Add method to evaluate SCIP expressions without variables

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 ### Added
+- Added eval method to evaluate constant expressions
 - Added methods for getting the names of the current stage and of an event
 ### Fixed
 - Fixed outdated time.clock call in gcp.py

src/pyscipopt/scip.pxi

@@ -4671,6 +4671,18 @@ cdef class Model:
             raise Warning("method cannot be called before problem is solved")
         return self.getSolVal(self._bestSol, expr)
 
+    def evalConstantExpression(self, str const):
+        """Evaluates expression without variables
+        :param string const: Constant expression as string"""
+        import math
+        for operation in ["log", "sin", "cos", "exp", "sqrt"]:
+            const = const.replace(operation, "math."+operation)
+        const = const.replace("prod(", "math.prod([")
+        const = const.replace("sum(", "sum([")
+        const = const.replace("))", ")])]")
+
+        return eval(const)
+
     def hasPrimalRay(self):
         """
         Returns whether a primal ray is stored that proves unboundedness of the LP relaxation

tests/test_model.py

@@ -286,3 +286,11 @@ def test_getStage():
     print(m.getStage())
     assert m.getStage() == SCIP_STAGE.SOLVED
     assert m.getStageName() == "SOLVED"
+
+def test_eval():
+    import math
+    m = Model()
+
+    assert m.isEQ(math.log(2), m.evalConstantExpression("log(2)"))
+    assert m.isEQ(sum([21.68,math.prod([0.007446285387417584,sum([996.47,math.prod([-1.0,math.exp(1.234317963583726),math.log(1.42)])])])]) ,m.evalConstantExpression("sum(21.68,prod(0.007446285387417584,sum(996.47,prod(-1.0,exp(1.234317963583726),log(1.42)))))"))
+