com.google.common.math

Class LinearTransformation

java.lang.Object

com.google.common.math.LinearTransformation

@Beta
 @GwtIncompatible
public abstract class LinearTransformation
extends Object

The representation of a linear transformation between real numbers x and y. Graphically, this is the specification of a straight line on a plane. The transformation can be expressed as y = m * x + c for finite m and c, unless it is a vertical transformation in which case x has a constant value for all y. In the non-vertical case, m is the slope of the transformation (and a horizontal transformation has zero slope).

Since:

20.0

Author:

Pete Gillin

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LinearTransformation.LinearTransformationBuilder This is an intermediate stage in the construction process.

Constructor Summary

Constructors

Constructor and Description
LinearTransformation()

Method Summary

Modifier and Type	Method and Description
static LinearTransformation	forNaN() Builds an instance for datasets which contains Double.NaN.
static LinearTransformation	horizontal(double y) Builds an instance representing a horizontal transformation with a constant value of y.
abstract LinearTransformation	inverse() Returns the inverse linear transformation.
abstract boolean	isHorizontal() Returns whether this is a horizontal transformation.
abstract boolean	isVertical() Returns whether this is a vertical transformation.
static LinearTransformation.LinearTransformationBuilder	mapping(double x1, double y1) Start building an instance which maps x = x1 to y = y1.
abstract double	slope() Returns the slope of the transformation, i.e.
abstract double	transform(double x) Returns the y corresponding to the given x.
static LinearTransformation	vertical(double x) Builds an instance representing a vertical transformation with a constant value of x.

Methods inherited from class java.lang.Object

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

Constructor Detail

LinearTransformation

public LinearTransformation()

Method Detail

mapping

public static LinearTransformation.LinearTransformationBuilder mapping(double x1,
                                                                       double y1)

Start building an instance which maps x = x1 to y = y1. Both arguments must be finite. Call either LinearTransformation.LinearTransformationBuilder.and(double, double) or LinearTransformation.LinearTransformationBuilder.withSlope(double) on the returned object to finish building the instance.

vertical

public static LinearTransformation vertical(double x)

Builds an instance representing a vertical transformation with a constant value of x. (The inverse of this will be a horizontal transformation.)

horizontal

public static LinearTransformation horizontal(double y)

Builds an instance representing a horizontal transformation with a constant value of y. (The inverse of this will be a vertical transformation.)

forNaN

public static LinearTransformation forNaN()

Builds an instance for datasets which contains Double.NaN. The isHorizontal() and isVertical() methods return false and the slope(), and transform(double) methods all return Double.NaN. The inverse() method returns the same instance.

isVertical

public abstract boolean isVertical()

Returns whether this is a vertical transformation.

isHorizontal

public abstract boolean isHorizontal()

Returns whether this is a horizontal transformation.

slope

public abstract double slope()

Returns the slope of the transformation, i.e. the rate of change of y with respect to x. This must not be called on a vertical transformation (i.e. when isVertical() is true).

transform

public abstract double transform(double x)

Returns the y corresponding to the given x. This must not be called on a vertical transformation (i.e. when isVertical() is true).

inverse

public abstract LinearTransformation inverse()

Returns the inverse linear transformation. The inverse of a horizontal transformation is a vertical transformation, and vice versa. The inverse of the forNaN() transformation is itself. In all other cases, the inverse is a transformation such that applying both the original transformation and its inverse to a value gives you the original value give-or-take numerical errors. Calling this method multiple times on the same instance will always return the same instance. Calling this method on the result of calling this method on an instance will always return that original instance.