casacore::ScalarQuantColumn< T > Class Template Reference

Provides access to Scalar Quantum Columns in Tables. More...

#include <ScalarQuantColumn.h>

Public Member Functions
	ScalarQuantColumn ()
	The default constructor creates a null object.
	ScalarQuantColumn (const Table &tab, const String &columnName)
	Create the ScalarQuantColumn from the specified table and column name.
	ScalarQuantColumn (const Table &tab, const String &columnName, const Unit &)
	Create the ScalarQuantColumn from the specified table and column name.
	ScalarQuantColumn (const ScalarQuantColumn< T > &that)
	Copy constructor (copy semantics).
	~ScalarQuantColumn ()
void	reference (const ScalarQuantColumn< T > &that)
	Change the reference to another column.
Quantum< T >	operator() (uInt rownr) const
	Return the quantum stored in the specified row.
Quantum< T >	operator() (uInt rownr, const Unit &) const
	Return the quantum stored in the specified row, converted to the given unit.
Quantum< T >	operator() (uInt rownr, const Quantum< T > &other) const
	Return the quantum in the specified row, converted to the unit in other.
void	put (uInt rownr, const Quantum< T > &q)
	Put a quantum into the table.
Bool	isUnitVariable () const
	Test whether the Quantum column has variable units.
const String &	getUnits () const
	Returns the column's value for Units as a string.
Bool	isNull () const
	Test if the object is null.
void	throwIfNull () const
	Throw an exception if the object is null.
SHARED_PTR< Quantum< Vector< T > > >	getColumn (const Unit &unit="") const
	get the column as a Quantum<Vector<T> >.


void	attach (const Table &tab, const String &columnName)
	Attach a column to the object.
void	attach (const Table &tab, const String &columnName, const Unit &)
void	get (uInt rownr, Quantum< T > &q) const
	Get the quantum stored in the specified row.
void	get (uInt rownr, Quantum< T > &q, const Unit &) const
	Get the quantum in the specified row, converted to the given unit.
void	get (uInt rownr, Quantum< T > &q, const Quantum< T > &other) const
	Get the quantum in the specified row, converted to the unit in other.
Protected Member Functions
const ScalarColumn< String > *	unitsCol () const
	Get access to itsUnitsCol.
Protected Attributes
Unit	itsUnit
Private Member Functions
ScalarQuantColumn &	operator= (const ScalarQuantColumn< T > &that)
	Assignment makes no sense in a read only class.
Bool	operator== (const ScalarQuantColumn< T > &that)
	Comparison is not defined, since its semantics are unclear.
void	init (const Table &tab, const String &columnName)
	Initialize the ScalarQuantColumn from the specified table and column.
void	cleanUp ()
	Deletes allocated memory etc.
void	getData (uInt rownr, Quantum< T > &q) const
	Get the data without possible conversion.
Private Attributes
ScalarColumn< T > *	itsDataCol
ScalarColumn< String > *	itsUnitsCol
Unit	itsUnitOut
Bool	itsConvOut

Detailed Description

template<class T>
class casacore::ScalarQuantColumn< T >

Provides access to Scalar Quantum Columns in Tables.

Intended use:

Public interface

Review Status

Reviewed By:: Bob Garwood
Date Reviewed:: 1999/12/23
Test programs:: tTableQuantum

Prerequisite

Synopsis

The ScalarQuantColumn class provides read/write access to quanta stored in a scalar Quantum Table column. The Quantum column should already exist in the table and would have been defined by means of a TableQuantumDesc object . In addition, for a ScalarQuantColumn object to be useful the column should contain Quanta.

A ScalarQuantColumn object is used much in the same way as a ScalarColumn object.

Quantum Units

Quanta retrieved from the column will normally have the Unit that was specified when the Quantum column was defined. However, it is possible to override the default column Unit by supplying a Unit in the ScalarQuantColumn constructor. When constructed in this fashion the retrieved Quanta will by default be retrieved in this unit, i.e. they will by default be converted to this unit.
By giving a unit (as a Unit or Quantum object) to a get function, the data can be retrieved in another unit than the default.

Example

 Quantum<Double> q(5.3, "keV");
 // "QuantScalar" has previously been defined as a Quantum column
 // by means of a TableQuantumDesc. This example assumes the column
 // already contains quanta.
 ScalarQuantColumn<Double> qCol(qtab, "QuantScalar");
 // return and print quanta as stored in the column
 for (i = 0; i < qtab.nrow(); i++) {
 cout << qCol(i) << endl;
 }
 // The following retrieves and converts the quanta to GHz.  They
 // are then divided by the Quantum constant QC::h (Planck).
 for (i=0; i < qtab.nrow(); i++) {
 cout << (qCol(i, "GHz"))/(QC::h);
 }

Motivation

Add support for Quanta in the Tables system.

Thrown Exceptions

TableInvOper if the Table column is null.

To Do

Functions like getColumn

Definition at line 119 of file ScalarQuantColumn.h.

Constructor & Destructor Documentation

template<class T>

casacore::ScalarQuantColumn< T >::ScalarQuantColumn ( )

The default constructor creates a null object.

