org.apache.sysds.runtime.matrix.data

Class LibMatrixCountDistinct

java.lang.Object

org.apache.sysds.runtime.matrix.data.LibMatrixCountDistinct

public class LibMatrixCountDistinct
extends Object

This class contains various methods for counting the number of distinct values inside a MatrixBlock

Field Summary

Fields

Modifier and Type	Field and Description
static int	minimumSize The minimum number NonZero of cells in the input before using approximate techniques for counting number of distinct values.

Method Summary

Modifier and Type	Method and Description
static int	estimateDistinctValues(MatrixBlock in, CountDistinctOperator op) Public method to count the number of distinct values inside a matrix.

Methods inherited from class java.lang.Object

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

Field Detail

minimumSize

public static int minimumSize

The minimum number NonZero of cells in the input before using approximate techniques for counting number of distinct values.

Method Detail

estimateDistinctValues

public static int estimateDistinctValues(MatrixBlock in,
                                         CountDistinctOperator op)

Public method to count the number of distinct values inside a matrix. Depending on which CountDistinctOperator selected it either gets the absolute number or a estimated value. TODO: Support counting num distinct in rows, or columns axis. TODO: Add support for distributed spark operations TODO: If the MatrixBlock type is CompressedMatrix, simply read the vaules from the ColGroups.

Parameters:

in - the input matrix to count number distinct values in

op - the selected operator to use

Returns:

the distinct count