Package org.jacop.constraints.binpacking

Class Binpacking

java.lang.Object
org.jacop.constraints.DecomposedConstraint<Constraint>
org.jacop.constraints.Constraint
org.jacop.constraints.binpacking.Binpacking
All Implemented Interfaces:
SatisfiedPresent, Stateful, UsesQueueVariable
public class Binpacking extends Constraint implements UsesQueueVariable, Stateful, SatisfiedPresent
Binpacking constraint implements bin packing problem. It ensures that items are packed into bins while respecting cpacity constraints of each bin.

This implementation is based on paper "A Constraint for Bin Packing" by Paul Shaw, CP 2004.

This constraint is not idempotent (does not compute fix-point) and, in case when another computation for fix-point is needed, it adds itself to the constraint queue.

Version:
4.10

  • Field Details

    • idNumber

      private static final AtomicInteger idNumber

    • item

      public final BinItem[] item
      It keeps together a list of variables which define bin for item i and their weigts.

    • load

      public final IntVar[] load
      It specifies a list of variables which define bin load.

    • firstConsistencyCheck

      private boolean firstConsistencyCheck

    • minBinNumber

      private int minBinNumber

    • sizeAllItems

      private int sizeAllItems

    • alphaP

      private int alphaP

    • betaP

      private int betaP

    • itemQueue

      private final SimpleHashSet<IntVar> itemQueue

    • binQueue

      private final SimpleHashSet<IntVar> binQueue

    • itemMap

      private final Map<IntVar,Integer> itemMap

    • binMap

      private final Map<IntVar,Integer> binMap

    • LBpruning

      boolean LBpruning

    • LBpruningStamp

      private TimeStamp<Boolean> LBpruningStamp

    • LBnumber

      static long LBnumber

  • Constructor Details

    • Binpacking

      public Binpacking(IntVar[] bin, IntVar[] load, int[] w)
      It constructs the binpacking constraint for the supplied variable.
      Parameters:
      bin - which are constrained to define bin for item i.
      load - which are constrained to define load for bin i.
      w - which define size ofitem i.

    • Binpacking

      public Binpacking(List<? extends IntVar> bin, List<? extends IntVar> load, int[] w)
      It constructs the binpacking constraint for the supplied variable.
      Parameters:
      bin - which are constrained to define bin for item i.
      load - which are constrained to define load for bin i.
      w - which define size ofitem i.

    • Binpacking

      public Binpacking(IntVar[] bin, IntVar[] load, int[] w, int minBin)
      It constructs the binpacking constraint for the supplied variable.
      Parameters:
      bin - which are constrained to define bin for item i.
      load - which are constrained to define load for bin i.
      w - which define size ofitem i.
      minBin - minimal index of a bin; ovewrite the value provided by minimal index of variable bin

    • Binpacking

      public Binpacking(List<? extends IntVar> bin, List<? extends IntVar> load, int[] w, int minBin)
      It constructs the binpacking constraint for the supplied variable.
      Parameters:
      bin - which are constrained to define bin for item i.
      load - which are constrained to define load for bin i.
      w - which define size ofitem i.
      minBin - minimal index of a bin; ovewrite the value provided by minimal index of variable bin

    • Binpacking

      public Binpacking(IntVar[] bin, IntVar[] load, int[] w, int minBin, boolean LBpruning)

  • Method Details

    • impose

      public void impose(Store store)
      Description copied from class: Constraint
      It imposes the constraint in a given store.
      Overrides:
      impose in class Constraint
      Parameters:
      store - the constraint store to which the constraint is imposed to.

    • consistency

      public void consistency(Store store)
      Description copied from class: Constraint
      It is a (most probably incomplete) consistency function which removes the values from variables domains. Only values which do not have any support in a solution space are removed.
      Specified by:
      consistency in class Constraint
      Parameters:
      store - constraint store within which the constraint consistency is being checked.

    • lbNumberBins

      void lbNumberBins()

    • getNumberBins

      private int getNumberBins(BinItem[] item)

    • merge

      private int[] merge(int[] a, int aLength, int[] b)

    • getDefaultConsistencyPruningEvent

      public int getDefaultConsistencyPruningEvent()
      Specified by:
      getDefaultConsistencyPruningEvent in class Constraint

    • satisfied

      public boolean satisfied()
      Description copied from interface: SatisfiedPresent
      It checks if the constraint is satisfied. It can return false even if constraint is satisfied but not all variables in its scope are grounded. It needs to return true if all variables in its scope are grounded and constraint is satisfied.

      Implementations of this interface for constraints that are not PrimitiveConstraint may require constraint imposition and consistency check as a requirement to work correctly.

      Specified by:
      satisfied in interface SatisfiedPresent
      Returns:
      true if constraint is possible to verify that it is satisfied.

    • queueVariable

      public void queueVariable(int level, Var var)
      Description copied from class: Constraint
      This is a function called to indicate which variable in a scope of constraint has changed. It also indicates a store level at which the change has occurred.
      Overrides:
      queueVariable in class Constraint
      Parameters:
      level - the level of the store at which the change has occurred.
      var - variable which has changed.

    • removeLevel

      public void removeLevel(int level)
      Description copied from interface: Stateful
      This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid. This function is called *before* all timestamps, variables, mutablevariables have reverted to their previous value.
      Specified by:
      removeLevel in interface Stateful
      Parameters:
      level - the level which is being removed.

    • toString

      public String toString()
      Description copied from class: Constraint
      It produces a string representation of a constraint state.
      Overrides:
      toString in class Constraint

    • no_sum

      private boolean no_sum(int[] x, int alpha, int beta)

    • sum

      private int sum(int[] x)

    • lbBins

      private void lbBins(int[] x, int C, int nb)