It is useful for creating arrays of ScalarQuantColumn objects. Attempting to use a null object will produce a segmentation fault so care needs to be taken to initialise the objects by using the attach() member before any attempt is made to use the object. The isNull() member can be used to test if a ScalarQuantColumn object is null.

template<class T>

casacore::ScalarQuantColumn< T >::ScalarQuantColumn	(	const Table &	tab,
		const String &	columnName
	)

Create the ScalarQuantColumn from the specified table and column name.

The default unit for data retrieved is the unit in which they were stored.

template<class T>

casacore::ScalarQuantColumn< T >::ScalarQuantColumn	(	const Table &	tab,
		const String &	columnName,
		const Unit &
	)

Create the ScalarQuantColumn from the specified table and column name.

The default unit for data retrieved is the given unit (the data is converted as needed).

template<class T>

casacore::ScalarQuantColumn< T >::ScalarQuantColumn ( const ScalarQuantColumn< T > & that )

Copy constructor (copy semantics).

template<class T>

casacore::ScalarQuantColumn< T >::~ScalarQuantColumn ( )

Member Function Documentation

template<class T>

void casacore::ScalarQuantColumn< T >::attach	(	const Table &	tab,
		const String &	columnName,
		const Unit &
	)

template<class T>

void casacore::ScalarQuantColumn< T >::attach	(	const Table &	tab,
		const String &	columnName
	)

Attach a column to the object.

Optionally supply a default unit which has the same meaning as the constructor unit argument.

template<class T>

void casacore::ScalarQuantColumn< T >::cleanUp ( ) [private]

Deletes allocated memory etc.

Called by destructor and any member which needs to reallocate data.

template<class T>

void casacore::ScalarQuantColumn< T >::get	(	uInt	rownr,
		Quantum< T > &	q,
		const Quantum< T > &	other
	)			const

Get the quantum in the specified row, converted to the unit in other.

template<class T>

void casacore::ScalarQuantColumn< T >::get	(	uInt	rownr,
		Quantum< T > &	q,
		const Unit &
	)			const

Get the quantum in the specified row, converted to the given unit.

template<class T>

void casacore::ScalarQuantColumn< T >::get	(	uInt	rownr,
		Quantum< T > &	q
	)			const

Get the quantum stored in the specified row.

template<class T>

SHARED_PTR<Quantum<Vector<T> > > casacore::ScalarQuantColumn< T >::getColumn ( const Unit & unit = "" ) const

get the column as a Quantum<Vector<T> >.

If unit is not empty, the returned Quantum will have that unit. Else if the units are variable, the values in the returned Vector have been converted to the unit of the 0th row entry. Otherwise, the units of the returned Quantum are the units specified in the column descriptor.

template<class T>

void casacore::ScalarQuantColumn< T >::getData	(	uInt	rownr,
		Quantum< T > &	q
	)			const `[private]`

Get the data without possible conversion.

template<class T>

const String& casacore::ScalarQuantColumn< T >::getUnits ( ) const [inline]

Returns the column's value for Units as a string.

An empty string is returned if the column has variable units.

Definition at line 187 of file ScalarQuantColumn.h.

template<class T>

void casacore::ScalarQuantColumn< T >::init	(	const Table &	tab,
		const String &	columnName
	)			`[private]`

Initialize the ScalarQuantColumn from the specified table and column.

template<class T>

Bool casacore::ScalarQuantColumn< T >::isNull ( ) const [inline]

Test if the object is null.

Definition at line 191 of file ScalarQuantColumn.h.

template<class T>

Bool casacore::ScalarQuantColumn< T >::isUnitVariable ( ) const [inline]

Test whether the Quantum column has variable units.

Definition at line 182 of file ScalarQuantColumn.h.

template<class T>

Quantum<T> casacore::ScalarQuantColumn< T >::operator()	(	uInt	rownr,
		const Quantum< T > &	other
	)			const

Return the quantum in the specified row, converted to the unit in other.

template<class T>

Quantum<T> casacore::ScalarQuantColumn< T >::operator()	(	uInt	rownr,
		const Unit &
	)			const

Return the quantum stored in the specified row, converted to the given unit.

template<class T>

Quantum<T> casacore::ScalarQuantColumn< T >::operator() ( uInt rownr ) const

Return the quantum stored in the specified row.

template<class T>

ScalarQuantColumn& casacore::ScalarQuantColumn< T >::operator= ( const ScalarQuantColumn< T > & that ) [private]

Assignment makes no sense in a read only class.

Declaring this operator private makes it unusable.

template<class T>

Bool casacore::ScalarQuantColumn< T >::operator== ( const ScalarQuantColumn< T > & that ) [private]

Comparison is not defined, since its semantics are unclear.

template<class T>

void casacore::ScalarQuantColumn< T >::put	(	uInt	rownr,
		const Quantum< T > &	q
	)

Put a quantum into the table.

If the column supports variable units the q's unit is stored into the unit column defined in the TableQuantumDesc object. If units are fixed for the column, the quantum is converted as needed.

template<class T>

void casacore::ScalarQuantColumn< T >::reference ( const ScalarQuantColumn< T > & that )

Change the reference to another column.

template<class T>

void casacore::ScalarQuantColumn< T >::throwIfNull ( ) const

Throw an exception if the object is null.

template<class T>

const ScalarColumn<String>* casacore::ScalarQuantColumn< T >::unitsCol ( ) const [inline, protected]

Get access to itsUnitsCol.

Definition at line 210 of file ScalarQuantColumn.h.