use defaultdict

Co-authored-by: Paul Romano <[email protected]>

tests/regression_tests/deplete_with_transport/test.py

@@ -3,6 +3,7 @@
 from math import floor
 import shutil
 from pathlib import Path
+from collections import defaultdict
 
 from difflib import unified_diff
 import numpy as np
@@ -122,18 +123,11 @@ def test_full(run_in_tmpdir, problem, multiproc):
     n_tallies = np.empty(N + 1, dtype=int)
 
     # Get statepoint files for all BOS points and EOL
-    runtimes = {}
+    runtimes = defaultdict(list)
     for n in range(N + 1):
         statepoint = openmc.StatePoint(f"openmc_simulation_n{n}.h5")
-        runtime = statepoint.runtime
-        if n == 0:
-            for measure, time in runtime.items():
-                runtimes.update({measure: np.array([time])})
-        else:
-            for measure, time in runtime.items():
-                current = runtimes[measure]
-                updated = np.append(current, time)
-                runtimes.update({measure: updated})
+        for measure, time in statepoint.runtime.items():
+            runtimes[measure].append(time)
         k_n = statepoint.keff
         k_state[n] = [k_n.nominal_value, k_n.std_dev]
         n_tallies[n] = len(statepoint.tallies)