org.grouplens.lenskit.vectors

Class Vec

java.lang.Object

org.grouplens.lenskit.vectors.Vec

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

ImmutableVec, MutableVec

public abstract class Vec
extends Object
implements Serializable

A real vector. This is a read-only view of a vector of doubles. It is backed by an array, and contains values associated with indices [0,size()).

Since:

1.3

See Also:

Serialized Form

Method Summary

Methods

Modifier and Type	Method and Description
double	dot(Vec other) Compute the dot product of this vector with another.
boolean	equals(Object o)
double	get(int i) Get the value from the vector at the specified position.
int	hashCode()
ImmutableVec	immutable() Get an immutable vector with this vector's contents.
double	mean() Get the mean of this vector.
MutableVec	mutableCopy() Get a mutable copy of this vector.
double	norm() Get the L2 (Euclidean) norm of this vector.
int	size() Get the dimension of this vector (the number of elements).
double	sum() Get the sum of this vector.

Methods inherited from class java.lang.Object

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

Method Detail

get

public final double get(int i)

Get the value from the vector at the specified position.

Parameters:

i - The index into the vector.

Returns:

The value at index i.

Throws:

IllegalArgumentException - if i is not in the range [0,size()).

size

public final int size()

Get the dimension of this vector (the number of elements).

Returns:

The number of elements in the vector.

norm

public double norm()

Get the L2 (Euclidean) norm of this vector.

Returns:

The Euclidean length of the vector.

sum

public double sum()

Get the sum of this vector.

Returns:

The sum of the elements of the vector.

mean

public double mean()

Get the mean of this vector.

Returns:

The mean of the elements of the vector (or Double.NaN if the vector is empty).

dot

public final double dot(Vec other)

Compute the dot product of this vector with another.

Parameters:

other - The other vector.

Returns:

The dot product of this vector and other.

Throws:

IllegalArgumentException - if other.size() != this.size().

immutable

public ImmutableVec immutable()

Get an immutable vector with this vector's contents. If the vector is already immutable, it is not changed.

Returns:

The immutable vector.

mutableCopy

public MutableVec mutableCopy()

Get a mutable copy of this vector.

Returns:

A mutable copy of this vector.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object