Package org.openscience.cdk.group

Class Partition

  • public class Partition
extends Object
    A partition of a set of integers, such as the discrete partition {{1}, {2}, {3}, {4}} or the unit partition {{1, 2, 3, 4}} or an intermediate like {{1, 2}, {3, 4}}.
    Author:
    maclean
    Belongs to CDK module:
    group

    • Constructor Summary

      Constructors 
      Constructor Description
      Partition()
      Creates a new, empty partition with no cells.
      Partition​(int[][] cellData)
      Constructor to make a partition from an array of int arrays.
      Partition​(Partition other)
      Copy constructor to make one partition from another.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addCell​(int... elements)
      Adds a new cell to the end of the partition containing these elements.
      void addCell​(Collection<Integer> elements)
      Adds a new cell to the end of the partition.
      void addSingletonCell​(int element)
      Add a new singleton cell to the end of the partition containing only this element.
      void addToCell​(int index, int element)
      Add an element to a particular cell.
      SortedSet<Integer> copyBlock​(int cellIndex)
      Creates and returns a copy of the cell at cell index.
      boolean equals​(Object o)
      static Partition fromString​(String strForm)
      Parse a string like "[0,2|1,3]" to form the partition; cells are separated by '|' characters and elements within the cell by commas.
      SortedSet<Integer> getCell​(int cellIndex)
      Gets the cell at this index.
      int getFirstInCell​(int cellIndex)
      Gets the first element in the specified cell.
      int getIndexOfFirstNonDiscreteCell()
      Gets the index of the first cell in the partition that is discrete.
      int hashCode()
      boolean inOrder()
      Check whether the cells are ordered such that for cells i and j, first(j) > first(i) and last(j) > last(i).
      boolean inSameCell​(int elementI, int elementJ)
      Check that two elements are in the same cell of the partition.
      void insertCell​(int index, SortedSet<Integer> cell)
      Insert a cell into the partition at the specified index.
      boolean isDiscrete()
      Checks that all the cells are singletons - that is, they only have one element.
      boolean isDiscreteCell​(int cellIndex)
      Check to see if the cell at cellIndex is discrete - that is, it only has one element.
      int numberOfElements()
      Calculate the size of the partition as the sum of the sizes of the cells.
      void order()
      Sort the cells in increasing order.
      void removeCell​(int index)
      Removes the cell at the specified index.
      Permutation setAsPermutation​(int upTo)
      Fill the elements of a permutation from the first element of each cell, up to the point upTo.
      int size()
      Gets the size of the partition, in terms of the number of cells.
      Partition splitAfter​(int cellIndex, int splitElement)
      Splits this partition by taking the cell at cellIndex and making two new cells - the first with the the rest of the elements from that cell and the second with the singleton splitElement.
      Partition splitBefore​(int cellIndex, int splitElement)
      Splits this partition by taking the cell at cellIndex and making two new cells - the first with the singleton splitElement and the second with the rest of the elements from that cell.
      Permutation toPermutation()
      Converts the whole partition into a permutation.
      String toString()
      static Partition unit​(int size)
      Create a unit partition - in other words, the coarsest possible partition where all the elements are in one cell.

    • Constructor Detail

      • Partition

        public Partition()
        Creates a new, empty partition with no cells.

      • Partition

        public Partition​(Partition other)
        Copy constructor to make one partition from another.
        Parameters:
        other - the partition to copy

      • Partition

        public Partition​(int[][] cellData)
        Constructor to make a partition from an array of int arrays.
        Parameters:
        cellData - the partition to copy

    • Method Detail

      • unit

        public static Partition unit​(int size)
        Create a unit partition - in other words, the coarsest possible partition where all the elements are in one cell.
        Parameters:
        size - the number of elements
        Returns:
        a new Partition with one cell containing all the elements

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class Object

      • size

        public int size()
        Gets the size of the partition, in terms of the number of cells.
        Returns:
        the number of cells in the partition

      • numberOfElements

        public int numberOfElements()
        Calculate the size of the partition as the sum of the sizes of the cells.
        Returns:
        the number of elements in the partition

      • isDiscrete

        public boolean isDiscrete()
        Checks that all the cells are singletons - that is, they only have one element. A discrete partition is equivalent to a permutation.
        Returns:
        true if all the cells are discrete

