Class PartialPermutation

  • All Implemented Interfaces:
    Partial<Permutation>

    public final class PartialPermutation
    extends Object
    implements Partial<Permutation>

    A PartialPermutation represents a permutation that is being iteratively constructed as a solution to an optimization problem over the space of permutations. This class supports the implementation of constructive heuristics for permutation optimization problems, as well as for stochastic sampling algorithms that rely on constructive heuristics.

    In the context of this library, a permutation of length n is a permutation of the integers { 0, 1, ..., (n-1)}.

    • Constructor Summary

      Constructors 
      Constructor Description
      PartialPermutation​(int n)
      Constructs a PartialPermutation that will iteratively be transformed into a Permutation.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void extend​(int extensionIndex)
      Extends the Partial by adding an element to the end of the Partial.
      int get​(int index)
      Gets the element in the Partial at position index.
      int getExtension​(int extensionIndex)
      Gets the element in position index of the list of possible extensions.
      int getLast()
      Gets the element in the current last position of the Partial, i.e., the element at index: size()-1.
      boolean isComplete()
      Checks if the Partial is actually a complete T.
      int numExtensions()
      Gets the number of elements not yet added to the Partial.
      int size()
      Gets the size of the Partial, which is the number of elements that have already been added to it.
      Permutation toComplete()
      Generates a complete instance that is consistent with this Partial.
    • Constructor Detail

      • PartialPermutation

        public PartialPermutation​(int n)
        Constructs a PartialPermutation that will iteratively be transformed into a Permutation.
        Parameters:
        n - The desired length of the final Permutation, which must be non-negative.
        Throws:
        IllegalArgumentException - if n is less than 0
    • Method Detail

      • toComplete

        public Permutation toComplete()
        Description copied from interface: Partial
        Generates a complete instance that is consistent with this Partial. That is, elements already added to the Partial will retain their positions, while elements not already in the Partial will be added in an undefined order such that the result is a valid complete object of type T.
        Specified by:
        toComplete in interface Partial<Permutation>
        Returns:
        a valid object of type T consistent with the current state of this Partial
      • isComplete

        public boolean isComplete()
        Description copied from interface: Partial
        Checks if the Partial is actually a complete T.
        Specified by:
        isComplete in interface Partial<Permutation>
        Returns:
        true if the Partial is a complete T.
      • get

        public int get​(int index)
        Description copied from interface: Partial
        Gets the element in the Partial at position index.
        Specified by:
        get in interface Partial<Permutation>
        Parameters:
        index - The position, which must be less than size(). The valid index values are [0, 1, ..., (size()-1)].
        Returns:
        the element in position index.
      • getLast

        public int getLast()
        Description copied from interface: Partial
        Gets the element in the current last position of the Partial, i.e., the element at index: size()-1.
        Specified by:
        getLast in interface Partial<Permutation>
        Returns:
        The element in the current last position of the Partial.
      • size

        public int size()
        Description copied from interface: Partial
        Gets the size of the Partial, which is the number of elements that have already been added to it. Note that this is NOT the size of the final complete T. Rather, it is the current size of the Partial.
        Specified by:
        size in interface Partial<Permutation>
        Returns:
        size The size of the Partial.
      • numExtensions

        public int numExtensions()
        Description copied from interface: Partial
        Gets the number of elements not yet added to the Partial. We refer to these as extensions since adding an element will extend the size of the Partial.
        Specified by:
        numExtensions in interface Partial<Permutation>
        Returns:
        the number of elements not yet added to the Partial
      • getExtension

        public int getExtension​(int extensionIndex)
        Description copied from interface: Partial
        Gets the element in position index of the list of possible extensions. This method gets the element at position index from the list of those elements that can be added next to the Partial. For example, if this is a partial permutation, then this would get one of the elements not yet added to the permutation. Or for example, if this is a partial vector of integers, then this would get one of the values that is allowed to be added to the next position of the vector. Note that each time Partial.extend(int) is called that the remaining elements may be reordered, so you cannot assume that the extensions remain in the same positions once you call extend.
        Specified by:
        getExtension in interface Partial<Permutation>
        Parameters:
        extensionIndex - An index into the list of elements that can be added to the Partial next. The valid extensionIndex values are [0, 1, ..., (numExtensions()-1)].
        Returns:
        the element at the designated index in the list of elements that can be added to the Partial.
      • extend

        public void extend​(int extensionIndex)
        Description copied from interface: Partial

        Extends the Partial by adding an element to the end of the Partial. If size() is the size of the Partial before the extension, then the new element is added to position size() and the size() is increased by 1.

        Specified by:
        extend in interface Partial<Permutation>
        Parameters:
        extensionIndex - An index into the list of elements that can be added to the Partial. The valid extensionIndex values are [0, 1, ..., (numExtensions()-1)].