Relax stage for checking getObjVal, getVal (#872)

* Set correct stages. Add SCIPsolIsOriginal

* Add test for getObjVal

* Remove noexcept

* Update changelog

* Add noexcept again

* Add everything back

* Segfault commit

* Update CHANGELOG

* Add test

* Relax stage checks

* Update test_customizedbenders.py

* Update variable name

Author: Joao-Dionisio

CHANGELOG.md

@@ -5,6 +5,25 @@
 - Created Statistics class
 - Added parser to read .stats file
 ### Fixed
+- Fixed too strict getObjVal, getVal check
+### Changed
+### Removed
+
+## 5.1.1 - 2024-06-22
+### Added
+- Added SCIP_STATUS_DUALLIMIT and SCIP_STATUS_PRIMALLIMIT
+- Added SCIPprintExternalCodes (retrieves version of linked symmetry, lp solver, nl solver etc)
+- Added recipe with reformulation for detecting infeasible constraints
+- Wrapped SCIPcreateOrigSol and added tests 
+- Added verbose option for writeProblem and writeParams
+- Expanded locale test
+- Added methods for creating expression constraints without adding to problem
+- Added methods for creating/adding/appending disjunction constraints
+- Added check for pt_PT locale in test_model.py
+- Added SCIPgetOrigConss and SCIPgetNOrigConss Cython bindings. 
+- Added transformed=False option to getConss, getNConss, and getNVars
+### Fixed
+- Fixed locale errors in reading
 ### Changed
 ### Removed
 

src/pyscipopt/scip.pxd

@@ -839,6 +839,7 @@ cdef extern from "scip/scip.h":
     int SCIPgetNBestSolsFound(SCIP* scip)
     SCIP_SOL* SCIPgetBestSol(SCIP* scip)
     SCIP_Real SCIPgetSolVal(SCIP* scip, SCIP_SOL* sol, SCIP_VAR* var)
+    SCIP_Bool SCIPsolIsOriginal(SCIP_SOL* sol)
     SCIP_RETCODE SCIPwriteVarName(SCIP* scip, FILE* outfile, SCIP_VAR* var, SCIP_Bool vartype)
     SCIP_Real SCIPgetSolOrigObj(SCIP* scip, SCIP_SOL* sol)
     SCIP_Real SCIPgetSolTransObj(SCIP* scip, SCIP_SOL* sol)

src/pyscipopt/scip.pxi

@@ -627,7 +627,9 @@ cdef class Solution:
 
     def _checkStage(self, method):
         if method in ["SCIPgetSolVal", "getSolObjVal"]:
-            if self.sol == NULL and SCIPgetStage(self.scip) != SCIP_STAGE_SOLVING:
+            stage_check = SCIPgetStage(self.scip) not in [SCIP_STAGE_INIT, SCIP_STAGE_FREE]
+
+            if not stage_check or self.sol == NULL and SCIPgetStage(self.scip) != SCIP_STAGE_SOLVING:
                 raise Warning(f"{method} can only be called with a valid solution or in stage SOLVING (current stage: {SCIPgetStage(self.scip)})")
 
 
@@ -3543,6 +3545,7 @@ cdef class Model:
     def presolve(self):
         """Presolve the problem."""
         PY_SCIP_CALL(SCIPpresolve(self._scip))
+        self._bestSol = Solution.create(self._scip, SCIPgetBestSol(self._scip))
 
     # Benders' decomposition methods
     def initBendersDefault(self, subproblems):
@@ -3606,7 +3609,7 @@ cdef class Model:
                 PY_SCIP_CALL(SCIPsetupBendersSubproblem(self._scip,
                     _benders[i], self._bestSol.sol, j, SCIP_BENDERSENFOTYPE_CHECK))
                 PY_SCIP_CALL(SCIPsolveBendersSubproblem(self._scip,
-                    _benders[i], self._bestSol.sol, j, &_infeasible, solvecip, NULL))
+                    _benders[i], self._bestSol.sol, j, &_infeasible, solvecip, NULL))                
 
     def freeBendersSubproblems(self):
         """Calls the free subproblem function for the Benders' decomposition.
@@ -4838,11 +4841,14 @@ cdef class Model:
         """
         if sol == None:
             sol = Solution.create(self._scip, NULL)
+
         sol._checkStage("getSolObjVal")
+
         if original:
             objval = SCIPgetSolOrigObj(self._scip, sol.sol)
         else:
             objval = SCIPgetSolTransObj(self._scip, sol.sol)
+
         return objval
 
     def getSolTime(self, Solution sol):
@@ -4855,13 +4861,24 @@ cdef class Model:
 
     def getObjVal(self, original=True):
         """Retrieve the objective value of value of best solution.
-        Can only be called after solving is completed.
 
