uk.ac.starlink.ast
Class PointList

java.lang.Object
  extended by uk.ac.starlink.ast.AstObject
      extended by uk.ac.starlink.ast.Mapping
          extended by uk.ac.starlink.ast.Frame
              extended by uk.ac.starlink.ast.Region
                  extended by uk.ac.starlink.ast.PointList

public class PointList
extends Region

Java interface to the AST PointList class - a collection of points in a Frame. The PointList class implements a Region which represents a collection of points in a Frame.

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 PointList

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.Region
OVERLAP_INSIDE, OVERLAP_NEGATE, OVERLAP_NONE, OVERLAP_OUTSIDE, OVERLAP_PARTIAL, OVERLAP_SAME, OVERLAP_UNKNOWN
 
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
PointList(Frame frame, int npnt, double[][] points, Region unc)
          Create a PointList.
 
Method Summary
 int getListSize()
          Get number of points in a PointList.
 
Methods inherited from class uk.ac.starlink.ast.Region
getAdaptive, getBounded, getClosed, getFillFactor, getMeshSize, getNegated, getRegionBounds, getRegionFrame, getRegionPoints, getUnc, mapRegion, mask, maskB, maskD, maskF, maskI, maskL, maskS, negate, overlap, setAdaptive, setClosed, setFillFactor, setMeshSize, setNegated, setUnc, showMesh
 
Methods inherited from class uk.ac.starlink.ast.Frame
angle, axAngle, axDistance, axOffset, convert, distance, findFrame, format, getActiveUnit, getAlignSystem, getBottom, getDigits, getDigits, getDirection, getDomain, getDut1, getEpoch, getFormat, getLabel, getMatchEnd, getMaxAxes, getMinAxes, getNaxes, getNormUnit, getObsLat, getObsLon, getPermute, getPreserveAxes, getSymbol, getSystem, getTitle, getTop, getUnit, intersect, norm, offset, offset2, permAxes, pickAxes, resolve, setActiveUnit, setAlignSystem, setBottom, setDigits, setDigits, setDirection, setDomain, setDut1, setEpoch, setEpoch, setFormat, setLabel, setMatchEnd, setMaxAxes, setMinAxes, setObsLat, setObsLon, setPermute, setPreserveAxes, setSymbol, setSystem, setTitle, setTop, setUnit, unformat
 
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

PointList

public PointList(Frame frame,
                 int npnt,
                 double[][] points,
                 Region unc)
Create a PointList. This function creates a new PointList object and optionally initialises its attributes.

A PointList object is a specialised type of Region which represents a collection of points in a coordinate Frame.

Notes


- A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Status Handling

The protected interface to this function includes an extra parameter at the end of the parameter list descirbed above. This parameter is a pointer to the integer inherited status variable: "int *status".

Parameters:
frame - A pointer to the Frame in which the region is defined. A deep copy is taken of the supplied Frame. This means that any subsequent changes made to the Frame using the supplied pointer will have no effect the Region.
npnt - The number of points in the Region.
points - An array giving the coordinates in frame of the points. points is an naxes-element array of npnt-element double arrays, where naxes is the number of axes in frame. The value of coordinate number icoord for point number ipoint is therefore stored at points[icoord][ipoint].
unc - An optional pointer to an existing Region which specifies the uncertainties associated with each point in the PointList being created. The uncertainty at any point in the PointList is found by shifting the supplied "uncertainty" Region so that it is centred at the point being considered. The area covered by the shifted uncertainty Region then represents the uncertainty in the position. The uncertainty is assumed to be the same for all points.

If supplied, the uncertainty Region must be of a class for which all instances are centro-symetric (e.g. Box, Circle, Ellipse, etc.) or be a Prism containing centro-symetric component Regions. A deep copy of the supplied Region will be taken, so subsequent changes to the uncertainty Region using the supplied pointer will have no effect on the created Box. Alternatively, a NULL Object pointer may be supplied, in which case a default uncertainty is used equivalent to a box 1.0E-6 of the size of the bounding box of the PointList being created.

The uncertainty Region has two uses: 1) when the astOverlap function compares two Regions for equality the uncertainty Region is used to determine the tolerance on the comparison, and 2) when a Region is mapped into a different coordinate system and subsequently simplified (using astSimplify), the uncertainties are used to determine if the transformed boundary can be accurately represented by a specific shape of Region.

Throws:
AstException - if an error occurred in the AST library
Method Detail

getListSize

public int getListSize()
Get number of points in a PointList. This is a read-only attribute giving the number of points in a PointList. This value is determined when the PointList is created.

Returns:
this object's ListSize attribute


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