Convert MIPSolveStats into dataclass

miplearn/solvers/gurobi.py

@@ -220,16 +220,15 @@ class GurobiSolver(InternalSolver):
                 lb = self.model.objVal
                 ub = self.model.objBound
         ws_value = self._extract_warm_start_value(log)
-        stats: MIPSolveStats = {
+        return MIPSolveStats(
-            "Lower bound": lb,
+            mip_lower_bound=lb,
-            "Upper bound": ub,
+            mip_upper_bound=ub,
-            "Wallclock time": total_wallclock_time,
+            mip_wallclock_time=total_wallclock_time,
-            "Nodes": total_nodes,
+            mip_nodes=total_nodes,
-            "Sense": sense,
+            mip_sense=sense,
-            "MIP log": log,
+            mip_log=log,
-            "Warm start value": ws_value,
+            mip_warm_start_value=ws_value,
-        }
+        )
-        return stats
 
     @overrides
     def get_solution(self) -> Optional[Solution]:

miplearn/solvers/internal.py

@@ -14,7 +14,6 @@ from miplearn.instance.base import Instance
 from miplearn.types import (
     IterationCallback,
     LazyCallback,
-    MIPSolveStats,
     BranchPriorities,
     UserCutCallback,
     Solution,
@@ -31,6 +30,17 @@ class LPSolveStats:
     lp_wallclock_time: Optional[float] = None
 
 
+@dataclass
+class MIPSolveStats:
+    mip_lower_bound: Optional[float]
+    mip_log: str
+    mip_nodes: Optional[int]
+    mip_sense: str
+    mip_upper_bound: Optional[float]
+    mip_wallclock_time: float
+    mip_warm_start_value: Optional[float]
+
+
 class InternalSolver(ABC, EnforceOverrides):
     """
     Abstract class representing the MIP solver used internally by LearningSolver.

miplearn/solvers/learning.py

@@ -240,11 +240,11 @@ class LearningSolver:
             user_cut_cb=user_cut_cb,
             lazy_cb=lazy_cb,
         )
-        stats.update(cast(LearningSolveStats, mip_stats))
+        stats.update(cast(LearningSolveStats, mip_stats.__dict__))
         stats["Solver"] = "default"
         stats["Gap"] = self._compute_gap(
-            ub=stats["Upper bound"],
+            ub=mip_stats.mip_upper_bound,
-            lb=stats["Lower bound"],
+            lb=mip_stats.mip_lower_bound,
         )
         stats["Mode"] = self.mode
 
@@ -256,9 +256,9 @@ class LearningSolver:
 
         # Add some information to training_sample
         # -------------------------------------------------------
-        training_sample.lower_bound = stats["Lower bound"]
+        training_sample.lower_bound = mip_stats.mip_lower_bound
-        training_sample.upper_bound = stats["Upper bound"]
+        training_sample.upper_bound = mip_stats.mip_upper_bound
-        training_sample.mip_log = stats["MIP log"]
+        training_sample.mip_log = mip_stats.mip_log
         training_sample.solution = self.internal_solver.get_solution()
 
         # After-solve callbacks

miplearn/solvers/pyomo/base.py

@@ -136,16 +136,15 @@ class BasePyomoSolver(InternalSolver):
             self._has_mip_solution = True
             lb = results["Problem"][0]["Lower bound"]
             ub = results["Problem"][0]["Upper bound"]
-        stats: MIPSolveStats = {
+        return MIPSolveStats(
-            "Lower bound": lb,
+            mip_lower_bound=lb,
-            "Upper bound": ub,
+            mip_upper_bound=ub,
-            "Wallclock time": total_wallclock_time,
+            mip_wallclock_time=total_wallclock_time,
-            "Sense": self._obj_sense,
+            mip_sense=self._obj_sense,
-            "MIP log": log,
+            mip_log=log,
-            "Nodes": node_count,
+            mip_nodes=node_count,
-            "Warm start value": ws_value,
+            mip_warm_start_value=ws_value,
-        }
+        )
-        return stats
 
