uk.ac.starlink.ttools.filter

Class CalculatorColumnSupplement

java.lang.Object

uk.ac.starlink.ttools.filter.CalculatorColumnSupplement

All Implemented Interfaces:

ColumnSupplement

public abstract class CalculatorColumnSupplement
extends Object
implements ColumnSupplement

ColumnSupplement whose columns are derived by calculating values based on all the columns of another table. To generate any of the columns of this table, a whole row of the input supplement must be read. Concrete implementations of this abstract class must implement the calculate(java.lang.Object[]) method.

Since:

2 Apr 2012

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
CalculatorColumnSupplement(ColumnSupplement baseSup, ColumnInfo[] outColInfos) Constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract Object[]	calculate(Object[] inRow) Performs the calculations which populate the columns of this table.
SupplementData	createSupplementData(RowData rdata) Returns a new accessor for the values in the columns defined by this object.
Object	getCell(long irow, int icol) Random access read of a cell defined by this object.
int	getColumnCount() Returns the number of columns defined by this object.
ColumnInfo	getColumnInfo(int icol) Returns the column metadata object for a given column.
static double	getDouble(Object value) Utility method to turn an Object into a floating point value.
Object[]	getRow(long irow) Random access read of a row defined by this object.

Methods inherited from class java.lang.Object

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

Constructor Detail

CalculatorColumnSupplement

public CalculatorColumnSupplement(ColumnSupplement baseSup,
                                  ColumnInfo[] outColInfos)

Constructor.

Parameters:

baseSup - base supplement

outColInfos - column metadata for the supplementary columns (length defines column count)

Method Detail

calculate

protected abstract Object[] calculate(Object[] inRow)
                               throws IOException

Performs the calculations which populate the columns of this table. The input is a row of the base table, and the output is the row of this table.

The implementation must return a new array each time, not repopulate the same Object[] array object.

Parameters:

inRow - input column values

Returns:

output column values (same size as column count)

Throws:

IOException

getColumnCount

public int getColumnCount()

Description copied from interface: ColumnSupplement

Returns the number of columns defined by this object.

Specified by:

getColumnCount in interface ColumnSupplement

Returns:

number of columns

getColumnInfo

public ColumnInfo getColumnInfo(int icol)

Description copied from interface: ColumnSupplement

Returns the column metadata object for a given column.

Specified by:

getColumnInfo in interface ColumnSupplement

Parameters:

icol - column index within this object

Returns:

column metadata for the icol'th column defined by this object

getRow

public Object[] getRow(long irow)
                throws IOException

Description copied from interface: ColumnSupplement

Random access read of a row defined by this object.

Specified by:

getRow in interface ColumnSupplement

Parameters:

irow - row index

Returns:

array of cell contents for all the cells in this row

Throws:

IOException

getCell

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

Description copied from interface: ColumnSupplement

Random access read of a cell defined by this object.

Specified by:

getCell in interface ColumnSupplement

Parameters:

irow - row index

icol - column index

Returns:

cell content

Throws:

IOException

createSupplementData

public SupplementData createSupplementData(RowData rdata)
                                    throws IOException

Description copied from interface: ColumnSupplement

Returns a new accessor for the values in the columns defined by this object. The supplied row object must be from an appropriate host table; if not, behaviour is undefined.

Specified by:

createSupplementData in interface ColumnSupplement

Parameters:

rdata - row accessor providing data from the host table

Returns:

accessor over row data from supplementary columns

Throws:

IOException

getDouble

public static double getDouble(Object value)

Utility method to turn an Object into a floating point value. If the submitted value is not a Number (including if it is null), NaN will be returned.

Parameters:

value - object value

Returns:

floating point value