      • toPermutation

        public Permutation toPermutation()
        Converts the whole partition into a permutation.
        Returns:
        the partition as a permutation

      • inOrder

        public boolean inOrder()
        Check whether the cells are ordered such that for cells i and j, first(j) > first(i) and last(j) > last(i).
        Returns:
        true if all cells in the partition are ordered

      • getFirstInCell

        public int getFirstInCell​(int cellIndex)
        Gets the first element in the specified cell.
        Parameters:
        cellIndex - the cell to use
        Returns:
        the first element in this cell

      • getCell

        public SortedSet<Integer> getCell​(int cellIndex)
        Gets the cell at this index.
        Parameters:
        cellIndex - the index of the cell to return
        Returns:
        the cell at this index

      • splitBefore

        public Partition splitBefore​(int cellIndex,
                             int splitElement)
        Splits this partition by taking the cell at cellIndex and making two new cells - the first with the singleton splitElement and the second with the rest of the elements from that cell.
        Parameters:
        cellIndex - the index of the cell to split on
        splitElement - the element to put in its own cell
        Returns:
        a new (finer) Partition

      • splitAfter

        public Partition splitAfter​(int cellIndex,
                            int splitElement)
        Splits this partition by taking the cell at cellIndex and making two new cells - the first with the the rest of the elements from that cell and the second with the singleton splitElement.
        Parameters:
        cellIndex - the index of the cell to split on
        splitElement - the element to put in its own cell
        Returns:
        a new (finer) Partition

      • setAsPermutation

        public Permutation setAsPermutation​(int upTo)
        Fill the elements of a permutation from the first element of each cell, up to the point upTo.
        Parameters:
        upTo - take values from cells up to this one
        Returns:
        the permutation representing the first element of each cell

      • isDiscreteCell

        public boolean isDiscreteCell​(int cellIndex)
        Check to see if the cell at cellIndex is discrete - that is, it only has one element.
        Parameters:
        cellIndex - the index of the cell to check
        Returns:
        true of the cell at this index is discrete

      • getIndexOfFirstNonDiscreteCell

        public int getIndexOfFirstNonDiscreteCell()
        Gets the index of the first cell in the partition that is discrete.
        Returns:
        the index of the first discrete cell

      • addSingletonCell

        public void addSingletonCell​(int element)
        Add a new singleton cell to the end of the partition containing only this element.
        Parameters:
        element - the element to add in its own cell

      • removeCell

        public void removeCell​(int index)
        Removes the cell at the specified index.
        Parameters:
        index - the index of the cell to remove

      • addCell

        public void addCell​(int... elements)
        Adds a new cell to the end of the partition containing these elements.
        Parameters:
        elements - the elements to add in a new cell

      • addCell

        public void addCell​(Collection<Integer> elements)
        Adds a new cell to the end of the partition.
        Parameters:
        elements - the collection of elements to put in the cell

      • addToCell

        public void addToCell​(int index,
                      int element)
        Add an element to a particular cell.
        Parameters:
        index - the index of the cell to add to
        element - the element to add

      • insertCell

        public void insertCell​(int index,
                       SortedSet<Integer> cell)
        Insert a cell into the partition at the specified index.
        Parameters:
        index - the index of the cell to add
        cell - the cell to add

      • copyBlock

        public SortedSet<Integer> copyBlock​(int cellIndex)
        Creates and returns a copy of the cell at cell index.
        Parameters:
        cellIndex - the cell to copy
        Returns:
        the copy of the cell

      • order

        public void order()
        Sort the cells in increasing order.

      • inSameCell

        public boolean inSameCell​(int elementI,
                          int elementJ)
        Check that two elements are in the same cell of the partition.
        Parameters:
        elementI - an element in the partition
        elementJ - an element in the partition
        Returns:
        true if both elements are in the same cell

      • fromString

        public static Partition fromString​(String strForm)
        Parse a string like "[0,2|1,3]" to form the partition; cells are separated by '|' characters and elements within the cell by commas.
        Parameters:
        strForm - the partition in string form
        Returns:
        the partition corresponding to the string
        Throws:
        IllegalArgumentException - thrown if the provided strFrom is null or empty