     @overrides
     def get_solution(self) -> Optional[Solution]:

miplearn/solvers/tests/__init__.py

@@ -243,11 +243,17 @@ def run_basic_usage_tests(solver: InternalSolver) -> None:
         user_cut_cb=None,
     )
     assert not solver.is_infeasible()
-    assert len(mip_stats["MIP log"]) > 100
+    assert mip_stats.mip_log is not None
-    assert_equals(mip_stats["Lower bound"], 1183.0)
+    assert len(mip_stats.mip_log) > 100
-    assert_equals(mip_stats["Upper bound"], 1183.0)
+    assert mip_stats.mip_lower_bound is not None
-    assert_equals(mip_stats["Sense"], "max")
+    assert_equals(mip_stats.mip_lower_bound, 1183.0)
-    assert isinstance(mip_stats["Wallclock time"], float)
+    assert mip_stats.mip_upper_bound is not None
+    assert_equals(mip_stats.mip_upper_bound, 1183.0)
+    assert mip_stats.mip_sense is not None
+    assert_equals(mip_stats.mip_sense, "max")
+    assert mip_stats.mip_wallclock_time is not None
+    assert isinstance(mip_stats.mip_wallclock_time, float)
+    assert mip_stats.mip_wallclock_time > 0
 
     # Fetch variables (after-load)
     assert_equals(
@@ -325,7 +331,7 @@ def run_basic_usage_tests(solver: InternalSolver) -> None:
 
     # Re-solve MIP and verify that constraint affects the solution
     stats = solver.solve()
-    assert_equals(stats["Lower bound"], 1030.0)
+    assert_equals(stats.mip_lower_bound, 1030.0)
     assert solver.is_constraint_satisfied(cut)
 
     # Remove the new constraint
@@ -333,7 +339,7 @@ def run_basic_usage_tests(solver: InternalSolver) -> None:
 
     # New constraint should no longer affect solution
     stats = solver.solve()
-    assert_equals(stats["Lower bound"], 1183.0)
+    assert_equals(stats.mip_lower_bound, 1183.0)
 
 
 def run_warm_start_tests(solver: InternalSolver) -> None:
@@ -342,17 +348,17 @@ def run_warm_start_tests(solver: InternalSolver) -> None:
     solver.set_instance(instance, model)
     solver.set_warm_start({"x[0]": 1.0, "x[1]": 0.0, "x[2]": 0.0, "x[3]": 1.0})
     stats = solver.solve(tee=True)
-    if stats["Warm start value"] is not None:
+    if stats.mip_warm_start_value is not None:
-        assert_equals(stats["Warm start value"], 725.0)
+        assert_equals(stats.mip_warm_start_value, 725.0)
 
     solver.set_warm_start({"x[0]": 1.0, "x[1]": 1.0, "x[2]": 1.0, "x[3]": 1.0})
     stats = solver.solve(tee=True)
-    assert stats["Warm start value"] is None
+    assert stats.mip_warm_start_value is None
 
     solver.fix({"x[0]": 1.0, "x[1]": 0.0, "x[2]": 0.0, "x[3]": 1.0})
     stats = solver.solve(tee=True)
-    assert_equals(stats["Lower bound"], 725.0)
+    assert_equals(stats.mip_lower_bound, 725.0)
-    assert_equals(stats["Upper bound"], 725.0)
+    assert_equals(stats.mip_upper_bound, 725.0)
 
 
 def run_infeasibility_tests(solver: InternalSolver) -> None:
@@ -361,8 +367,8 @@ def run_infeasibility_tests(solver: InternalSolver) -> None:
     mip_stats = solver.solve()
     assert solver.is_infeasible()
     assert solver.get_solution() is None
-    assert mip_stats["Upper bound"] is None
+    assert mip_stats.mip_upper_bound is None
-    assert mip_stats["Lower bound"] is None
+    assert mip_stats.mip_lower_bound is None
     lp_stats = solver.solve_lp()
     assert solver.get_solution() is None
     assert lp_stats.lp_value is None

miplearn/types.py

@@ -19,30 +19,18 @@ UserCutCallback = Callable[["InternalSolver", Any], None]
 VariableName = str
 Solution = Dict[VariableName, Optional[float]]
 
