Package org.apache.jackrabbit.commons.flat

Class Rank<T>

  • Type Parameters:
    T - Type of values in this Rank.
    public class Rank<T>
extends java.lang.Object

    This class does efficient ranking of values of type T wrt. to a Comparator for T. After creating an instance of Rank, the take(int) method returns the next k smallest values. That is, each of these values is smaller than every value not yet retrieved. The order of the values returned by take is not specified in general. However if the values are in increasing order, the values returned by take will also be in increasing order.

    Note: The values may not contain duplicates or the behavior of take is not defined.

    • Constructor Summary

      Constructors 
      Constructor Description
      Rank​(java.util.Collection<T> values, java.lang.Class<T> componentType, java.util.Comparator<? super T> order)
      Create a new instance of Rank for a given collection of values and a given order.
      Rank​(java.util.Iterator<T> values, java.lang.Class<T> componentType, int count, java.util.Comparator<? super T> order)
      Create a new instance of Rank for the first count values in a a given iterator of values and a given order.
      Rank​(T[] values, java.util.Comparator<? super T> order)
      Create a new instance of Rank for a given array of values and a given order.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static <T extends java.lang.Comparable<T>>
      java.util.Comparator<T>      		 comparableComparator()
      Utility method for creating a Comparator of T from a Comparable of type T.
      java.util.Comparator<? super T> getOrder()  
      static <S extends java.lang.Comparable<S>>
      Rank<S>      		 rank​(java.util.Collection<S> values, java.lang.Class<S> componentType)
      Create a new instance of Rank for a given collection of values.
      static <S extends java.lang.Comparable<S>>
      Rank<S>      		 rank​(java.util.Iterator<S> values, java.lang.Class<S> componentType, int count)
      Create a new instance of Rank for the first count values in a a given iterator of values.
      static <S extends java.lang.Comparable<S>>
      Rank<S>      		 rank​(S[] values)
      Create a new instance of Rank for a given array of values.
      int size()
      Returns the number of remaining items in the Rank.
      java.util.Iterator<T> take​(int n)
      Returns the n-th smallest values remaining in this Rank.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Rank

        public Rank​(T[] values,
            java.util.Comparator<? super T> order)
        Create a new instance of Rank for a given array of values and a given order. The values are manipulated in place, no copying is performed.
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        order - Ordering for ranking

      • Rank

        public Rank​(java.util.Collection<T> values,
            java.lang.Class<T> componentType,
            java.util.Comparator<? super T> order)
        Create a new instance of Rank for a given collection of values and a given order. The values are copied into an internal array before they are manipulated.
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        componentType - type evidence for the values
        order - Ordering for ranking

      • Rank

        public Rank​(java.util.Iterator<T> values,
            java.lang.Class<T> componentType,
            int count,
            java.util.Comparator<? super T> order)
        Create a new instance of Rank for the first count values in a a given iterator of values and a given order. The values are copied into an internal array before they are manipulated.
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        componentType - type evidence for the values
        count - Number of items to include. -1 for all.
        order - Ordering for ranking

    • Method Detail

      • rank

        public static <S extends java.lang.Comparable<S>> Rank<S> rank​(S[] values)
        Create a new instance of Rank for a given array of values. The order is determined by the natural ordering of the values (i.e. through Comparable). The values are manipulated in place, no copying is performed.
        Type Parameters:
        S - extends Comparable<S>
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        Returns:
        A new instance of Rank.

      • rank

        public static <S extends java.lang.Comparable<S>> Rank<S> rank​(java.util.Collection<S> values,
                                                               java.lang.Class<S> componentType)
        Create a new instance of Rank for a given collection of values. The order is determined by the natural ordering of the values (i.e. through Comparable). The values are copied into an internal array before they are manipulated.
        Type Parameters:
        S - extends Comparable<S>
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        componentType - type evidence for the values
        Returns:
        A new instance of Rank.

      • rank

        public static <S extends java.lang.Comparable<S>> Rank<S> rank​(java.util.Iterator<S> values,
                                                               java.lang.Class<S> componentType,
                                                               int count)
        Create a new instance of Rank for the first count values in a a given iterator of values. The order is determined by the natural ordering of the values (i.e. through Comparable). The values are copied into an internal array before they are manipulated.
        Type Parameters:
        S - extends Comparable<S>
        Parameters:
        values - values for ranking. Duplicates are not allowed.
        componentType - type evidence for the values
        count - Number of items to include. -1 for all.
        Returns:
        A new instance of Rank.

      • comparableComparator

        public static <T extends java.lang.Comparable<T>> java.util.Comparator<T> comparableComparator()
        Utility method for creating a Comparator of T from a Comparable of type T.
        Type Parameters:
        T - extends Comparable<T>
        Returns:
        Comparator whose order is defined by T.

      • getOrder

        public java.util.Comparator<? super T> getOrder()

      • take

        public java.util.Iterator<T> take​(int n)
        Returns the n-th smallest values remaining in this Rank.
        Parameters:
        n - Number of values to return
        Returns:
        An iterator containing the next n smallest values.
        Throws:
        java.util.NoSuchElementException - if this Rank has not enough remaining elements or when n is negative.

      • size

        public int size()
        Returns the number of remaining items in the Rank.
        Returns:
        number of remaining items.