Fix minor bugs in data_config.yaml workflow (#40)

### Summary
#31 introduced three minor bugs
that are fixed with this PR:

- r"" strings are not required in units of `data_config.yaml`
- dictionaries cannot be passed as argsparse, rather JSON strings. This
bug is related to the flag `var_leads_metrics_watch`

---------

Co-authored-by: joeloskarsson <[email protected]>

neural_lam/data_config.yaml

@@ -21,8 +21,8 @@ dataset:
   var_units:
     - Pa
     - Pa
-    - r"$\mathrm{W}/\mathrm{m}^2$"
-    - r"$\mathrm{W}/\mathrm{m}^2$"
+    - $\mathrm{W}/\mathrm{m}^2$
+    - $\mathrm{W}/\mathrm{m}^2$
     - ""
     - ""
     - K
@@ -33,9 +33,9 @@ dataset:
     - m/s
     - m/s
     - m/s
-    - r"$\mathrm{kg}/\mathrm{m}^2$"
-    - r"$\mathrm{m}^2/\mathrm{s}^2$"
-    - r"$\mathrm{m}^2/\mathrm{s}^2$"
+    - $\mathrm{kg}/\mathrm{m}^2$
+    - $\mathrm{m}^2/\mathrm{s}^2$
+    - $\mathrm{m}^2/\mathrm{s}^2$
   var_longnames:
     - pres_heightAboveGround_0_instant
     - pres_heightAboveSea_0_instant

neural_lam/models/ar_model.py

@@ -473,7 +473,7 @@ def create_metric_log_dict(self, metric_tensor, prefix, metric_name):
         # Check if metrics are watched, log exact values for specific vars
         if full_log_name in self.args.metrics_watch:
             for var_i, timesteps in self.args.var_leads_metrics_watch.items():
-                var = self.config_loader.dataset.var_nums[var_i]
+                var = self.config_loader.dataset.var_names[var_i]
                 log_dict.update(
                     {
                         f"{full_log_name}_{var}_step_{step}": metric_tensor[

train_model.py

@@ -1,4 +1,5 @@
 # Standard library
+import json
 import random
 import time
 from argparse import ArgumentParser
@@ -196,17 +197,21 @@ def main():
     )
     parser.add_argument(
         "--metrics_watch",
-        type=list,
+        nargs="+",
         default=[],
         help="List of metrics to watch, including any prefix (e.g. val_rmse)",
     )
     parser.add_argument(
         "--var_leads_metrics_watch",
-        type=dict,
-        default={},
-        help="Dict with variables and lead times to log watched metrics for",
+        type=str,
+        default="{}",
+        help="""JSON string with variable-IDs and lead times to log watched
+             metrics (e.g. '{"1": [1, 2], "3": [3, 4]}')""",
     )
     args = parser.parse_args()
+    args.var_leads_metrics_watch = {
+        int(k): v for k, v in json.loads(args.var_leads_metrics_watch).items()
+    }
 
     config_loader = config.Config.from_file(args.data_config)