pyscipopt style

Author: Joao-Dionisio

src/pyscipopt/scip.pxi

@@ -2665,20 +2665,55 @@ cdef class _VarArray:
 
 cdef class IIS:
     cdef SCIP_IIS* _iis
-    cdef SCIP* subscip
-    cdef public object time
-    cdef public object irreducible
-    cdef public object nodes
-    cdef public object model
 
     def __init__(self, Model model):
         self._iis = SCIPgetIIS(model._scip)
-        self.time = SCIPiisGetTime(self._iis)
-        self.irreducible = SCIPiisIsSubscipIrreducible(self._iis)
-        self.nodes = SCIPiisGetNNodes(self._iis)
-        subscip = SCIPiisGetSubscip(self._iis)
-        self.model = Model.create(subscip)
         model._iis = self._iis
+    
+    def getTime(self):
+        """
+        Retrieve the solving time of the IIS.
+
+        Returns
+        -------
+        float
+        """
+        return SCIPiisGetTime(self._iis)
+
+    def isSubscipIrreducible(self):
+        """
+        Returns whether the IIS is irreducible.
+
+        Returns
+        -------
+        bool
+        """
+        return SCIPiisIsSubscipIrreducible(self._iis)
+    
+    def getNNodes(self):
+        """
+        Gets number of nodes in the IIS solve.
+
+        Returns
+        -------
+        int
+
+        """
+        return SCIPiisGetNNodes(self._iis)
+    
+    def getSubscip(self):
+        """
+        Get the subscip of an IIS.
+
+        Returns
+        -------
+        Model
+        """
+        cdef SCIP* subscip
+
+        subscip = SCIPiisGetSubscip(self._iis)
+        model = Model.create(subscip)
+        return model
 
 # - remove create(), includeDefaultPlugins(), createProbBasic() methods
 # - replace free() by "destructor"

tests/test_iis.py

@@ -19,12 +19,15 @@ def infeasible_model():
 def test_generate_iis():
     m = infeasible_model()
 
+    m.optimize()
+
     # make sure IIS generation doesn't raise any exceptions
     iis = m.generateIIS()
-    assert iis.irreducible
-    assert iis.model.getNConss() == 2
-    assert iis.nodes == 0
-    iis.time
+    subscip = iis.getSubscip()
+    assert iis.isSubscipIrreducible()
+    assert subscip.getNConss() == 2
+    assert iis.getNNodes() == 0
+    assert iis.getTime() > 0
 
 class myIIS(IISfinder):
     def __init__(self, model, skip=False):
@@ -50,21 +53,22 @@ def test_custom_iis_finder():
     m = infeasible_model()
     my_iis = myIIS(m)
 
+    m.setParam("iis/greedy/priority", -1)
     m.includeIISfinder(my_iis, "", "")
 
     m.generateIIS()
     iis = m.getIIS()
-    assert iis.model.getNConss() == my_iis.size
+    subscip = iis.getSubscip()
+    assert subscip.getNConss() == my_iis.size
 
 def test_iisGreddyMakeIrreducible():
     m = infeasible_model()
 
-    m.setParam("iis/greedy/priority", -1)
     my_iis = myIIS(m, skip=True)
-    m.includeIISfinder(my_iis, "", "")
+    m.includeIISfinder(my_iis, "", "", priority=9999999)
     iis = m.generateIIS()
     with pytest.raises(AssertionError):
-        assert not iis.irreducible # currently breaking. do SCIP IIS methods enter after custom iisfinder?
+        assert not iis.isSubscipIrreducible() # currently breaking. do SCIP IIS methods enter after custom iisfinder?
 
     m.iisGreedyMakeIrreducible(iis)
-    assert iis.irreducible
+    assert iis.isSubscipIrreducible()