org.terrier.utility

Class HeapSort

java.lang.Object

org.terrier.utility.HeapSort

public class HeapSort
extends Object

An implementation of the heap sort algorithm as described in Cormen et al. Introduction to Algorithms. This class sorts two arrays, with respect to the values of the elements in the first array. There is also an option to sort only N entries with the highest values. In this case, there are two options:

• The top N entries can be sorted in ascending order, so that the N elements with the highest values are placed in the array's last N positions (the highest entry of the arrays will be in array[array.length-1], the second highest in array[array.length-2] and so on.
• The top N entries can be sorted in descending order, so that the N elements with the highest values are placed in the array's first N positions (the highest entry of the array will be in array[0], the second highest entry will be in array[1] and so on.

Author:

Vassilis Plachouras

Constructor Summary

Constructors

Constructor and Description
HeapSort()

Method Summary

Methods

Modifier and Type	Method and Description
static void	ascendingHeapSort(double[] A, int[] B, short[] C) Sorts the given arrays in ascending order, using heap-sort.
static void	ascendingHeapSort(double[] A, int[] B, short[] C, int topElements) Sorts the top topElements of the given array in ascending order, using heap sort.
static void	descendingHeapSort(double[] A, int[] B, short[] C) Sorts the given arrays in descending order, using heap-sort.
static void	descendingHeapSort(double[] A, int[] B, short[] C, int topElements) Sorts the top topElements of the given array in descending order, using heap sort for sorting the values in ascending order and then reversing the order of a specified number of elements.

Methods inherited from class java.lang.Object

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

Constructor Detail

HeapSort

public HeapSort()

Method Detail

ascendingHeapSort

public static final void ascendingHeapSort(double[] A,
                     int[] B,
                     short[] C)

Sorts the given arrays in ascending order, using heap-sort.

Parameters:

A - double[] the first array to be sorted.

B - int[] the second array to be sorted, according to the values of the first array.

descendingHeapSort

public static final void descendingHeapSort(double[] A,
                      int[] B,
                      short[] C)

Sorts the given arrays in descending order, using heap-sort.

Parameters:

A - double[] the first array to be sorted.

B - int[] the second array to be sorted, according to the values of the first array.

ascendingHeapSort

public static final void ascendingHeapSort(double[] A,
                     int[] B,
                     short[] C,
                     int topElements)

Sorts the top topElements of the given array in ascending order, using heap sort.

Parameters:

A - double[] the first array to be sorted.

B - int[] the second array to be sorted, according to the values of the first array.

topElements - int the number of elements to be sorted.

descendingHeapSort

public static final void descendingHeapSort(double[] A,
                      int[] B,
                      short[] C,
                      int topElements)

Sorts the top topElements of the given array in descending order, using heap sort for sorting the values in ascending order and then reversing the order of a specified number of elements.

Parameters:

A - double[] the first array to be sorted.

B - int[] the second array to be sorted, according to the values of the first array.

topElements - int the number of elements to be sorted.