smile.sort

Class HeapSelect<T extends java.lang.Comparable<? super T>>

java.lang.Object

smile.sort.HeapSelect<T>

public class HeapSelect<T extends java.lang.Comparable<? super T>>
extends java.lang.Object

This class tracks the smallest values seen thus far in a stream of values. This implements a single-pass selection for large data sets. That is, we have a stream of input values, each of which we get to see only once. We want to be able to report at any time, say after n values, the i-th smallest value see so far.

Constructor Summary

Constructors

Constructor and Description
HeapSelect(java.lang.Class clazz, int k) Constructor.
HeapSelect(T[] heap) Constructor.

Method Summary

Modifier and Type	Method and Description
void	add(T datum) Assimilate a new value from the stream.
T	get(int i) Returns the i-th smallest value seen so far.
void	heapify() In case of avoiding creating new objects frequently, one may check and update the peek object directly and call this method to sort the internal array in heap order.
T	peek() Returns the k-th smallest value seen so far.
int	size() Returns the number of objects that have been added into heap.
void	sort() Sort the smallest values.
T[]	toArray() Returns the array back the heap.
T[]	toArray(T[] a) Returns the array back the heap.

Methods inherited from class java.lang.Object

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

Constructor Detail

HeapSelect

public HeapSelect(java.lang.Class clazz,
                  int k)

Constructor.

Parameters:

clazz - the data type of elements.

k - the size of heap.

HeapSelect

public HeapSelect(T[] heap)

Constructor.

Parameters:

heap - the array to store smallest values to track.

Method Detail

size

public int size()

Returns the number of objects that have been added into heap.

toArray

public T[] toArray()

Returns the array back the heap.

toArray

public T[] toArray(T[] a)

Returns the array back the heap.

add

public void add(T datum)

Assimilate a new value from the stream.

heapify

public void heapify()

In case of avoiding creating new objects frequently, one may check and update the peek object directly and call this method to sort the internal array in heap order.

peek

public T peek()

Returns the k-th smallest value seen so far.

get

public T get(int i)

Returns the i-th smallest value seen so far. i = 0 returns the smallest value seen, i = 1 the second largest, ..., i = k-1 the last position tracked. Also, i must be less than the number of previous assimilated.

sort

public void sort()

Sort the smallest values.