jsat.linear

Class Poly2Vec

java.lang.Object

jsat.linear.Vec

jsat.linear.Poly2Vec

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<IndexValue>

public class Poly2Vec
extends Vec

This class is used to create an implicit representation of the degree 2 polynomial of an input vector, with an implicit bias term added so that the original vector values are present in the implicit vector. This means no extra memory will be allocated, and all values accessed will be re-computed as needed. This works with sparse vectors, and work bet with algorithms that iterate over the nonzero values once.

Any change in the base vector will change the values in this vector. Because changing one value in the base effects multiple values in this one, altering this vector directly is not allowed.

If the base vector has N non zero values, then this vec will have O(N²) non zero values. (N+2)(N+1)/2 non zero values to be exact.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Poly2Vec(Vec base)

Method Summary

Modifier and Type	Method and Description
Vec	clone()
double	get(int index) Gets the value stored at a specific index in the vector
java.util.Iterator<IndexValue>	getNonZeroIterator(int start) Returns an iterator that will go over the non zero values starting from the specified index in the given vector.
boolean	isSparse() Indicates whether or not this vector is optimized for sparce computation, meaning that most values in the vector are zero - and considered implicit.
int	length() Returns the length of this vector
int	nnz() Computes the number of non zero values in this vector
void	set(int index, double val) Sets the value stored at a specified index in the vector
void	setBase(Vec base) Creates a new vector that implicitly represents the degree 2 polynomial of the base vector.

Methods inherited from class jsat.linear.Vec

add, add, applyFunction, applyIndexFunction, arrayCopy, canBeMutated, copyTo, copyToCol, copyToRow, countNaNs, divide, dot, equals, equals, getNonZeroIterator, hashCode, increment, iterator, kurtosis, max, mean, median, min, multiply, multiply, multiply, multiply, mutableAdd, mutableAdd, mutableAdd, mutableDivide, mutableMultiply, mutablePairwiseDivide, mutablePairwiseMultiply, mutableSubtract, mutableSubtract, mutableSubtract, normalize, normalized, pairwiseDivide, pairwiseMultiply, pNorm, pNormDist, random, random, skewness, sortedCopy, standardDeviation, subtract, subtract, sum, toString, variance, zeroOut, zeros

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

Poly2Vec

public Poly2Vec(Vec base)

Method Detail

setBase

public void setBase(Vec base)

Creates a new vector that implicitly represents the degree 2 polynomial of the base vector.

Parameters:

base - the base vector

length

public int length()

Description copied from class: Vec

Returns the length of this vector

Specified by:

length in class Vec

Returns:

the length of this vector

nnz

public int nnz()

Description copied from class: Vec

Computes the number of non zero values in this vector

Overrides:

nnz in class Vec

Returns:

the number of non zero values stored

get

public double get(int index)

Description copied from class: Vec

Gets the value stored at a specific index in the vector

Specified by:

get in class Vec

Parameters:

index - the index to access

Returns:

the double value in the vector

set

public void set(int index,
                double val)

Description copied from class: Vec

Sets the value stored at a specified index in the vector

Specified by:

set in class Vec

Parameters:

index - the index to access

val - the value to store in the index

isSparse

public boolean isSparse()

Description copied from class: Vec

Indicates whether or not this vector is optimized for sparce computation, meaning that most values in the vector are zero - and considered implicit. Only non-zero values are stored.

Specified by:

isSparse in class Vec

Returns:

true if the vector is sparce, false otherwise.

clone

public Vec clone()

Specified by:

clone in class Vec

getNonZeroIterator

public java.util.Iterator<IndexValue> getNonZeroIterator(int start)

Description copied from class: Vec

Returns an iterator that will go over the non zero values starting from the specified index in the given vector. The iterator does not support the Iterator.remove() method.

This method should be overloaded for a serious implementation.

Overrides:

getNonZeroIterator in class Vec

Parameters:

start - the first index (inclusive) to start returning non-zero values from

Returns:

an iterator for the non zero index value pairs