uk.ac.starlink.table
Class RowPermutedStarTable

java.lang.Object
  extended by uk.ac.starlink.table.WrapperStarTable
      extended by uk.ac.starlink.table.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.


Field Summary
 
Fields inherited from class uk.ac.starlink.table.WrapperStarTable
baseTable
 
Constructor Summary
RowPermutedStarTable(StarTable baseTable)
          Constructs a new RowPermutedTable with rows initially in unpermuted order.
RowPermutedStarTable(StarTable baseTable, long[] rowMap)
          Constructs a new RowPermutedStarTable from a base table and a rowMap array.
 
Method Summary
 java.lang.Object getCell(long irow, int icol)
          Returns the contents of a given table cell.
 java.lang.Object[] getRow(long irow)
          Returns the contents of a given table row.
 long getRowCount()
          Returns the number of rows in this table, if known.
 long[] getRowMap()
          Returns the mapping array.
 RowSequence getRowSequence()
          Returns an object which can iterate over all the rows in the table sequentially.
 boolean isRandom()
          Returns true.
 void setRowMap(long[] rowMap)
          Sets the mapping array.
 
Methods inherited from class uk.ac.starlink.table.WrapperStarTable
checkedLongToInt, getBaseTable, getColumnAuxDataInfos, getColumnCount, getColumnInfo, getName, getParameterByName, getParameters, getURL, setName, setParameter, setURL, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

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

getRowSequence

public RowSequence getRowSequence()
Description copied from interface: StarTable
Returns an object which can iterate over all the rows in the table sequentially.

Specified by:
getRowSequence in interface StarTable
Overrides:
getRowSequence in class WrapperStarTable
Returns:
an object providing sequential access to the table data

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