uk.ac.starlink.ttools.plot2.data
Class SkyCoord

java.lang.Object
  uk.ac.starlink.ttools.plot2.data.SkyCoord

All Implemented Interfaces:

Coord

public abstract class SkyCoord
extends Object
implements Coord

Coord implementation for sky positions. To the user these look like (longitude, latitude) pairs, but they are stored as (x,y,z) triples. This class exists in two variants: for surface the vectors are normalised to a magnitude of 1, so that they all fall on the centre of the unit sphere. For volume, that constraint does not apply.

Since:

4 Feb 2013

Author:

Mark Taylor

Nested Class Summary

static class

SkyCoord.SkyVariant Controls the interpretation of sky vectors, either fixed to the surface of the unit sphere or not.

Method Summary

static SkyCoord	createCoord(SkyCoord.SkyVariant variant, boolean isRequired) Factory method to create an instance of this class.
Input[]	getInputs() Returns specifications of the one or more input values the user supplies to provide the data values for this coord.
StorageType	getStorageType() Returns a code indicating how the quantity defined by this object is stored internally and presented to the plotting classes.
boolean	isRequired() Indicates whether this item must have a non-blank value in order for a plot to be possible.
static double[]	lonLatDegreesToDouble3(double lonDeg, double latDeg) Converts a longitude, latitude pair into a normalised 3-vector.
abstract boolean	readSkyCoord(Tuple tuple, int icol, double[] v3) Reads a sky vector value from an appropriate column in the current row of a given Tuple.

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.starlink.ttools.plot2.data.Coord

inputToStorage

Method Detail

getInputs

public Input[] getInputs()

Description copied from interface: Coord

Returns specifications of the one or more input values the user supplies to provide the data values for this coord.

Specified by:

getInputs in interface Coord

Returns:

one or more items describing the user input values for this quantity

getStorageType

public StorageType getStorageType()

Description copied from interface: Coord

Returns a code indicating how the quantity defined by this object is stored internally and presented to the plotting classes.

Specified by:

getStorageType in interface Coord

Returns:

storage type enum instance

isRequired

public boolean isRequired()

Description copied from interface: Coord

Indicates whether this item must have a non-blank value in order for a plot to be possible.

Specified by:

isRequired in interface Coord

Returns:

if true, values must be supplied to make a plot

readSkyCoord

public abstract boolean readSkyCoord(Tuple tuple,
                                     int icol,
                                     double[] v3)

Reads a sky vector value from an appropriate column in the current row of a given Tuple.

Parameters:

tuple - tuple

icol - index of field in tuple corresponding to this Coord

v3 - 3-element vector into which the (x,y,z) sky position will be written

Returns:

true iff a valid position has been successfully read

createCoord

public static SkyCoord createCoord(SkyCoord.SkyVariant variant,
                                   boolean isRequired)

Factory method to create an instance of this class.

Parameters:

variant - type of sky coordinates

isRequired - true if this coordinate is required for plotting

lonLatDegreesToDouble3

public static double[] lonLatDegreesToDouble3(double lonDeg,
                                              double latDeg)

Converts a longitude, latitude pair into a normalised 3-vector. If the input values are out of range, the components of the returned vector will all be NaN.

Parameters:

lonDeg - longitude in degrees

latDeg - latitude in degrees

Returns:

(x,y,z) array of components of a normalised vector