Fixing bugs when no feasible solution found

PatrickOHara · Aug 14, 2023 · 6e70364 · 6e70364
1 parent e9986a7
commit 6e70364
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Showing 2 changed files with 27 additions and 11 deletions.
diff --git a/pctsp/apps/tables_app.py b/pctsp/apps/tables_app.py
@@ -235,8 +235,10 @@ def cost_cover_table(
     ccdf: pd.DataFrame = pd.read_csv(filename)
     ccdf = ccdf.loc[ccdf["cost_function"] != EdgeWeightType.SEMI_MST]
     # create new columns
-    ccdf["gap"] = (ccdf["upper_bound"] - ccdf["lower_bound"]) / ccdf["lower_bound"]
-    ccdf["optimal"] = ccdf["gap"] == 0
+    SCIP_STATUS_OPTIMAL = 11        # see https://www.scipopt.org/doc/html/type__stat_8h_source.php
+    SCIP_STATUS_INFEASIBLE = 12
+    ccdf["gap"] = ccdf.apply(lambda x: np.nan if x["status"] == SCIP_STATUS_INFEASIBLE else (x["upper_bound"] - x["lower_bound"]) / x["lower_bound"], axis="columns")
+    ccdf["optimal"] = (ccdf["gap"] == 0) & (ccdf["status"] == SCIP_STATUS_OPTIMAL)
 
     def get_cc_name(cc_disjoint_paths: bool, cc_shortest_paths: bool) -> str:
         if cc_disjoint_paths and not cc_shortest_paths:
@@ -286,14 +288,17 @@ def get_cc_name(cc_disjoint_paths: bool, cc_shortest_paths: bool) -> str:
     df = df.drop(
         [
             "avg_cuts",
-            "num_feasible_solutions",
             "num_cost_cover_disjoint_paths",
             "num_cost_cover_shortest_paths",
             "nconss_presolve_disjoint_paths",
             "nconss_presolve_shortest_paths",
         ],
         axis="columns",
     )
+    if experiment_name == ExperimentName.cc_londonaq_alpha:
+        df = df.drop("num_optimal_solutions", axis="columns")
+    elif experiment_name == ExperimentName.cost_cover:
+        df = df.drop("num_feasible_solutions", axis="columns")
     df = df.unstack()
     df = df.swaplevel(0, 1, axis="columns").sort_index(axis=1)
     df = pretty_dataframe(df)

diff --git a/src/algorithms.cpp b/src/algorithms.cpp
@@ -37,9 +37,12 @@ std::vector<std::pair<PCTSPvertex, PCTSPvertex>> solvePrizeCollectingTSP(
 ) {
     auto edge_var_map = modelPrizeCollectingTSP(scip, graph, heuristic_edges, cost_map, prize_map, quota, root_vertex, name);
     SCIPsolve(scip);
-    SCIP_SOL* sol = SCIPgetBestSol(scip);
-    auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
-    return getVertexPairVectorFromEdgeSubset(graph, solution_edges);
+    if (SCIPgetStatus(scip) != SCIP_INFEASIBLE) {
+        SCIP_SOL* sol = SCIPgetBestSol(scip);
+        auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
+        return getVertexPairVectorFromEdgeSubset(graph, solution_edges);
+    }
+    return std::vector<std::pair<PCTSPvertex, PCTSPvertex>>();
 }
 
 std::vector<std::pair<PCTSPvertex, PCTSPvertex>> solvePrizeCollectingTSP(
@@ -55,9 +58,13 @@ std::vector<std::pair<PCTSPvertex, PCTSPvertex>> solvePrizeCollectingTSP(
 ) {
     auto edge_var_map = modelPrizeCollectingTSP(scip, graph, edge_list, heuristic_edges, cost_dict, prize_dict, quota, root_vertex, name);
     SCIPsolve(scip);
-    SCIP_SOL* sol = SCIPgetBestSol(scip);
-    auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
-    return getVertexPairVectorFromEdgeSubset(graph, solution_edges);
+    if (SCIPgetStatus(scip) != SCIP_INFEASIBLE) {
+        SCIP_SOL* sol = SCIPgetBestSol(scip);
+        auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
+        return getVertexPairVectorFromEdgeSubset(graph, solution_edges);
+    }
+    BOOST_LOG_TRIVIAL(info) << "Solution is not feasible. Returning empty solution vector.";
+    return std::vector<std::pair<PCTSPvertex, PCTSPvertex>>();
 }
 
 SummaryStats getSummaryStatsFromSCIP(SCIP* scip) {
@@ -198,10 +205,14 @@ std::vector<std::pair<PCTSPvertex, PCTSPvertex>> solvePrizeCollectingTSP(
 
     // solve the model
     SCIPsolve(scip);
+    BOOST_LOG_TRIVIAL(info) << "SCIP solve has finished.";
 
     // get the solution
-    SCIP_SOL* sol = SCIPgetBestSol(scip);
-    auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
+    std::vector<PCTSPedge> solution_edges = std::vector<PCTSPedge>();
+    if (SCIPgetNSols(scip) > 0) {
+        SCIP_SOL* sol = SCIPgetBestSol(scip);
+        auto solution_edges = getSolutionEdges(scip, graph, sol, edge_var_map);
+    }
 
     // get the node stats of the solver
     // auto node_stats = node_eventhdlr->getNodeStatsVector();