Better default name for indicator cons

Author: Joao-Dionisio

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added stage checks to presolve, freereoptsolve, freetransform
 - Added primal_dual_evolution recipe and a plot recipe
 ### Fixed
+- Fixed default name for indicator constraints
 ### Changed
 ### Removed
 

src/pyscipopt/scip.pxi

@@ -5330,7 +5330,7 @@ cdef class Model:
 
         return pyCons
 
-    def addConsIndicator(self, cons, binvar=None, activeone=True, name="IndicatorCons",
+    def addConsIndicator(self, cons, binvar=None, activeone=True, name="",
                 initial=True, separate=True, enforce=True, check=True,
                 propagate=True, local=False, dynamic=False,
                 removable=False, stickingatnode=False):
@@ -5348,7 +5348,7 @@ cdef class Model:
         activeone : bool, optional
             constraint should active if binvar is 1 (0 if activeone = False)
         name : str, optional
-            name of the constraint (Default value = "IndicatorCons")
+            name of the constraint (Default value = "")
         initial : bool, optional
             should the LP relaxation of constraint be in the initial LP? (Default value = True)
         separate : bool, optional
@@ -5381,6 +5381,9 @@ cdef class Model:
         if cons._lhs is not None and cons._rhs is not None:
             raise ValueError("expected inequality that has either only a left or right hand side")
 
+        if name == '':
+            name = 'c'+str(SCIPgetNConss(self._scip)+1)
+
         if cons.expr.degree() > 1:
             raise ValueError("expected linear inequality, expression has degree %d" % cons.expr.degree())
 

tests/test_cons.py

@@ -101,20 +101,33 @@ def test_SOScons():
 
 def test_cons_indicator():
     m = Model()
-    x = m.addVar(lb=0)
+    x = m.addVar(lb=0, obj=1)
     binvar = m.addVar(vtype="B", lb=1)
 
-    c = m.addConsIndicator(x >= 1, binvar)
+    c1 = m.addConsIndicator(x >= 1, binvar) 
 
-    slack = m.getSlackVarIndicator(c)
+    assert c1.name == "c1"
+
+    c2 = m.addCons(x <= 3)
+
+    c3 = m.addConsIndicator(x >= 0, binvar)
+    assert c3.name == "c4"
+
+    # because addConsIndicator actually adds two constraints
+    assert m.getNConss() == 5
+
+    slack = m.getSlackVarIndicator(c1)
 
     m.optimize()
 
+    assert m.getNConss() == 5
     assert m.isEQ(m.getVal(slack), 0)
     assert m.isEQ(m.getVal(binvar), 1)
     assert m.isEQ(m.getVal(x), 1)
-    assert c.getConshdlrName() == "indicator"
+    assert c1.getConshdlrName() == "indicator"
+
 
+test_cons_indicator()
 
 @pytest.mark.xfail(
     reason="addConsIndicator doesn't behave as expected when binary variable is False. See Issue #717."