get closest NSB among those with the same cleaning

src/osa/utils/utils.py

@@ -364,7 +364,7 @@ def get_mc_nsb_dir(run_id: int, rf_models_dir: Path) -> Path:
     closest to that of the data for a given run.
     """
     analysis_dir = options.directory
-    _, additional_nsb, _ = find_tailcuts(analysis_dir, run_id)
+    additional_nsb = get_nsb_level(analysis_dir, run_id)
 
     rf_models_prefix = cfg.get("lstchain", "mc_prod")
     nsb_dict = get_nsb_dict(rf_models_dir, rf_models_prefix)
@@ -373,6 +373,20 @@ def get_mc_nsb_dir(run_id: int, rf_models_dir: Path) -> Path:
     return nsb_dict[closest_nsb_value]
 
 
+def get_nsb_level(analysis_dir, run_id):
+    """Choose the closest NSB among those that are processed with the same cleaning level."""
+    analysis_dir = options.directory
+    _, nsb, config = find_tailcuts(analysis_dir, run_id)
+    picture_th = config["picture_thresh"]
+
+    nsb_levels = np.array([0.00, 0.07, 0.14, 0.22, 0.38, 0.50, 0.81, 1.25, 1.76, 2.34])
+    pth = np.array([8, 8, 8, 8, 10, 10, 12, 14, 16, 18])
+    candidate_nsbs = nsb_levels[pth==picture_th]
+
+    diff = abs(candidate_nsbs - nsb)
+    return candidate_nsbs[np.argsort(diff)][0]
+
+
 def get_RF_model(run_id: int) -> Path:
     """Get the path of the RF models to be used in the DL2 production for a given run.