uk.ac.starlink.ttools.plot2

Class Scalings

java.lang.Object

uk.ac.starlink.ttools.plot2.Scalings

public class Scalings
extends Object

Implementation class for functions to do with Scaling instances.

Since:

21 Mar 2019

Author:

Mark Taylor

Method Summary

Modifier and Type	Method and Description
static boolean	canScale(Scaling[] scalings, Span dataSpan, Span fixSpan) Determines whether all of a list of scalings can be used to create Scaler objects from given span instances.
static Scaling.RangeScaling	createAutoScaling(String name, double delta) Constructs a scaling suitable for automatic density distributions.
static Ranger	createRanger(Scaling[] scalings) Returns a ranger suitable for use with all of a given list of scalings.
static double	unscale(Scaler scaler, double lo, double hi, double frac) Utility method to perform the inverse operation of Scaler.scaleValue.

Methods inherited from class java.lang.Object

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

Method Detail

createRanger

public static Ranger createRanger(Scaling[] scalings)

Returns a ranger suitable for use with all of a given list of scalings. If a ranger is obtained from this method and used to create a Span, that span's createScaler method can be used with any of the scalings presented here.

Parameters:

scalings - list of scalings required for compatibility; null values are permitted, and add no constraints

Returns:

suitable ranger

canScale

public static boolean canScale(Scaling[] scalings,
                               Span dataSpan,
                               Span fixSpan)

Determines whether all of a list of scalings can be used to create Scaler objects from given span instances.

Parameters:

scalings - scaling instances for which scalers may be required

dataSpan - span obtained from ranging data

fixSpan - span obtained by direct user input of bounds

Returns:

true iff spans are sufficient, false if new span instances are going to be needed

createAutoScaling

public static Scaling.RangeScaling createAutoScaling(String name,
                                                     double delta)

Constructs a scaling suitable for automatic density distributions.

Parameters:

name - scaling name

delta - output difference for lower-end input unit difference

Returns:

scaling

unscale

public static double unscale(Scaler scaler,
                             double lo,
                             double hi,
                             double frac)

Utility method to perform the inverse operation of Scaler.scaleValue.

Parameters:

scaler - scaler instance

lo - lower bound of input data value

hi - upper bound of input data value

frac - required output value of scaleValue method, must be in range 0..1

Returns:

value x that causes scaler.scaleValue(x) to return frac