Package uk.ac.starlink.fits

Class StandardFitsTableSerializer

  • All Implemented Interfaces:
    FitsTableSerializer
    Direct Known Subclasses:
    VariableFitsTableSerializer
    public class StandardFitsTableSerializer
extends java.lang.Object
implements FitsTableSerializer
    Class which knows how to do the various bits of serializing a StarTable to FITS BINTABLE format. A normal (row-oriented) organisation of the data is used. Array-valued columns are all written as fixed size arrays. This class does the hard work for FitsTableWriter.

    When writing tables that are marked up using the headers defined in HealpixTableInfo, this serializer will attempt to insert FITS headers corresponding to the HEALPix-FITS convention.

    Author:
    Mark Taylor (Starlink)
    See Also:
    HEALPix-FITS convention

    • Constructor Summary

      Constructors 
      Constructor Description
      StandardFitsTableSerializer​(uk.ac.starlink.table.StarTable table, boolean allowSignedByte, WideFits wide)
      Constructs a serializer to write a given StarTable, with explicit instruction about how to write byte-type columns data.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.String getBadValue​(int icol)
      Returns the bad value (text of the TNULLnn card), if any, used for a given column.
      int[] getDimensions​(int icol)
      Returns the dimensions of the items which will be output for a given column.
      char getFormatChar​(int icol)
      Returns the FITS TFORM letter which describes the type of data output for a given column.
      nom.tam.fits.Header getHeader()
      Returns a header suitable for the HDU which will contain the table.
      protected nom.tam.fits.HeaderCard[] getHealpixHeaders​(uk.ac.starlink.table.HealpixTableInfo hpxInfo)
      Returns FITS headers specific for a table containing a HEALPix map.
      long getRowCount()
      Returns the number of rows which will be output.
      void writeData​(java.io.DataOutput strm)
      Writes the HDU data for the table to an output stream.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • StandardFitsTableSerializer

        public StandardFitsTableSerializer​(uk.ac.starlink.table.StarTable table,
                                   boolean allowSignedByte,
                                   WideFits wide)
                            throws java.io.IOException
        Constructs a serializer to write a given StarTable, with explicit instruction about how to write byte-type columns data. Since FITS bytes are unsigned (unlike, for instance, java bytes), they can cause trouble in some circumstances, so avoiding writing them may sometimes help.
        Parameters:
        table - the table to be written
        allowSignedByte - if true, bytes written as FITS signed bytes (TZERO=-128), if false bytes written as signed shorts
        wide - convention for representing over-wide tables; null to avoid this convention
        Throws:
        java.io.IOException - if it won't be possible to write the given table

    • Method Detail

      • getHeader

        public nom.tam.fits.Header getHeader()
                              throws nom.tam.fits.HeaderCardException
        Description copied from interface: FitsTableSerializer
        Returns a header suitable for the HDU which will contain the table.
        Specified by:
        getHeader in interface FitsTableSerializer
        Returns:
        header object
        Throws:
        nom.tam.fits.HeaderCardException

      • writeData

        public void writeData​(java.io.DataOutput strm)
               throws java.io.IOException
        Description copied from interface: FitsTableSerializer
        Writes the HDU data for the table to an output stream.
        Specified by:
        writeData in interface FitsTableSerializer
        Parameters:
        strm - destination stream
        Throws:
        java.io.IOException

      • getFormatChar

        public char getFormatChar​(int icol)
        Description copied from interface: FitsTableSerializer
        Returns the FITS TFORM letter which describes the type of data output for a given column. This is as described by the FITS standard - 'J' for 4-byte integer, 'A' for characters, etc. If the column is not being output, (char)0 will be returned.
        Specified by:
        getFormatChar in interface FitsTableSerializer
        Parameters:
        icol - column to query
        Returns:
        format letter for data in column icol, or 0 for a column being skipped

      • getDimensions

        public int[] getDimensions​(int icol)
        Description copied from interface: FitsTableSerializer
        Returns the dimensions of the items which will be output for a given column. This will be null only if that column is not being output. Otherwise it will be a zero-element array for a scalar, 1-element array for a vector, etc.
        Specified by:
        getDimensions in interface FitsTableSerializer
        Parameters:
        icol - column to query
        Returns:
        dimensions array for data in column icol or null for a column being skipped

      • getBadValue

        public java.lang.String getBadValue​(int icol)
        Description copied from interface: FitsTableSerializer
        Returns the bad value (text of the TNULLnn card), if any, used for a given column.
        Specified by:
        getBadValue in interface FitsTableSerializer
        Parameters:
        icol - column to query
        Returns:
        blank value string, or null if there is none or the column is being skipped

      • getHealpixHeaders

        protected nom.tam.fits.HeaderCard[] getHealpixHeaders​(uk.ac.starlink.table.HealpixTableInfo hpxInfo)
                                               throws uk.ac.starlink.table.TableFormatException,
                                                      nom.tam.fits.HeaderCardException
        Returns FITS headers specific for a table containing a HEALPix map. If this method is called the assumption is that the table looks like it should be a HEALPix map of some sort. If there are problems with the metadata that prevent a consistent set of headers from being generated, a TableFormatException with an informative message should be thrown.
        Parameters:
        hpxInfo - non-null healpix description
        Returns:
        array of FITS headers describing healpix information
        Throws:
        uk.ac.starlink.table.TableFormatException - if HEALPix headers could not be generated
        nom.tam.fits.HeaderCardException