Read only access to table array Measure columns. More...

#include <ArrayMeasColumn.h>

Inheritance diagram for casa::ArrayMeasColumn< M >:

Public Member Functions
	ArrayMeasColumn ()
	The default constructor creates a null object.
	ArrayMeasColumn (const Table &tab, const String &columnName)
	Create the ArrayMeasColumn from the table and column Name.
	ArrayMeasColumn (const ArrayMeasColumn< M > &that)
	Copy constructor (copy semantics).
virtual	~ArrayMeasColumn ()
void	reference (const ArrayMeasColumn< M > &that)
	Change the reference to another column.
void	attach (const Table &tab, const String &columnName)
	Attach a column to the object.
Array< M >	convert (uInt rownr, const M &meas) const
	Get the Measure array contained in the specified row and convert it to the reference and offset found in the given measure.
Array< M >	convert (uInt rownr, const MeasRef< M > &measRef) const
	Get the Measure array contained in the specified row and convert it to the given reference.
Array< M >	convert (uInt rownr, uInt refCode) const
const MeasRef< M > &	getMeasRef () const
	Get the column's reference.
void	setDescRefCode (uInt refCode, Bool tableMustBeEmpty=True)
	Reset the refCode, offset, or units.
void	setDescOffset (const Measure &offset, Bool tableMustBeEmpty=True)
void	setDescUnits (const Vector< Unit > &units, Bool tableMustBeEmpty=True)

void	get (uInt rownr, Array< M > &meas, Bool resize=False) const
	Get the Measure array in the specified row.
Array< M >	operator() (uInt rownr) const

void	put (uInt rownr, const Array< M > &)
	Add a Measure array to the specified row.
Protected Attributes
MeasRef< M >	itsMeasRef
Private Member Functions
ArrayMeasColumn &	operator= (const ArrayMeasColumn< M > &that)
	Assignment makes no sense in a read only class.
void	cleanUp ()
	Deletes allocated memory etc.
Array< M >	doConvert (uInt rownr, typename M::Convert &conv) const
	Get the data and convert using conversion engine.
Private Attributes
ArrayColumn< Double > *	itsDataCol
ScalarColumn< Int > *	itsRefIntCol
ArrayColumn< Int > *	itsArrRefIntCol
ScalarColumn< String > *	itsRefStrCol
ArrayColumn< String > *	itsArrRefStrCol
ScalarMeasColumn< M > *	itsOffsetCol
ArrayMeasColumn< M > *	itsArrOffsetCol

Detailed Description

template<class M>
class casa::ArrayMeasColumn< M >

Read only access to table array Measure columns.

Intended use:

Public interface

Review Status

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

Prerequisite

Measures
Tables
TableMeasDesc

Synopsis

ArrayMeasColumn objects can be used to access array Measure Columns in tables, both for reading and writing (if the table is writable).

Before a column can be accessed it must have previously been defined as a Measure column by use of the TableMeasDesc object.

The ArrayMeasColumn class is templated on Measure type and MeasValue type but typedefs exist for making declaration less long winded. The Measure classes (like MEpoch) have typedefs ArrayColumn to assist in creating ArrayMeasColumn objects.

Constructing array Measure column objects using these typedefs looks like this:

    // Read/write MEpoch array column
    MEpoch::ArrayColumn ec(table, "ColumnName);

Reading and writing Measures

The reading and writing of Measures columns is very similar to reading and writing of "ordinary" Table columns. get() and operator() exist for reading Measures and the put() member for adding Measures to a column. (put() is obviously not defined for ScalarMeasColumn objects.) Each of these members accepts a row number as an argument.

Care needs to be taken when adding Measures to a column. The user needs to be aware that Measures are not checked for consistency, with respect to a Measure's reference, between the Measures being added to a column and the column's predefined Measure reference. This is only an issue if the Measure column was defined to have a fixed reference. For such columns the reference component of Measures added to a column is silently ignored, that is, there is no warning nor is there any sort of conversion to the column's reference should the reference of the added Measure be different from the column's reference. The functions

TableMeasDescBase::isRefVariable() and

ArrayMeasColumn::getMeasRef() can be used to discover a Measure column's Measure reference characteristics.

Example

       // create an MEpoch array column object
       ArrayMeasColumn<MEpoch> arrayCol;
   
       // should be null.  Can test this and attach a real MEpoch column
       // The column Time1Arr should exist in the table and would have been
       // defined by using a TableMeasDesc
       if (arrayCol.isNull()) {
            arrayCol.attach(tab, "Time1Arr");
       }
   
       // This would throw an Exception if the object is still null....but
       // hopefully won't
       arrayCol.throwIfNull();
   
       // create a vector of MEpochs
       MEpoch last(Quantity(13.45, "h"), MEpoch::Ref(MEpoch::TAI));
       Vector<MEpoch> ev(10);
       for (uInt i=0; i<10; i++) {
           last.set(Quantity(13.45 + i, "h"));
           ev(i) = last;
       }
   
