Class RowPermutedStarTable

  • All Implemented Interfaces:
    StarTable

    public class RowPermutedStarTable
    extends WrapperStarTable
    Wrapper table which provides a view of a base table in which the rows are permuted. Each row in the wrapper table is a view of one in the base table. It is permitted for the wrapper to contain multiple views of the same column in the base.

    A long[] array, rowMap, is used to keep track of which rows in this table correspond to which rows in the base table; the n'th row in this table corresponds to the rowMap[n]'th row in the base table. The rowMap array may contain duplicate entries, but should not contain any entries larger than the number of rows in the base table. Any negative entry is treated as a special case resulting in a 'blank' row of all null values. It can be modified during the life of the table, but it's not a good idea to do this while a RowSequence is active.

    Author:
    Mark Taylor (Starlink)
    • Constructor Detail

      • RowPermutedStarTable

        public RowPermutedStarTable​(StarTable baseTable,
                                    long[] rowMap)
        Constructs a new RowPermutedStarTable from a base table and a rowMap array.

        baseTable must provide random access.

        Parameters:
        baseTable - base table
        rowMap - array mapping rows in the new permuted table to rows in baseTable
        Throws:
        java.lang.IllegalArgumentException - if baseTable.isRandom returns false
      • RowPermutedStarTable

        public RowPermutedStarTable​(StarTable baseTable)
        Constructs a new RowPermutedTable with rows initially in unpermuted order.
        Parameters:
        baseTable - base table
    • Method Detail

      • getRowMap

        public long[] getRowMap()
        Returns the mapping array.
        Returns:
        array mapping rows in this table to rows in the base table
      • setRowMap

        public void setRowMap​(long[] rowMap)
        Sets the mapping array.
        Parameters:
        rowMap - array mapping rows in this table to rows in the base table
      • getRowCount

        public long getRowCount()
        Description copied from interface: StarTable
        Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.
        Specified by:
        getRowCount in interface StarTable
        Overrides:
        getRowCount in class WrapperStarTable
        Returns:
        the number of rows, or -1
      • isRandom

        public boolean isRandom()
        Returns true.
        Specified by:
        isRandom in interface StarTable
        Overrides:
        isRandom in class WrapperStarTable
        Returns:
        true if table random access methods are available
      • getCell

        public java.lang.Object getCell​(long irow,
                                        int icol)
                                 throws java.io.IOException
        Description copied from interface: StarTable
        Returns the contents of a given table cell. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass().
        Specified by:
        getCell in interface StarTable
        Overrides:
        getCell in class WrapperStarTable
        Parameters:
        irow - the index of the cell's row
        icol - the index of the cell's column
        Returns:
        the contents of this cell
        Throws:
        java.io.IOException - if there is an error reading the data
      • getRow

        public java.lang.Object[] getRow​(long irow)
                                  throws java.io.IOException
        Description copied from interface: StarTable
        Returns the contents of a given table row. The returned value is equivalent to an array formed of all the objects returned by getCell(irow,icol) for all the columns icol in sequence.
        Specified by:
        getRow in interface StarTable
        Overrides:
        getRow in class WrapperStarTable
        Parameters:
        irow - the index of the row to retrieve
        Returns:
        an array of the objects in each cell in row irow
        Throws:
        java.io.IOException - if there is an error reading the data