org.apache.mahout.math
Class VectorView

java.lang.Object
  org.apache.mahout.math.AbstractVector
      org.apache.mahout.math.VectorView

All Implemented Interfaces:

Cloneable, Iterable<Vector.Element>, Vector

public class VectorView
extends AbstractVector

Implements subset view of a Vector

Nested Class Summary

class	VectorView.AllIterator
class	VectorView.NonZeroIterator

Nested classes/interfaces inherited from class org.apache.mahout.math.AbstractVector

AbstractVector.LocalElement

Nested classes/interfaces inherited from interface org.apache.mahout.math.Vector

Vector.Element

Field Summary

Fields inherited from class org.apache.mahout.math.AbstractVector

lengthSquared

Constructor Summary

VectorView()
For serialization purposes only

VectorView(Vector vector, int offset, int cardinality)

Method Summary

Vector	clone() Return a copy of the recipient
double	getDistanceSquared(Vector v) Get the square of the distance between this vector and the other vector.
double	getLengthSquared() Return the sum of squares of all elements in the vector.
int	getNumNondefaultElements() Return the number of values in the recipient which are not the default value.
double	getQuick(int index) Return the value at the given index, without checking bounds
boolean	isDense()
boolean	isSequentialAccess()
Iterator<Vector.Element>	iterateNonZero() Iterates over all non-zero elements.
Iterator<Vector.Element>	iterator() Iterates over all elements * NOTE: Implementations may choose to reuse the Element returned for performance reasons, so if you need a copy of it, you should call Vector.getElement(int) for the given index
VectorView	like() Return an empty vector of the same underlying class as the receiver
protected Matrix	matrixLike(int rows, int columns) Subclasses must override to return an appropriately sparse or dense result
void	setQuick(int index, double value) Set the value at the given index, without checking bounds
Vector	viewPart(int offset, int length) Return a new vector containing the subset of the recipient

Methods inherited from class org.apache.mahout.math.AbstractVector

aggregate, aggregate, asFormatString, assign, assign, assign, assign, assign, assign, cross, divide, dot, dotSelf, equals, get, getElement, hashCode, logNormalize, logNormalize, logNormalize, maxValue, maxValueIndex, minus, minValue, minValueIndex, norm, normalize, normalize, plus, plus, set, size, times, times, toString, toString, zSum

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

VectorView

public VectorView()

For serialization purposes only

VectorView

public VectorView(Vector vector,
                  int offset,
                  int cardinality)

Method Detail

matrixLike

protected Matrix matrixLike(int rows,
                            int columns)

Description copied from class: AbstractVector

Subclasses must override to return an appropriately sparse or dense result

Specified by:

matrixLike in class AbstractVector

Parameters:

rows - the row cardinality

columns - the column cardinality

Returns:

a Matrix

clone

public Vector clone()

Description copied from interface: Vector

Return a copy of the recipient

Specified by:

clone in interface Vector

Overrides:

clone in class AbstractVector

Returns:

a new Vector

isDense

public boolean isDense()

Returns:

true iff this implementation should be considered dense -- that it explicitly represents every value

isSequentialAccess

public boolean isSequentialAccess()

Returns:

true iff this implementation should be considered to be iterable in index order in an efficient way. In particular this implies that Vector.iterator() and Vector.iterateNonZero() return elements in ascending order by index.

like

public VectorView like()

Description copied from interface: Vector

Return an empty vector of the same underlying class as the receiver

Returns:

a Vector

getQuick

public double getQuick(int index)

Description copied from interface: Vector

Return the value at the given index, without checking bounds

Parameters:

index - an int index

Returns:

the double at the index

setQuick

public void setQuick(int index,
                     double value)

Description copied from interface: Vector

Set the value at the given index, without checking bounds

Parameters:

index - an int index into the receiver

value - a double value to set

getNumNondefaultElements

public int getNumNondefaultElements()

Description copied from interface: Vector

Return the number of values in the recipient which are not the default value. For instance, for a sparse vector, this would be the number of non-zero values.

Returns:

an int

viewPart

public Vector viewPart(int offset,
                       int length)

Description copied from interface: Vector

Return a new vector containing the subset of the recipient

Specified by:

viewPart in interface Vector

Overrides:

viewPart in class AbstractVector

Parameters:

offset - an int offset into the receiver

length - the cardinality of the desired result

Returns:

a new Vector

iterateNonZero

public Iterator<Vector.Element> iterateNonZero()

Description copied from interface: Vector

Iterates over all non-zero elements.

NOTE: Implementations may choose to reuse the Element returned for performance reasons, so if you need a copy of it, you should call Vector.getElement(int) for the given index

Returns:

An Iterator over all non-zero elements

iterator

public Iterator<Vector.Element> iterator()

Description copied from interface: Vector

Iterates over all elements

* NOTE: Implementations may choose to reuse the Element returned for performance reasons, so if you need a copy of it, you should call Vector.getElement(int) for the given index

Returns:

An Iterator over all elements

getLengthSquared

public double getLengthSquared()

Description copied from interface: Vector

Return the sum of squares of all elements in the vector. Square root of this value is the length of the vector.

Specified by:

getLengthSquared in interface Vector

Overrides:

getLengthSquared in class AbstractVector

getDistanceSquared

public double getDistanceSquared(Vector v)

Description copied from interface: Vector

Get the square of the distance between this vector and the other vector.

Specified by:

getDistanceSquared in interface Vector

Overrides:

getDistanceSquared in class AbstractVector