-MIPSolveStats = TypedDict(
-    "MIPSolveStats",
-    {
-        "Lower bound": Optional[float],
-        "MIP log": str,
-        "Nodes": Optional[int],
-        "Sense": str,
-        "Upper bound": Optional[float],
-        "Wallclock time": float,
-        "Warm start value": Optional[float],
-    },
-)
-
 LearningSolveStats = TypedDict(
     "LearningSolveStats",
     {
         "Gap": Optional[float],
         "Instance": Union[str, int],
-        "LP log": str,
+        "lp_log": str,
-        "LP value": Optional[float],
+        "lp_value": Optional[float],
-        "Lower bound": Optional[float],
+        "lp_wallclock_time": Optional[float],
-        "MIP log": str,
+        "mip_lower_bound": Optional[float],
+        "mip_log": str,
         "Mode": str,
-        "Nodes": Optional[int],
+        "mip_nodes": Optional[int],
         "Objective: Predicted lower bound": float,
         "Objective: Predicted upper bound": float,
         "Primal: Free": int,
@@ -50,9 +38,9 @@ LearningSolveStats = TypedDict(
         "Primal: Zero": int,
         "Sense": str,
         "Solver": str,
-        "Upper bound": Optional[float],
+        "mip_upper_bound": Optional[float],
-        "Wallclock time": float,
+        "mip_wallclock_time": float,
-        "Warm start value": Optional[float],
+        "mip_warm_start_value": Optional[float],
         "LazyStatic: Removed": int,
         "LazyStatic: Kept": int,
         "LazyStatic: Restored": int,

tests/components/test_objective.py

@@ -255,5 +255,5 @@ def test_usage() -> None:
     solver.solve(instance)
     solver.fit([instance])
     stats = solver.solve(instance)
-    assert stats["Lower bound"] == stats["Objective: Predicted lower bound"]
+    assert stats["mip_lower_bound"] == stats["Objective: Predicted lower bound"]
-    assert stats["Upper bound"] == stats["Objective: Predicted upper bound"]
+    assert stats["mip_upper_bound"] == stats["Objective: Predicted upper bound"]

tests/components/test_primal.py

@@ -221,7 +221,7 @@ def test_usage() -> None:
     stats = solver.solve(instance)
     assert stats["Primal: Free"] == 0
     assert stats["Primal: One"] + stats["Primal: Zero"] == 10
-    assert stats["Lower bound"] == stats["Warm start value"]
+    assert stats["mip_lower_bound"] == stats["mip_warm_start_value"]
 
 
 def test_evaluate() -> None:

tests/problems/test_stab.py

@@ -16,7 +16,7 @@ def test_stab() -> None:
     instance = MaxWeightStableSetInstance(graph, weights)
     solver = LearningSolver()
     stats = solver.solve(instance)
-    assert stats["Lower bound"] == 2.0
+    assert stats["mip_lower_bound"] == 2.0
 
 
 def test_stab_generator_fixed_graph() -> None:

tests/problems/test_tsp.py

@@ -47,8 +47,8 @@ def test_instance() -> None:
     assert solution["x[(1, 2)]"] == 1.0
     assert solution["x[(1, 3)]"] == 0.0
     assert solution["x[(2, 3)]"] == 1.0
-    assert stats["Lower bound"] == 4.0
+    assert stats["mip_lower_bound"] == 4.0
-    assert stats["Upper bound"] == 4.0
+    assert stats["mip_upper_bound"] == 4.0
 
 
 def test_subtour() -> None:

tests/solvers/test_learning_solver.py

@@ -140,7 +140,7 @@ def test_simulate_perfect() -> None:
             simulate_perfect=True,
         )
         stats = solver.solve(PickleGzInstance(tmp.name))
-        assert stats["Lower bound"] == stats["Objective: Predicted lower bound"]
+        assert stats["mip_lower_bound"] == stats["Objective: Predicted lower bound"]
 
 
 def test_gap() -> None: