edu.ucla.sspace.vector

Class CompactSparseVector

java.lang.Object

edu.ucla.sspace.vector.AbstractVector<Double>

edu.ucla.sspace.vector.AbstractDoubleVector

edu.ucla.sspace.vector.CompactSparseVector

All Implemented Interfaces:

DoubleVector, SparseDoubleVector, SparseVector<Double>, Vector<Double>, Serializable, Iterable<DoubleEntry>

public class CompactSparseVector
extends AbstractDoubleVector
implements SparseDoubleVector, Serializable, Iterable<DoubleEntry>

A Vector instance that keeps only the non-zero values in memory, thereby saving space at the expense of time.

See SparseDoubleArray for details on how the sparse representation is implemented.

Author:

Keith Stevens

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CompactSparseVector() Creates a CompactSparseVector that grows to the maximum size set by Double.MAX_VALUE.
CompactSparseVector(double[] array) Create a CompactSparseVector from an array, saving only the non zero entries.
CompactSparseVector(int length) Create a CompactSparseVector with the given size, having no non-zero values.
CompactSparseVector(int[] nonZeroIndices, double[] values, int length) Create a CompactSparseVector using the indices and their respecitve values.
CompactSparseVector(SparseDoubleVector v) Create a CompactSparseVector from an array, saving only the non zero entries.

Method Summary

Methods

Modifier and Type	Method and Description
double	add(int index, double delta) Throws an UnsupportedOperationException if called (vector is unmodifiable).
double	get(int index) Returns the value of this vector at the given index.
int[]	getNonZeroIndices() Returns all the indices whose values are non-zero
Iterator<DoubleEntry>	iterator() Returns an iterator over all the non-zero indices and values in this vector.
int	length() Return the size of the Vector.
double	magnitude() Returns the magnitude of this vector
void	set(double[] values)
void	set(int index, double value) Throws an UnsupportedOperationException if called (vector is unmodifiable).
double[]	toArray() Returns a double array representing this vector.

Methods inherited from class edu.ucla.sspace.vector.AbstractDoubleVector

equals, getValue, hashCode, set, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.ucla.sspace.vector.DoubleVector

getValue

Methods inherited from interface edu.ucla.sspace.vector.Vector

equals, hashCode, set

Constructor Detail

CompactSparseVector

public CompactSparseVector()

Creates a CompactSparseVector that grows to the maximum size set by Double.MAX_VALUE.

CompactSparseVector

public CompactSparseVector(int length)

Create a CompactSparseVector with the given size, having no non-zero values.

Parameters:

length - The length of this CompactSparseVector.

CompactSparseVector

public CompactSparseVector(double[] array)

Create a CompactSparseVector from an array, saving only the non zero entries.

Parameters:

array - The double array to produce a sparse vector from.

CompactSparseVector

public CompactSparseVector(SparseDoubleVector v)

Create a CompactSparseVector from an array, saving only the non zero entries.

Parameters:

array - The double array to produce a sparse vector from.

CompactSparseVector

public CompactSparseVector(int[] nonZeroIndices,
                   double[] values,
                   int length)

Create a CompactSparseVector using the indices and their respecitve values.

Parameters:

indices - an sorted array of positive values representing the non-zero indices of the array

values - an array of values that correspond their respective indices

length - the total length of the array

Method Detail

add

public double add(int index,
         double delta)

Throws an UnsupportedOperationException if called (vector is unmodifiable).

Specified by:

add in interface DoubleVector

Overrides:

add in class AbstractDoubleVector

Parameters:

index - index to change.

delta - the amount to change by.

Returns:

the resulting value at the index

iterator

public Iterator<DoubleEntry> iterator()

Returns an iterator over all the non-zero indices and values in this vector.

Specified by:

iterator in interface Iterable<DoubleEntry>

get

public double get(int index)

Returns the value of this vector at the given index.

Specified by:

get in interface DoubleVector

Parameters:

index - index to retrieve.

Returns:

value at index.

getNonZeroIndices

public int[] getNonZeroIndices()

Returns all the indices whose values are non-zero

Specified by:

getNonZeroIndices in interface SparseVector<Double>

length

public int length()

Return the size of the Vector.

Specified by:

length in interface Vector<Double>

Returns:

size of the vector.

magnitude

public double magnitude()

Returns the magnitude of this vector

Specified by:

magnitude in interface Vector<Double>

Overrides:

magnitude in class AbstractDoubleVector

set

public void set(double[] values)

set

public void set(int index,
       double value)

Throws an UnsupportedOperationException if called (vector is unmodifiable).

Specified by:

set in interface DoubleVector

Overrides:

set in class AbstractDoubleVector

Parameters:

index - index to set.

value - value to set in the vector.

toArray

public double[] toArray()

Returns a double array representing this vector. The returned array will be "safe" in that no changes to the array will be reflected in the vector, and likewise for changes to to the vector. The caller is thus free to modify the returned array.

Specified by:

toArray in interface DoubleVector

Overrides:

toArray in class AbstractDoubleVector

Returns:

a double array of this vector.