentum/trainScript.py

@@ -99,16 +99,11 @@ def check_str_is_None(string_in: str):
 description = (
     "Trains a model on a chosen dataset from the store."
     "Allows to set training parameters via the CLI."
+    "Use one of either --run-id or --forcing-data-path."
 )
 parser = argparse.ArgumentParser(description=description)
 
-# access input forcing data via MLflow
-parser.add_argument(
-    "--exp_id",
-    type=int,
-    help="Experiment id of the source dataset containing the " "training data.",
-)
-parser.add_argument("--run_id", type=str, help="Run id of the source dataset")
+parser.add_argument("--run-id", type=str, help="MLflow run ID of data step containing forcing data to use")
 
 # access input forcing data via absolute filepath
 parser.add_argument("--forcing-data-path", type=str, help="Filepath of the forcing data")
@@ -175,22 +170,20 @@ def try_get_forcing_data_filepath(params):
 
     Returns a filepath which should be a zarr dataset. Correctness is not
     asserted, so the filepath may not exist or may not be a valid zarr dataset.
-
-    TODO bit wonky the way we do mutual exclusion.
     """
-    if params.run_id is not None and params.exp_id is not None:
+    if params.run_id is not None:
         if params.forcing_data_path is not None:
+            # got both --run-id and --forcing-data-path: bad
             raise argparse.ArgumentError("overlapping options provided (--forcing-data-path and --exp-id)")
 
-        # got run_id and exp_id: try to use
-        # TODO we don't actually use exp_id
-        mlflow.log_param("source.exp_id", params.exp_id)
-        mlflow.log_param("source.run_id", params.run_id)
+        # got only --run-id: obtain path via MLflow
+        mlflow.log_param("source.run-id", params.run_id)
 
         mlflow_client = mlflow.tracking.MlflowClient()
         return mlflow_client.download_artifacts(params.run_id, "forcing")
 
     if params.forcing_data_path is not None:
+        # got only --forcing-data-path: use
         return params.forcing_data_path
 
     # if we get here, neither options were provided