       // before adding something check the isDefined() member
       if (!arrayCol.isDefined(0)) {
           cout << "PASS - nothing in the measure array column row yet\n";
       } else {
           cout << "FAIL - there shouldn't be a valid value in the row!\n";
       }
   
       // add the MEpoch vector to the array Measure column at row 0
       arrayCol.put(0, ev);
   
       // now read the array from the row.  Could use same object to do this
       // but here we'll create a ArrayMeasColumn<MEpoch> to do this
       ArrayMeasColumn<MEpoch> roArrCol(tab, "Time1Arr");
   
       // need a vector to put the MEpochs into
       Vector<MEpoch> ew;
   
       // setting the resize parameter to True automatically sets ew to the
       // same shape as the array contained in the row
       arrayCol.get(0, ew, True);

Motivation

The standard Casacore Table system does not support array Measure columns. This class overcomes this limitation.

Thrown Exceptions

ArrayConformanceError during get() if supplied array is the wrong shape.

Definition at line 170 of file ArrayMeasColumn.h.

Constructor & Destructor Documentation

template<class M>

casa::ArrayMeasColumn< M >::ArrayMeasColumn ( )

The default constructor creates a null object.

Useful for creating arrays of ArrayMeasColumn 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. A ArrayMeasColumn object can be tested if it is null by using the isNull() member.

template<class M>

casa::ArrayMeasColumn< M >::ArrayMeasColumn	(	const Table &	tab,
		const String &	columnName
	)

Create the ArrayMeasColumn from the table and column Name.

template<class M>

casa::ArrayMeasColumn< M >::ArrayMeasColumn ( const ArrayMeasColumn< M > & that )

Copy constructor (copy semantics).

template<class M>

virtual casa::ArrayMeasColumn< M >::~ArrayMeasColumn ( ) [virtual]

Member Function Documentation

template<class M>

void casa::ArrayMeasColumn< M >::attach	(	const Table &	tab,
		const String &	columnName
	)

Attach a column to the object.

Reimplemented from casa::TableMeasColumn.

template<class M>

void casa::ArrayMeasColumn< M >::cleanUp ( ) [private]

Deletes allocated memory etc.

Called by ~tor and any member which needs to reallocate data.

template<class M>

Array<M> casa::ArrayMeasColumn< M >::convert	(	uInt	rownr,
		const M &	meas
	)		const `[inline]`

Get the Measure array contained in the specified row and convert it to the reference and offset found in the given measure.

Definition at line 204 of file ArrayMeasColumn.h.

Referenced by casa::ArrayMeasColumn< MEpoch >::convert().

template<class M>

Array<M> casa::ArrayMeasColumn< M >::convert	(	uInt	rownr,
		const MeasRef< M > &	measRef
	)		const

Get the Measure array contained in the specified row and convert it to the given reference.

template<class M>

Array<M> casa::ArrayMeasColumn< M >::convert	(	uInt	rownr,
		uInt	refCode
	)		const

template<class M>

Array<M> casa::ArrayMeasColumn< M >::doConvert	(	uInt	rownr,
		typename M::Convert &	conv
	)		const `[private]`

Get the data and convert using conversion engine.

template<class M>

void casa::ArrayMeasColumn< M >::get	(	uInt	rownr,
		Array< M > &	meas,
		Bool	resize = `False`
	)		const

Get the Measure array in the specified row.

For get() the supplied array's shape should match the shape in the row unless resize is True.

template<class M>

const MeasRef<M>& casa::ArrayMeasColumn< M >::getMeasRef ( ) const [inline]

Get the column's reference.

Definition at line 215 of file ArrayMeasColumn.h.

template<class M>

Array<M> casa::ArrayMeasColumn< M >::operator() ( uInt rownr ) const

template<class M>

ArrayMeasColumn& casa::ArrayMeasColumn< M >::operator= ( const ArrayMeasColumn< M > & that ) [private]

Assignment makes no sense in a read only class.

Declaring this operator private makes it unusable.

template<class M>

void casa::ArrayMeasColumn< M >::put	(	uInt	rownr,
		const Array< M > &
	)

Add a Measure array to the specified row.

template<class M>

void casa::ArrayMeasColumn< M >::reference ( const ArrayMeasColumn< M > & that )

Change the reference to another column.

template<class M>

void casa::ArrayMeasColumn< M >::setDescOffset	(	const Measure &	offset,
		Bool	tableMustBeEmpty = `True`
	)

template<class M>

void casa::ArrayMeasColumn< M >::setDescRefCode	(	uInt	refCode,
		Bool	tableMustBeEmpty = `True`
	)

Reset the refCode, offset, or units.

It overwrites the value used when defining the TableMeasDesc. Resetting the refCode and offset can only be done if they were defined as fixed in the description.
Tip: In principle the functions can only be used if the table is empty, otherwise already written values have thereafter the incorrect reference, offset, or unit; However, it is possible that part of the table is already written and that the entire measure column is filled in later; In that case the reference, offset, or units can be set by using a False tableMustBeEmpty argument;

template<class M>