update bands for IO with n_bands

Author: TomDonoghue

specparam/bands/bands.py

@@ -175,14 +175,17 @@ def check_bands(bands):
     ----------
     bands : Bands or dict or int, optional
         How to organize peaks into bands.
+        If None, initializes and empty Bands object.
 
     Returns
     -------
     bands : Bands
         Bands definition.
     """
 
-    if not isinstance(bands, Bands):
+    if bands is None:
+        bands = Bands()
+    elif not isinstance(bands, Bands):
         if isinstance(bands, (dict, OrderedDict)):
             bands = Bands(bands)
         elif isinstance(bands, int):

specparam/io/models.py

@@ -62,7 +62,8 @@ def save_model(model, file_name, file_path=None, append=False,
     mode_labels = ['aperiodic_mode', 'periodic_mode']
 
     # Add bands information to saveable information
-    obj_dict['bands'] = dict(model.results.bands.bands)
+    obj_dict['bands'] = dict(model.results.bands.bands) \
+        if not model.results.bands._n_bands else model.results.bands._n_bands
     bands_label = ['bands'] if model.results.bands else []
 
     # Convert metrics results to saveable information

specparam/objs/results.py

@@ -5,7 +5,7 @@
 
 import numpy as np
 
-from specparam.bands import Bands
+from specparam.bands.bands import check_bands
 from specparam.objs.metrics import Metrics
 from specparam.measures.metrics import METRICS
 from specparam.utils.array import unlog
@@ -103,10 +103,7 @@ def add_bands(self, bands):
             If None, sets bands as an empty Bands object.
         """
 
-        if isinstance(bands, dict):
-            bands = Bands(bands)
-
-        self.bands = deepcopy(bands) if bands else Bands()
+        self.bands = deepcopy(check_bands(bands))
 
 
     def add_metrics(self, metrics):