Class IndirectSort

java.lang.Object

com.carrotsearch.hppc.sorting.IndirectSort

public final class IndirectSort
extends Object

Sorting routines that return an array of sorted indices implied by a given comparator rather than move elements of whatever the comparator is using for comparisons.

A practical use case for this class is when the index of an array is meaningful and one wants to acquire the order of values in that array. None of the methods in Java Collections would provide such functionality directly and creating a collection of boxed Integer objects for indices seems to be too costly.

Method Summary

Modifier and Type	Method	Description
static int[]	mergesort(int start, int length, IndirectComparator comparator)	Returns the order of elements between indices start and length, as indicated by the given comparator.
static <T> int[]	mergesort(T[] input, int start, int length, Comparator<? super T> comparator)	Returns the order of elements between indices start and length, as indicated by the given comparator.

Methods inherited from class Object

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

Method Details

mergesort

public static int[] mergesort(int start,
 int length,
 IndirectComparator comparator)

Returns the order of elements between indices start and length, as indicated by the given comparator.

This routine uses merge sort. It is guaranteed to be stable.

mergesort

public static <T> int[] mergesort(T[] input,
 int start,
 int length,
 Comparator<? super T> comparator)

Returns the order of elements between indices start and length, as indicated by the given comparator. This method is equivalent to calling mergesort(int, int, IndirectComparator) with IndirectComparator.DelegatingComparator.

This routine uses merge sort. It is guaranteed to be stable.