Package uk.ac.starlink.ttools.plot2.geom

Class HealpixDataGeom

  • All Implemented Interfaces:
    DataGeom
    public abstract class HealpixDataGeom
extends java.lang.Object
implements DataGeom
    DataGeom implementation for HEALPix indices. This can convert from a single integer to a sky position, the center of the corresponding HEALPix cell. It has to be parameterised by the HEALPix level, and optionally data/view sky system information.

    In general you should use the provided factory methods to instantiate this abstract class. If you want to implement a concrete subclass, make sure you implement the methods requred Equality.

    Since:
    21 Dec 2018
    Author:
    Mark Taylor

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static HealpixDataGeom createGeom​(int level, boolean isNest, SkySys userSys, SkySys viewSys)
      Creates a data geom with input user data in one sky system and output data coordinates in another sky system.
      boolean equals​(java.lang.Object o)  
      int getDataDimCount()
      Returns 3.
      Coord[] getPosCoords()
      Returns the definitions for the user-supplied coordinates that indicate plot positions.
      java.lang.String getVariantName()
      Returns a label for this DataGeom.
      int hashCode()  
      boolean hasPosition()
      Indicates whether the values read by the readDataPos method correspond to a point position in the data space.
      boolean readDataPos​(Tuple tuple, int icol, double[] dpos)
      Determines the positional coordinates in data space for a supplied tuple.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • HEALPIX_COORD

        public static final LongCoord HEALPIX_COORD
        Coordinate for HEALPix pixel index.

      • DUMMY_INSTANCE

        public static final HealpixDataGeom DUMMY_INSTANCE
        Placeholder instance. This can be used where an instance of this class is required for documentation purposes, but it is not capable of actual transformations.

    • Method Detail

      • getDataDimCount

        public int getDataDimCount()
        Returns 3.
        Specified by:
        getDataDimCount in interface DataGeom
        Returns:
        number of elements in data space coordinate array

      • hasPosition

        public boolean hasPosition()
        Description copied from interface: DataGeom
        Indicates whether the values read by the readDataPos method correspond to a point position in the data space. If true, a successful read will result in a position array with a definite value for each coordinate. If false, some of the coordinates may be NaN. A false return value would be appropriate for instance if each tuple row for the plot layer represented by this geom corresponds to a line rather than a point in the data space.
        Specified by:
        hasPosition in interface DataGeom
        Returns:
        true iff this geom represents point positions

      • getVariantName

        public java.lang.String getVariantName()
        Description copied from interface: DataGeom
        Returns a label for this DataGeom. It may be used to distinguish from other geoms used in the same plot type, so for instance call it "Cartesian" or "Polar" rather than "Plane" if it's X,Y.
        Specified by:
        getVariantName in interface DataGeom
        Returns:
        user-directed input coordinate type name

      • getPosCoords

        public Coord[] getPosCoords()
        Description copied from interface: DataGeom
        Returns the definitions for the user-supplied coordinates that indicate plot positions.
        Specified by:
        getPosCoords in interface DataGeom
        Returns:
        coordinate quantity array for this geometry

      • readDataPos

        public boolean readDataPos​(Tuple tuple,
                           int icol,
                           double[] dpos)
        Description copied from interface: DataGeom
        Determines the positional coordinates in data space for a supplied tuple.

        A parameter supplies the index of the field in the tuple at which the positional coordinate(s) can be found. Each position is represented by DataGeom.getPosCoords() columns of the tuple. By convention positions are at the start of the tuple, so if there is one position in the tuple it will be at icol=0, and there are multiple positions the N'th one will be at icol=N*getPosCoords().

        An array of (at least) DataGeom.getDataDimCount() elements is supplied, and on success the data space coordinate values are written into it.

        Specified by:
        readDataPos in interface DataGeom
        Parameters:
        tuple - coordinate tuple
        icol - column index in tuple at which the positional information starts
        dpos - array into which data space coordinates are written
        Returns:
        true iff conversion was successful

      • equals

        public boolean equals​(java.lang.Object o)
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • createGeom

        public static HealpixDataGeom createGeom​(int level,
                                         boolean isNest,
                                         SkySys userSys,
                                         SkySys viewSys)
        Creates a data geom with input user data in one sky system and output data coordinates in another sky system. If both of the supplied sky systems are supplied, the corresponding rotation will be applied; if one or zero are supplied, these parameters are ignored.
        Parameters:
        level - healpix level (log2(nside))
        userSys - sky system in which user data is supplied, may be null
        viewSys - sky system in which the plot is viewed, may be null
        Returns:
        new data geom