Make InternalSolver clonable

miplearn/solvers/pyomo/base.py

@@ -46,6 +46,7 @@ class BasePyomoSolver(InternalSolver):
     ) -> None:
         self.instance: Optional[Instance] = None
         self.model: Optional[pe.ConcreteModel] = None
+        self.params = params
         self._all_vars: List[pe.Var] = []
         self._bin_vars: List[pe.Var] = []
         self._is_warm_start_available: bool = False

miplearn/solvers/pyomo/cplex.py

@@ -28,8 +28,7 @@ class CplexPyomoSolver(BasePyomoSolver):
     ) -> None:
         if params is None:
             params = {}
-        if "randomseed" not in params.keys():
-            params["randomseed"] = randint(low=0, high=1000).rvs()
+        params["randomseed"] = randint(low=0, high=1000).rvs()
         if "mip_display" not in params.keys():
             params["mip_display"] = 4
         super().__init__(
@@ -44,3 +43,7 @@ class CplexPyomoSolver(BasePyomoSolver):
     @overrides
     def _get_node_count_regexp(self):
         return "^[ *] *([0-9]+)"
+
+    @overrides
+    def clone(self) -> "CplexPyomoSolver":
+        return CplexPyomoSolver(params=self.params)

miplearn/solvers/pyomo/gurobi.py

@@ -32,8 +32,7 @@ class GurobiPyomoSolver(BasePyomoSolver):
     ) -> None:
         if params is None:
             params = {}
-        if "seed" not in params.keys():
-            params["seed"] = randint(low=0, high=1000).rvs()
+        params["seed"] = randint(low=0, high=1000).rvs()
         super().__init__(
             solver_factory=pe.SolverFactory("gurobi_persistent"),
             params=params,
@@ -61,3 +60,7 @@ class GurobiPyomoSolver(BasePyomoSolver):
             var = self._varname_to_var[varname]
             gvar = self._pyomo_solver._pyomo_var_to_solver_var_map[var]
             gvar.setAttr(GRB.Attr.BranchPriority, int(round(priority)))
+
+    @overrides
+    def clone(self) -> "GurobiPyomoSolver":
+        return GurobiPyomoSolver(params=self.params)

miplearn/solvers/pyomo/xpress.py

@@ -4,6 +4,7 @@
 
 import logging
 
+from overrides import overrides
 from pyomo import environ as pe
 from scipy.stats import randint
 
@@ -27,9 +28,12 @@ class XpressPyomoSolver(BasePyomoSolver):
     def __init__(self, params: SolverParams = None) -> None:
         if params is None:
             params = {}
-        if "randomseed" not in params.keys():
-            params["randomseed"] = randint(low=0, high=1000).rvs()
+        params["randomseed"] = randint(low=0, high=1000).rvs()
         super().__init__(
             solver_factory=pe.SolverFactory("xpress_persistent"),
             params=params,
         )
+
+    @overrides
+    def clone(self) -> "XpressPyomoSolver":
+        return XpressPyomoSolver(params=self.params)