simplify residual gas logic

gwinc/ifo/noises.py

@@ -904,23 +904,21 @@ def _calc_residual_gas_damping(f, ifo, species, sustf):
 
     Can get rid of if budgets are calculated at runtime
     """
-    squeezed_film = ifo.Infrastructure.ResidualGas.get('SqueezedFilm', None)
+    squeezed_film = ifo.Infrastructure.ResidualGas.get('SqueezedFilm', Struct())
+
+    if squeezed_film is None:
+        raise ValueError('Must specify either excess damping or a gap')
 
     # Calculate squeezed film for ETM and ITM seperately if either is given
     # explicitly. If only one is given, it is not computed for the other one.
-    if squeezed_film:
-        if ('ETM' in squeezed_film) or ('ITM' in squeezed_film):
-            n = np.zeros_like(f)
-            if 'ETM' in squeezed_film:
-                n_ETM = noise.residualgas.residual_gas_damping(
-                    f, ifo, species, sustf, squeezed_film.ETM)
-                n += 2 * n_ETM
-
-            if 'ITM' in squeezed_film:
-                n_ITM = noise.residualgas.residual_gas_damping(
-                    f, ifo, species, sustf, squeezed_film.ITM)
-
-                n += 2 * n_ITM
+    if ('ETM' in squeezed_film) or ('ITM' in squeezed_film):
+        squeezed_film_ETM = squeezed_film.get('ETM', Struct())
+        squeezed_film_ITM = squeezed_film.get('ITM', Struct())
+        n_ETM = noise.residualgas.residual_gas_damping(
+            f, ifo, species, sustf, squeezed_film_ETM)
+        n_ITM = noise.residualgas.residual_gas_damping(
+            f, ifo, species, sustf, squeezed_film_ITM)
+        n = 2 * (n_ETM + n_ITM)
 
     # Otherwise the same calculation is used for both.
     else:

gwinc/noise/residualgas.py

@@ -96,7 +96,7 @@ def residual_gas_damping(f, ifo, species, sustf, squeezed_film):
 
     # add squeezed film damping if necessary as parametrized by
     # Eq (5) of http://dx.doi.org/10.1103/PhysRevD.84.063007
-    if squeezed_film:
+    if squeezed_film.keys():
         # the excess force noise and diffusion time are specified directly
         if 'ExcessDamping' in squeezed_film:
             # ExcessDamping is the ratio of the total gas damping noise at DC