Add getNBranchings and getNBranchingsCurrentRun (#1049)

* getNBranchings and getNBranchingsCurrentRun

* Fix imports

* Update src/pyscipopt/scip.pxi

Co-authored-by: João Dionísio <[email protected]>

* Update src/pyscipopt/scip.pxi

Co-authored-by: João Dionísio <[email protected]>

* Tests improved

* Update test_vars.py

---------

Co-authored-by: João Dionísio <[email protected]>

Author: sirenard

CHANGELOG.md

@@ -14,6 +14,7 @@
 - Added recipe for getting local constraints
 - Added enableDebugSol() and disableDebugSol() for controlling the debug solution mechanism if DEBUGSOL=true
 - Added getVarPseudocostScore() and getVarPseudocost()
+- Added getNBranchings() and getNBranchingsCurrentRun()
 ### Fixed
 - Raised an error when an expression is used when a variable is required
 - Fixed some compile warnings

src/pyscipopt/scip.pxd

@@ -813,6 +813,7 @@ cdef extern from "scip/scip.h":
     SCIP_Real SCIPgetVarPseudocostScore(SCIP* scip, SCIP_VAR* var, SCIP_Real solval)
     SCIP_Real SCIPvarGetCutoffSum(SCIP_VAR* var, SCIP_BRANCHDIR dir)
     SCIP_Longint SCIPvarGetNBranchings(SCIP_VAR* var, SCIP_BRANCHDIR dir)
+    SCIP_Longint SCIPvarGetNBranchingsCurrentRun(SCIP_VAR* var, SCIP_BRANCHDIR dir)
     SCIP_Bool SCIPvarMayRoundUp(SCIP_VAR* var)
     SCIP_Bool SCIPvarMayRoundDown(SCIP_VAR* var)
 

src/pyscipopt/scip.pxi

@@ -1804,6 +1804,37 @@ cdef class Variable(Expr):
             mayround = SCIPvarMayRoundUp(self.scip_var)
         return mayround
 
+    def getNBranchings(self, branchdir):
+        """
+        returns the number of times a bound of the variable was changed in given direction due to branching
+
+        Parameters
+        ----------
+        branchdir : PY_SCIP_BRANCHDIR
+            branching direction (downwards, or upwards)
+
+        Returns
+        -------
+        int
+        """
+        return SCIPvarGetNBranchings(self.scip_var, branchdir)
+
+    def getNBranchingsCurrentRun(self, branchdir):
+        """
+        returns the number of times a bound of the variable was changed in given direction due to branching in the
+        current run
+
+        Parameters
+        ----------
+        branchdir : PY_SCIP_BRANCHDIR
+            branching direction (downwards, or upwards)
+
+        Returns
+        -------
+        int
+        """
+        return SCIPvarGetNBranchingsCurrentRun(self.scip_var, branchdir)
+
 class MatrixVariable(MatrixExpr):
 
     def vtype(self):

tests/test_vars.py

@@ -1,4 +1,7 @@
-from pyscipopt import Model
+from pyscipopt import Model, SCIP_PARAMSETTING, SCIP_BRANCHDIR
+
+from tests.helpers.utils import random_mip_1
+
 
 def test_variablebounds():
 
@@ -80,3 +83,34 @@ def test_markRelaxationOnly():
     assert x.isDeletable()
     assert not y.isRelaxationOnly()
     assert not y.isDeletable()
+
+def test_getNBranchings():
+    m = random_mip_1(True, True, True, 100, True)
+    m.setParam("branching/mostinf/priority", 999999)
+    m.setParam("limits/restarts", 0)
+
+    m.optimize()
+
+    m.setParam("limits/nodes", 200)
+    m.restartSolve()
+    m.optimize()
+
+    n_branchings = 0
+    for var in m.getVars():
+        n_branchings += var.getNBranchings(SCIP_BRANCHDIR.UPWARDS)
+        n_branchings += var.getNBranchings(SCIP_BRANCHDIR.DOWNWARDS)
+
+    assert n_branchings == m.getNTotalNodes() - 2 # "-2" comes from the two root nodes because of the restart
+
+def test_getNBranchingsCurrentRun():
+    m = random_mip_1(True, True, True, 100, True)
+    m.setParam( "branching/mostinf/priority", 999999)
+
+    m.optimize()
+
+    n_branchings = 0
+    for var in m.getVars():
+        n_branchings += var.getNBranchingsCurrentRun(SCIP_BRANCHDIR.UPWARDS)
+        n_branchings += var.getNBranchingsCurrentRun(SCIP_BRANCHDIR.DOWNWARDS)
+
+    assert n_branchings == m.getNNodes() - 1