uk.ac.starlink.table

Class ConcatStarTable

java.lang.Object

uk.ac.starlink.table.WrapperStarTable

uk.ac.starlink.table.ConcatStarTable

All Implemented Interfaces:

Closeable, AutoCloseable, StarTable

public class ConcatStarTable
extends WrapperStarTable

StarTable implementation which concatenates several tables together top-to-bottom. A (possibly blank) metadata table is supplied to define the column and table metadata for the result, and other data tables are added on one way or another, depending which constructor is used. The columns of each data table must be compatible with the columns of the metadata table, or the the data will not be included.

Since:

29 Mar 2004

Author:

Mark Taylor

Field Summary

Fields inherited from class uk.ac.starlink.table.WrapperStarTable

baseTable

Constructor Summary

Constructors

Constructor and Description
ConcatStarTable(StarTable meta, Iterator<StarTable> tableIt) Constructs a concatenated table from a metadata table and an iterator over data-bearing tables.
ConcatStarTable(StarTable meta, StarTable[] tables) Constructs a concatenated table from a metadata table and an array of data-bearing tables.

Method Summary

Modifier and Type	Method and Description
static ColumnInfo[]	extendColumnTypes(ColumnInfo[] colInfos, StarTable[] tables) Assembles column metadata objects which are compatible between multiple tables.
Object	getCell(long irow, int icol) Returns the contents of a given table cell.
Object[]	getRow(long irow) Returns the contents of a given table row.
RowAccess	getRowAccess() Returns an object which can provide random access to this table's data, if random access is implemented.
long	getRowCount() Returns the number of rows in this table, if known.
RowSequence	getRowSequence() Returns an object which can iterate over all the rows in the table sequentially.
RowSplittable	getRowSplittable() Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.
boolean	isRandom() Indicates whether random access is provided by this table.

Methods inherited from class uk.ac.starlink.table.WrapperStarTable

checkedLongToInt, close, 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

ConcatStarTable

public ConcatStarTable(StarTable meta,
                       Iterator<StarTable> tableIt)

Constructs a concatenated table from a metadata table and an iterator over data-bearing tables. If any of the tables supplied by the iterator are incompatible with the metadata in meta a warning message is issued through the logging system and its rows are ignored.

Parameters:

meta - table supplying column and table metadata for this one; its row count is ignored and its data is never read

tableIt - iterator over constituent StarTables which taken in sequence supply the row data for this one

ConcatStarTable

public ConcatStarTable(StarTable meta,
                       StarTable[] tables)
                throws IOException

Constructs a concatenated table from a metadata table and an array of data-bearing tables. If any of tables are incompatible with the metadata in meta an IOException is thrown.

Parameters:

meta - table supplying column and table metadata for this one; its row count is ignored and its data is never read

tables - array of tables which taken in sequence supply the row data for this one

Throws:

IOException - if any of tables are not compatible with meta

Method Detail

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

getCell

public Object getCell(long irow,
                      int icol)
               throws 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().

This method is safe for concurrent use from multiple threads, but in general it is recommended to use a RowAccess instead.

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:

IOException - if there is an error reading the data

getRow

public Object[] getRow(long irow)
                throws 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.

This method is safe for concurrent use from multiple threads, but in general it is recommended to use a RowAccess instead.

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:

IOException - if there is an error reading the data

isRandom

public boolean isRandom()

Description copied from interface: StarTable

Indicates whether random access is provided by this table. Only if the result is true may the StarTable.getRowAccess(), StarTable.getRow(long) and StarTable.getCell(long, int) methods be used.

Specified by:

isRandom in interface StarTable

Overrides:

isRandom in class WrapperStarTable

Returns:

true if table random access methods are available

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

Overrides:

getRowSequence in class WrapperStarTable

Returns:

new RowSequence

Throws:

IOException - if there is an error providing access

getRowSplittable

public RowSplittable getRowSplittable()
                               throws IOException

Description copied from interface: StarTable

Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.

The return value must be non-null, and may provide splitting arrangements specially appropriate for the implementation. If this table 'wraps' an upstream table, it is usually best to base the implementation on calls to the the upstream getRowSplittable method, so that upstream policy about how to divide up the table is respected. However, implementations without special requirements may return Tables.getDefaultRowSplittable(this).

Specified by:

getRowSplittable in interface StarTable

Overrides:

getRowSplittable in class WrapperStarTable

Returns:

new RowSplittable

Throws:

IOException

See Also:

RowRunner

getRowAccess

public RowAccess getRowAccess()

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 WrapperStarTable

Returns:

new RowAccess

extendColumnTypes

public static ColumnInfo[] extendColumnTypes(ColumnInfo[] colInfos,
                                             StarTable[] tables)
                                      throws IOException

Assembles column metadata objects which are compatible between multiple tables. Nullability, array shape and element size are set to values which can accommodate all of the input tables. If column count or column data types are inconsistent, an IOException is thrown.

This utility method is not used by ConcatStarTable instances, but it may be useful when preparing metadata tables for use with the constructor.

Parameters:

colInfos - input column metadata objects

tables - list of tables with which columns must be compatible

Returns:

new array of new column metadata objects, based on input list

Throws:

IOException - if compatibility cannot be achieved