org.apache.arrow.algorithm.sort

Class IndexSorter<V extends ValueVector>

java.lang.Object

org.apache.arrow.algorithm.sort.IndexSorter<V>

Type Parameters:

V - vector type.

public class IndexSorter<V extends ValueVector>
extends Object

Sorter for the indices of a vector.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CHANGE_ALGORITHM_THRESHOLD If the number of items is smaller than this threshold, we will use another algorithm to sort the data.

Constructor Summary

Constructors

Constructor and Description
IndexSorter()

Method Summary

Modifier and Type	Method and Description
static <T extends ValueVector> int	partition(int low, int high, IntVector indices, VectorValueComparator<T> comparator) Partition a range of values in a vector into two parts, with elements in one part smaller than elements from the other part.
void	sort(V vector, IntVector indices, VectorValueComparator<V> comparator) Sorts indices, by quick-sort.

Methods inherited from class java.lang.Object

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

Field Detail

CHANGE_ALGORITHM_THRESHOLD

public static final int CHANGE_ALGORITHM_THRESHOLD

If the number of items is smaller than this threshold, we will use another algorithm to sort the data.

See Also:

Constant Field Values

Constructor Detail

IndexSorter

public IndexSorter()

Method Detail

sort

public void sort(V vector,
                 IntVector indices,
                 VectorValueComparator<V> comparator)

Sorts indices, by quick-sort. Suppose the vector is denoted by v. After calling this method, the following relations hold: v(indices[0]) <= v(indices[1]) <= ...

Parameters:

vector - the vector whose indices need to be sorted.

indices - the vector for storing the sorted indices.

comparator - the comparator to sort indices.

partition

public static <T extends ValueVector> int partition(int low,
                                                    int high,
                                                    IntVector indices,
                                                    VectorValueComparator<T> comparator)

Partition a range of values in a vector into two parts, with elements in one part smaller than elements from the other part. The partition is based on the element indices, so it does not modify the underlying vector.

Type Parameters:

T - the vector type.

Parameters:

low - the lower bound of the range.

high - the upper bound of the range.

indices - vector element indices.

comparator - criteria for comparison.

Returns:

the index of the split point.