Return a tuple from `calculate_radii_rossby`

Return a tuple from function `calculate_radii_rossby` instead of a
dictionary.

cost_function.py

@@ -62,7 +62,7 @@ def calculate_radii_rossby(list_eddies, e_overestim, handlers, array_d_init):
     avg_rad /= len(list_eddies)
     
     if n_valid_Rossby != 0: avg_Rossby /= n_valid_Rossby
-    return {"avg_rad": avg_rad, "avg_Rossby": avg_Rossby}
+    return avg_rad, avg_Rossby
 
 def get_SHPC(array_d_ini, date_index):
     i_SHPC = bisect.bisect(array_d_init, date_index) - 1
@@ -159,40 +159,26 @@ for n in g.vertices():
             # to average
 
             # First 7 days calculation
-            first_res = calculate_radii_rossby(segment[:num_of_days_to_avg],
-                                               e_overestim, handlers,
-                                               array_d_init)
-
-            # Average and assign the first radii:
-            g.vp.first_av_rad[n] = first_res['avg_rad']
-
-            # Average and assign the rossbies:
-            g.vp.first_av_ros[n] = first_res['avg_Rossby']
+            g.vp.first_av_rad[n], g.vp.first_av_ros[n] \
+                = calculate_radii_rossby(segment[:num_of_days_to_avg],
+                                         e_overestim, handlers, array_d_init)
 
             # Last 7 days calculation:
-            last_res = calculate_radii_rossby(segment[- num_of_days_to_avg:],
-                                              e_overestim, handlers,
-                                              array_d_init)
-
-            # Average and assign the last radii
-            g.vp.last_av_rad[n] = last_res['avg_rad']
-
-            # Average and assign the rossbies:
-            g.vp.last_av_ros[n] = last_res['avg_Rossby']
+            g.vp.last_av_rad[n], g.vp.last_av_ros[n] \
+                = calculate_radii_rossby(segment[- num_of_days_to_avg:],
+                                         e_overestim, handlers, array_d_init)
         else:
             # The number of eddies in a segment is lower than the number
             # of days over which to average. The values will be the same
             # except for the positions.
-            res = calculate_radii_rossby(segment, e_overestim, handlers,
-                                         array_d_init)
+            avg_rad, avg_Rossby = calculate_radii_rossby(segment, e_overestim,
+                                                         handlers, array_d_init)
 
             # Average and assign the rossbies:
-            avg_Rossby = res['avg_Rossby']
             g.vp.first_av_ros[n] = avg_Rossby
             g.vp.last_av_ros[n] = avg_Rossby
 
             # Average and assign the radii
-            avg_rad = res['avg_rad']
             g.vp.first_av_rad[n] = avg_rad
             g.vp.last_av_rad[n] = avg_rad