         :param original: objective value in original space (Default value = True)
-
         """
-        if not self.getStage() >= SCIP_STAGE_SOLVING:
-            raise Warning("method cannot be called before problem is solved")
+
+        if SCIPgetNSols(self._scip) == 0:
+            if self.getStage() != SCIP_STAGE_SOLVING:
+                raise Warning("Without a solution, method can only be called in stage SOLVING.")
+        else:
+            assert self._bestSol.sol != NULL
+            
+            if SCIPsolIsOriginal(self._bestSol.sol):
+                min_stage_requirement = SCIP_STAGE_PROBLEM
+            else:
+                min_stage_requirement = SCIP_STAGE_TRANSFORMING
+
+            if not self.getStage() >= min_stage_requirement:
+                raise Warning("method cannot be called in stage %i." % self.getStage)
+
         return self.getSolObjVal(self._bestSol, original)
 
     def getSolVal(self, Solution sol, Expr expr):
@@ -4889,8 +4906,11 @@ cdef class Model:
 
         Note: a variable is also an expression
         """
-        if not self.getStage() >= SCIP_STAGE_SOLVING:
-            raise Warning("method cannot be called before problem is solved")
+        stage_check = SCIPgetStage(self._scip) not in [SCIP_STAGE_INIT, SCIP_STAGE_FREE]
+
+        if not stage_check or self._bestSol.sol == NULL and SCIPgetStage(self._scip) != SCIP_STAGE_SOLVING:
+            raise Warning("Method cannot be called in stage ", self.getStage())
+
         return self.getSolVal(self._bestSol, expr)
 
     def hasPrimalRay(self):

tests/test_cons.py

@@ -72,7 +72,6 @@ def test_cons_logical():
     assert m.isEQ(m.getVal(result1), 1)
     assert m.isEQ(m.getVal(result2), 0)
 
-
 def test_SOScons():
     m = Model()
     x = {}

tests/test_customizedbenders.py

@@ -54,7 +54,7 @@ def bendersgetvar(self, variable, probnumber):
     def benderssolvesubconvex(self, solution, probnumber, onlyconvex):
         self.model.setupBendersSubproblem(probnumber, self, solution)
         self.subprob.solveProbingLP()
-        subprob = self.model.getBendersSubproblem(probnumber, self)
+        subprob = self.model.getBendersSubproblem(probnumber, self)  
         assert self.subprob.getObjVal() == subprob.getObjVal()
 
         result_dict = {}

tests/test_model.py

@@ -435,3 +435,45 @@ def build_scip_model():
     scip.setParam("limits/dual", -10)
     scip.optimize()
     assert (scip.getStatus() == "duallimit"), scip.getStatus()
+
+def test_getObjVal():
+    m = Model()
+
+    x = m.addVar(obj=0)
+    y = m.addVar(obj = 1)
+    z = m.addVar(obj = 2)
+
+    m.addCons(x+y+z >= 0)
+    m.addCons(y+z >= 3)
+    m.addCons(z >= 8)
+
+    m.setParam("limits/solutions", 0)
+    m.optimize()
+    
+    try:
+        m.getObjVal()
+    except Warning:
+        pass
+
+    try:
+        m.getVal(x)
+    except Warning:
+        pass
+
+    m.freeTransform()
+    m.setParam("limits/solutions", 1)
+    m.presolve()
+
+    assert m.getObjVal()
+    assert m.getVal(x)
+
+    m.freeTransform()
+    m.setParam("limits/solutions", -1)
+
+    m.optimize()
+
+    assert m.getObjVal() == 16 
+    assert m.getVal(x) == 0
+
+    assert m.getObjVal() == 16 
+    assert m.getVal(x) == 0