uk.ac.starlink.ast

Class SelectorMap

java.lang.Object

uk.ac.starlink.ast.AstObject

uk.ac.starlink.ast.Mapping

uk.ac.starlink.ast.SelectorMap

public class SelectorMap
extends Mapping

Java interface to the AST SelectorMap class - a Mapping that locates positions within one of a set of alternate Regions. A SelectorMap is a Mapping that identifies which Region contains a given input position.

A SelectorMap encapsulates a number of Regions that all have the same number of axes and represent the same coordinate Frame. The number of inputs (Nin attribute) of the SelectorMap equals the number of axes spanned by one of the encapsulated Region. All SelectorMaps have only a single output. SelectorMaps do not define an inverse transformation.

For each input position, the forward transformation of a SelectorMap searches through the encapsulated Regions (in the order supplied when the SelectorMap was created) until a Region is found which contains the input position. The index associated with this Region is returned as the SelectorMap output value (the index value is the position of the Region within the list of Regions supplied when the SelectorMap was created, starting at 1 for the first Region). If an input position is not contained within any Region, a value of zero is returned by the forward transformation.

If a compound Mapping contains a SelectorMap in series with its own inverse, the combination of the two adjacent SelectorMaps will be replaced by a UnitMap when the compound Mapping is simplified using astSimplify.

In practice, SelectorMaps are often used in conjunction with SwitchMaps.

Licence

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public Licence as published by the Free Software Foundation; either version 2 of the Licence, or (at your option) any later version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public Licence for more details.

You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA

See Also:

AST SelectorMap

Nested Class Summary

Nested classes/interfaces inherited from class uk.ac.starlink.ast.Mapping

Mapping.Interpolator, Mapping.Spreader

Field Summary

Fields inherited from class uk.ac.starlink.ast.Mapping

LINEAR_INTERPOLATOR, LINEAR_SPREADER, NEAREST_INTERPOLATOR, NEAREST_SPREADER

Fields inherited from class uk.ac.starlink.ast.AstObject

AST__BAD, AST__TUNULL, pointer

Constructor Summary

Constructors

Constructor and Description
SelectorMap(Region[] regs, double badval) Creates a SelectorMap.

Method Summary

Methods inherited from class uk.ac.starlink.ast.Mapping

decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP

Methods inherited from class uk.ac.starlink.ast.AstObject

annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SelectorMap

public SelectorMap(Region[] regs,
                   double badval)

Creates a SelectorMap.

Parameters:

regs - An array of pointers to the Regions. All the supplied Regions must relate to the same coordinate Frame. The number of axes in this coordinate Frame defines the number of inputs for the SelectorMap.

badval - The value to be returned by the forward transformation of the SelectorMap for any input positions that have a bad (AST__BAD) value on any axis.

Throws:

AstException - if an error occurred in the AST library