Class JoinStarTable

java.lang.Object
uk.ac.starlink.table.AbstractStarTable
uk.ac.starlink.table.JoinStarTable
All Implemented Interfaces:
Closeable, AutoCloseable, StarTable

public class JoinStarTable extends AbstractStarTable
Joins a number of tables to produce a single combined table. The result consists of all the constituent tables side by side, so has a number of columns equal to the sum of the numbers of columns in all the constituent tables. The nth row of this table is composed by appending the nth rows of all the constituent tables together in sequence. The number of rows is equal to the smallest of all the number of rows in the constituent tables (typically they will all have the same number of rows). Random access is only available if it is available in all the constituent tables.

While this table is active, the columns that the constituent tables had at the time of its construction shouldn't change their characteristics in incompatible ways or disappear. It's OK to add new columns though.

Author:
Mark Taylor (Starlink)
  • Constructor Details

    • JoinStarTable

      public JoinStarTable(StarTable[] tables, JoinFixAction[] fixCols)
      Constructs a new JoinStarTable from a list of constituent tables, optionally renaming duplicated column names.
      Parameters:
      tables - array of constituent table objects providing the data and metadata for a new joined table
      fixCols - actions to be taken in modifying column names from the originals (may be null for no action)
    • JoinStarTable

      public JoinStarTable(StarTable[] tables)
      Constructs a new JoinStarTable from a list of constituent tables. No column renaming is done.
      Parameters:
      tables - array of constituent table objects providing the data and metadata for a new joined table
  • Method Details

    • getTables

      public List<StarTable> getTables()
      Returns an unmodifiable list of the constituent tables providing the base data for this join table.
      Returns:
      list of tables
    • getColumnCount

      public int getColumnCount()
      Description copied from interface: StarTable
      Returns the number of columns in this table.
      Specified by:
      getColumnCount in interface StarTable
      Specified by:
      getColumnCount in class AbstractStarTable
      Returns:
      the number of columns
    • 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
      Specified by:
      getRowCount in class AbstractStarTable
      Returns:
      the number of rows, or -1
    • getColumnInfo

      public ColumnInfo getColumnInfo(int icol)
      Description copied from interface: StarTable
      Returns the object describing the data in a given column.
      Specified by:
      getColumnInfo in interface StarTable
      Specified by:
      getColumnInfo in class AbstractStarTable
      Parameters:
      icol - the column for which header information is required
      Returns:
      a ValueInfo object for column icol
    • isRandom

      public boolean isRandom()
      Description copied from class: AbstractStarTable
      The AbstractStarTable implementation of this method returns false.
      Specified by:
      isRandom in interface StarTable
      Overrides:
      isRandom in class AbstractStarTable
      Returns:
      true if table random access methods are available
    • getCell

      public Object getCell(long irow, int icol) throws IOException
      Description copied from class: AbstractStarTable
      The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.
      Specified by:
      getCell in interface StarTable
      Overrides:
      getCell in class AbstractStarTable
      Parameters:
      irow - the index of the cell's row
      icol - the index of the cell's column
      Returns:
      the contents of this cell
      Throws:
      IOException - if there is an error reading the data
    • getRow

      public Object[] getRow(long irow) throws IOException
      Description copied from class: AbstractStarTable
      The AbstractStarTable implementation of this method constructs a row by repeated invocation of AbstractStarTable.getCell(long, int).
      Specified by:
      getRow in interface StarTable
      Overrides:
      getRow in class AbstractStarTable
      Parameters:
      irow - the index of the row to retrieve
      Returns:
      an array of the objects in each cell in row irow
      Throws:
      IOException - if there is an error reading the data
    • getRowSequence

      public RowSequence getRowSequence() throws IOException
      Description copied from interface: StarTable
      Returns an object which can iterate over all the rows in the table sequentially. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.
      Specified by:
      getRowSequence in interface StarTable
      Specified by:
      getRowSequence in class AbstractStarTable
      Returns:
      new RowSequence
      Throws:
      IOException - if there is an error providing access
    • getRowAccess

      public RowAccess getRowAccess() throws IOException
      Description copied from interface: StarTable
      Returns an object which can provide random access to this table's data, if random access is implemented. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.
      Specified by:
      getRowAccess in interface StarTable
      Overrides:
      getRowAccess in class AbstractStarTable
      Returns:
      new RowAccess
      Throws:
      IOException - if there is an error setting up access
    • close

      public void close() throws IOException
      Closes all the constituent tables.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface StarTable
      Overrides:
      close in class AbstractStarTable
      Throws:
      IOException