edu.princeton.cs.algs4

Class Vector

java.lang.Object

edu.princeton.cs.algs4.Vector

public class Vector
extends java.lang.Object

The Vector class represents a d-dimensional Euclidean vector. Vectors are immutable: their values cannot be changed after they are created. It includes methods for addition, subtraction, dot product, scalar product, unit vector, Euclidean norm, and the Euclidean distance between two vectors.

For additional documentation, see Section 1.2 of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.

Constructor Summary

Constructors

Constructor and Description
Vector(double... a) Initializes a vector from either an array or a vararg list.
Vector(int d) Initializes a d-dimensional zero vector.

Method Summary

Modifier and Type	Method and Description
double	cartesian(int i) Returns the ith cartesian coordinate.
int	dimension() Returns the dimension of this vector.
Vector	direction() Returns a unit vector in the direction of this vector.
double	distanceTo(Vector that) Returns the Euclidean distance between this vector and the specified vector.
double	dot(Vector that) Returns the do product of this vector with the specified vector.
int	length() Deprecated. Replaced by dimension().
double	magnitude() Returns the magnitude of this vector.
static void	main(java.lang.String[] args) Unit tests the Vector data type.
Vector	minus(Vector that) Returns the difference between this vector and the specified vector.
Vector	plus(Vector that) Returns the sum of this vector and the specified vector.
Vector	scale(double alpha) Returns the scalar-vector product of this vector and the specified scalar
Vector	times(double alpha) Deprecated. Replaced by scale(double).
java.lang.String	toString() Returns a string representation of this vector.

Methods inherited from class java.lang.Object

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

Constructor Detail

Vector

public Vector(int d)

Initializes a d-dimensional zero vector.

Parameters:

d - the dimension of the vector

Vector

public Vector(double... a)

Initializes a vector from either an array or a vararg list. The vararg syntax supports a constructor that takes a variable number of arugments such as Vector x = new Vector(1.0, 2.0, 3.0, 4.0).

Parameters:

a - the array or vararg list

Method Detail

length

@Deprecated
public int length()

Deprecated. Replaced by dimension().

Returns the length of this vector.

Returns:

the dimension of this vector

dimension

public int dimension()

Returns the dimension of this vector.

Returns:

the dimension of this vector

dot

public double dot(Vector that)

Returns the do product of this vector with the specified vector.

Parameters:

that - the other vector

Returns:

the dot product of this vector and that vector

Throws:

java.lang.IllegalArgumentException - if the dimensions of the two vectors are not equal

magnitude

public double magnitude()

Returns the magnitude of this vector. This is also known as the L2 norm or the Euclidean norm.

Returns:

the magnitude of this vector

distanceTo

public double distanceTo(Vector that)

Returns the Euclidean distance between this vector and the specified vector.

Parameters:

that - the other vector

Returns:

the Euclidean distance between this vector and that vector

Throws:

java.lang.IllegalArgumentException - if the dimensions of the two vectors are not equal

plus

public Vector plus(Vector that)

Returns the sum of this vector and the specified vector.

Parameters:

that - the vector to add to this vector

Returns:

the vector whose value is (this + that)

Throws:

java.lang.IllegalArgumentException - if the dimensions of the two vectors are not equal

minus

public Vector minus(Vector that)

Returns the difference between this vector and the specified vector.

Parameters:

that - the vector to subtract from this vector

Returns:

the vector whose value is (this - that)

Throws:

java.lang.IllegalArgumentException - if the dimensions of the two vectors are not equal

cartesian

public double cartesian(int i)

Returns the ith cartesian coordinate.

Parameters:

i - the coordinate index

Returns:

the ith cartesian coordinate

times

@Deprecated
public Vector times(double alpha)

Deprecated. Replaced by scale(double).

Returns the scalar-vector product of this vector and the specified scalar

Parameters:

alpha - the scalar

Returns:

the vector whose value is (alpha * this)

scale

public Vector scale(double alpha)

Returns the scalar-vector product of this vector and the specified scalar

Parameters:

alpha - the scalar

Returns:

the vector whose value is (alpha * this)

direction

public Vector direction()

Returns a unit vector in the direction of this vector.

Returns:

a unit vector in the direction of this vector

Throws:

java.lang.ArithmeticException - if this vector is the zero vector

toString

public java.lang.String toString()

Returns a string representation of this vector.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this vector, which consists of the the vector entries, separates by single spaces

main

public static void main(java.lang.String[] args)

Unit tests the Vector data type.

Parameters:

args - the command-line arguments