Add helper function for layout creation in VF2Layout scoring loop

Qiskit · Nov 18, 2022 · 50aab71 · 50aab71
1 parent 7c38723
commit 50aab71
Showing 1 changed file with 10 additions and 15 deletions.
diff --git a/qiskit/transpiler/passes/layout/vf2_layout.py b/qiskit/transpiler/passes/layout/vf2_layout.py
@@ -168,25 +168,26 @@ def run(self, dag):
             os.getenv("QISKIT_IN_PARALLEL", "FALSE").upper() != "TRUE"
             or os.getenv("QISKIT_FORCE_THREADS", "FALSE").upper() == "TRUE"
         )
+
+        def mapping_to_layout(layout_mapping):
+            return Layout({reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()})
+
         for mapping in mappings:
             trials += 1
             logger.debug("Running trial: %s", trials)
             stop_reason = VF2LayoutStopReason.SOLUTION_FOUND
             layout_mapping = {im_i: cm_nodes[cm_i] for cm_i, im_i in mapping.items()}
+
             # If the graphs have the same number of nodes we don't need to score or do multiple
             # trials as the score heuristic currently doesn't weigh nodes based on gates on a
             # qubit so the scores will always all be the same
             if len(cm_graph) == len(im_graph):
-                chosen_layout = Layout(
-                    {reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()}
-                )
+                chosen_layout = mapping_to_layout(layout_mapping)
                 break
             # If there is no error map avilable we can just skip the scoring stage as there
             # is nothing to score with, so any match is the best we can find.
             if self.avg_error_map is None:
-                chosen_layout = Layout(
-                    {reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()}
-                )
+                chosen_layout = mapping_to_layout(layout_mapping)
                 break
             layout_score = vf2_utils.score_layout(
                 self.avg_error_map,
@@ -201,20 +202,14 @@ def run(self, dag):
             # waste time finding additional mappings that will at best match
             # the performance, so exit early in this case
             if layout_score == 0.0:
-                chosen_layout = Layout(
-                    {reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()}
-                )
+                chosen_layout = mapping_to_layout(layout_mapping)
                 break
             logger.debug("Trial %s has score %s", trials, layout_score)
             if chosen_layout is None:
-                chosen_layout = Layout(
-                    {reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()}
-                )
+                chosen_layout = mapping_to_layout(layout_mapping)
                 chosen_layout_score = layout_score
             elif layout_score < chosen_layout_score:
-                layout = Layout(
-                    {reverse_im_graph_node_map[k]: v for k, v in layout_mapping.items()}
-                )
+                layout = mapping_to_layout(layout_mapping)
                 logger.debug(
                     "Found layout %s has a lower score (%s) than previous best %s (%s)",
                     layout,