Class PolarCoordinates

java.lang.Object
org.apache.commons.geometry.euclidean.twod.PolarCoordinates
All Implemented Interfaces:
Spatial
public final class PolarCoordinates extends Object implements Spatial
Class representing polar coordinates in 2 dimensional Euclidean space.

Polar coordinates are defined by a distance from a reference point and an angle from a reference direction. The distance value is called the radial coordinate, or radius, and the angle is called the angular coordinate, or azimuth. This class follows the standard mathematical convention of using the positive x-axis as the reference direction and measuring positive angles counter-clockwise, toward the positive y-axis. The origin is used as the reference point. Polar coordinate are related to Cartesian coordinates as follows: 

 x = r * cos(θ)
 y = r * sin(θ)

 r = √(x^2 + y^2)
 θ = atan2(y, x)
where r is the radius and θ is the azimuth of the polar coordinates.

In order to ensure the uniqueness of coordinate sets, coordinate values are normalized so that radius is in the range [0, +Infinity) and azimuth is in the range [0, 2pi).

See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private final double
    azimuth
    Azimuth angle in radians.
    private final double
    radius
    Radius value.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    PolarCoordinates(double radius, double azimuth)
    Simple constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    equals(Object other)
    Test for the equality of two sets of polar coordinates.
    static PolarCoordinates
    fromCartesian(double x, double y)
    Convert the given Cartesian coordinates to polar form.
    static PolarCoordinates
    fromCartesian(Vector2D vec)
    Convert the given Cartesian coordinates to polar form.
    double
    getAzimuth()
    Return the azimuth angle in radians.
    int
    getDimension()
    Returns the number of dimensions in the space that this element belongs to.
    double
    getRadius()
    Return the radius value.
    int
    hashCode()
    Get a hashCode for this set of polar coordinates.
    boolean
    isFinite()
    Returns true if all values in this element are finite, meaning they are not NaN or infinite.
    boolean
    isInfinite()
    Returns true if any value in this element is infinite and none are NaN; otherwise, returns false.
    boolean
    isNaN()
    Returns true if any value in this element is NaN; otherwise returns false.
    static double
    normalizeAzimuth(double azimuth)
    Normalize an azimuth value to be within the range [0, 2pi).
    static PolarCoordinates
    of(double radius, double azimuth)
    Return a new instance with the given polar coordinate values.
    static PolarCoordinates
    parse(String input)
    Parse the given string and return a new polar coordinates instance.
    Vector2D
    toCartesian()
    Convert this set of polar coordinates to Cartesian coordinates.
    static Vector2D
    toCartesian(double radius, double azimuth)
    Convert the given polar coordinates to Cartesian form.
    String
    toString()

    Methods inherited from class Object

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

  • Field Details

    • radius

      private final double radius
      Radius value.

    • azimuth

      private final double azimuth
      Azimuth angle in radians.

  • Constructor Details

    • PolarCoordinates

      private PolarCoordinates(double radius, double azimuth)
      Simple constructor. Input values are normalized.
      Parameters:
      radius - Radius value.
      azimuth - Azimuth angle in radians.

  • Method Details

    • getRadius

      public double getRadius()
      Return the radius value. The value will be greater than or equal to 0.
      Returns:
      radius value

    • getAzimuth

      public double getAzimuth()
      Return the azimuth angle in radians. The value will be in the range [0, 2pi).
      Returns:
      azimuth value in radians.

    • getDimension

      public int getDimension()
      Returns the number of dimensions in the space that this element belongs to.
      Specified by:
      getDimension in interface Spatial
      Returns:
      the number of dimensions in the element's space

    • isNaN

      public boolean isNaN()
      Returns true if any value in this element is NaN; otherwise returns false.
      Specified by:
      isNaN in interface Spatial
      Returns:
      true if any value in this element is NaN

    • isInfinite

      public boolean isInfinite()
      Returns true if any value in this element is infinite and none are NaN; otherwise, returns false.
      Specified by:
      isInfinite in interface Spatial
      Returns:
      true if any value in this element is infinite and none are NaN

    • isFinite

      public boolean isFinite()
      Returns true if all values in this element are finite, meaning they are not NaN or infinite.
      Specified by:
      isFinite in interface Spatial
      Returns:
      true if all values in this element are finite

    • toCartesian

      public Vector2D toCartesian()
      Convert this set of polar coordinates to Cartesian coordinates.
      Returns:
      A 2-dimensional vector with an equivalent set of coordinates in Cartesian form

    • hashCode

      public int hashCode()
      Get a hashCode for this set of polar coordinates.

      All NaN values have the same hash code.

      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this object

    • equals

      public boolean equals(Object other)
      Test for the equality of two sets of polar coordinates.

      If all values of two sets of coordinates are exactly the same, and none are Double.NaN, the two sets are considered to be equal.

      NaN values are considered to globally affect the coordinates and be equal to each other - i.e, if either (or all) values of the coordinate set are equal to Double.NaN, the set as a whole is considered to equal NaN.

      Overrides:
      equals in class Object
      Parameters:
      other - Object to test for equality to this
      Returns:
      true if two PolarCoordinates objects are equal, false if object is null, not an instance of PolarCoordinates, or not equal to this PolarCoordinates instance

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • of

      public static PolarCoordinates of(double radius, double azimuth)
      Return a new instance with the given polar coordinate values. The values are normalized so that radius lies in the range [0, +Infinity) and azimuth in the range [0, 2pi).
      Parameters:
      radius - Radius value.
      azimuth - Azimuth angle in radians.
      Returns:
      new PolarCoordinates instance

    • fromCartesian

      public static PolarCoordinates fromCartesian(double x, double y)
      Convert the given Cartesian coordinates to polar form.
      Parameters:
      x - X coordinate value
      y - Y coordinate value
      Returns:
      polar coordinates equivalent to the given Cartesian coordinates

    • fromCartesian

      public static PolarCoordinates fromCartesian(Vector2D vec)
      Convert the given Cartesian coordinates to polar form.
      Parameters:
      vec - vector containing Cartesian coordinates
      Returns:
      polar coordinates equivalent to the given Cartesian coordinates

    • toCartesian

      public static Vector2D toCartesian(double radius, double azimuth)
      Convert the given polar coordinates to Cartesian form.
      Parameters:
      radius - Radius value.
      azimuth - Azimuth angle in radians.
      Returns:
      A 2-dimensional vector with an equivalent set of coordinates in Cartesian form

    • parse

      public static PolarCoordinates parse(String input)
      Parse the given string and return a new polar coordinates instance. The parsed coordinates are normalized as in the of(double, double) method. The expected string format is the same as that returned by toString().
      Parameters:
      input - the string to parse
      Returns:
      new PolarCoordinates instance
      Throws:
      IllegalArgumentException - if the string format is invalid.

    • normalizeAzimuth

      public static double normalizeAzimuth(double azimuth)
      Normalize an azimuth value to be within the range [0, 2pi).
      Parameters:
      azimuth - azimuth value in radians
      Returns:
      equivalent azimuth value in the range [0, 2pi).