uk.ac.starlink.ttools.plot2

Interface Scale

@Equality
public interface Scale

Represents a mapping of data values to some linear scale. The function is assumed to be strictly monotonic increasing and continuous.

All finite values are permitted for both the data and the scale, except as documented by the isPositiveDefinite() method.

The LINEAR and LOG instances are provided as static members of this class; to produce other instances, see the ScaleType class.

Since:

12 Mar 2025

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static Scale	LINEAR
static Scale	LOG
static Scale	TIME

Method Summary

Modifier and Type	Method and Description
double	dataToScale(double d) Forward mapping.
String	dataToScaleExpression(String var) Returns an algebraic expression representing the mapping of a variable from data space to scale space.
double[]	getParamValues() Returns the array of parameter values that combined with the scale type fully specify this scale.
Rounder	getScaleRounder() Returns an object which can round scale values to a value that counts as a round number.
ScaleType	getScaleType() Returns the type of this scale.
Ticker	getTicker() Returns an object that can generate axis ticks for this scale.
boolean	isLinear() Indicates whether the scaling relation is linear.
boolean	isPositiveDefinite() If this method returns true, then only data values that are strictly greater than zero can be mapped to the scale, and a data value of zero is mapped to a scale value of negative infinity.
double	scaleToData(double s) Inverse mapping.

Field Detail

LINEAR

static final Scale LINEAR

LOG

static final Scale LOG

TIME

static final Scale TIME

Method Detail

getScaleType

ScaleType getScaleType()

Returns the type of this scale.

Returns:

scale type

getParamValues

double[] getParamValues()

Returns the array of parameter values that combined with the scale type fully specify this scale.

Returns:

scale parameter values, same length as getScaleType().getParams()

dataToScale

double dataToScale(double d)

Forward mapping.

Parameters:

d - data value

Returns:

scale value

scaleToData

double scaleToData(double s)

Inverse mapping.

Parameters:

s - scale value

Returns:

data value

isPositiveDefinite

boolean isPositiveDefinite()

If this method returns true, then only data values that are strictly greater than zero can be mapped to the scale, and a data value of zero is mapped to a scale value of negative infinity. Otherwise, any finite data value and any finite scale value can be mapped to a finite value in the other domain.

Returns:

true iff negative data values are excluded

isLinear

boolean isLinear()

Indicates whether the scaling relation is linear.

Returns:

true for uniformly linear scaling, false otherwise

getTicker

Ticker getTicker()

Returns an object that can generate axis ticks for this scale.

Returns:

ticker

getScaleRounder

Rounder getScaleRounder()

Returns an object which can round scale values to a value that counts as a round number.

Returns:

rounder for the scale quantity

dataToScaleExpression

String dataToScaleExpression(String var)

Returns an algebraic expression representing the mapping of a variable from data space to scale space.

Parameters:

var - input variable representation