Add getLinearConsIndicator (#961)

* Add getLinearConsIndicator

* Add check for NULL return

* Update return type

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 ### Added
+- Added getLinearConsIndicator
 ### Fixed
 ### Changed
 ### Removed

src/pyscipopt/scip.pxd

@@ -1828,6 +1828,7 @@ cdef extern from "scip/cons_indicator.h":
                                      SCIP_Real val)
 
     SCIP_VAR* SCIPgetSlackVarIndicator(SCIP_CONS* cons)
+    SCIP_CONS* SCIPgetLinearConsIndicator(SCIP_CONS* cons)
 
 cdef extern from "scip/misc.h":
     SCIP_RETCODE SCIPhashmapCreate(SCIP_HASHMAP** hashmap, BMS_BLKMEM* blkmem, int mapsize)

src/pyscipopt/scip.pxi

@@ -6229,6 +6229,25 @@ cdef class Model:
         PY_SCIP_CALL(SCIPreleaseCons(self._scip, &scip_cons))
 
         return pyCons
+
+    def getLinearConsIndicator(self, Constraint cons):
+        """
+        Get the linear constraint corresponding to the indicator constraint.
+
+        Parameters
+        ----------
+        cons : Constraint
+            The indicator constraint
+
+        Returns
+        -------
+        Constraint or None
+        """
+
+        cdef SCIP_CONS* lincons = SCIPgetLinearConsIndicator(cons.scip_cons)
+        if lincons == NULL:
+            return None
+        return Constraint.create(lincons)
 
     def getSlackVarIndicator(self, Constraint cons):
         """
@@ -6245,7 +6264,7 @@ cdef class Model:
         Variable
 
         """
-        cdef SCIP_VAR* var = SCIPgetSlackVarIndicator(cons.scip_cons);
+        cdef SCIP_VAR* var = SCIPgetSlackVarIndicator(cons.scip_cons)
         return Variable.create(var)
 
     def addPyCons(self, Constraint cons):

tests/test_cons.py

@@ -118,6 +118,8 @@ def test_cons_indicator():
 
     slack = m.getSlackVarIndicator(c1)
 
+    lin_cons = m.getLinearConsIndicator(c1)
+
     m.optimize()
 
     assert m.getNConss(transformed=False) == 5