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casacore::ArrayMeasColumn< M > Class Template Reference

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

#include <MDirection.h>

Inheritance diagram for casacore::ArrayMeasColumn< M >:
casacore::TableMeasColumn

Public Member Functions

 ArrayMeasColumn ()
 The default constructor creates a null object. More...
 
 ArrayMeasColumn (const Table &tab, const String &columnName)
 Create the ArrayMeasColumn from the table and column Name. More...
 
 ArrayMeasColumn (const ArrayMeasColumn< M > &that)
 Copy constructor (copy semantics). More...
 
virtual ~ArrayMeasColumn ()
 
void reference (const ArrayMeasColumn< M > &that)
 Change the reference to another column. More...
 
void attach (const Table &tab, const String &columnName)
 Attach a column to the object. More...
 
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. More...
 
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. More...
 
Array< M > convert (uInt rownr, uInt refCode) const
 
const MeasRef< M > & getMeasRef () const
 Get the column's reference. More...
 
void setDescRefCode (uInt refCode, Bool tableMustBeEmpty=True)
 Reset the refCode, offset, or units. More...
 
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. More...
 
Array< M > operator() (uInt rownr) const
 
void put (uInt rownr, const Array< M > &)
 Add a Measure array to the specified row. More...
 
- Public Member Functions inherited from casacore::TableMeasColumn
 TableMeasColumn ()
 The default constructor creates a null object. More...
 
 TableMeasColumn (const Table &tab, const String &columnName)
 Create the ScalarMeasColumn from the table and column Name. More...
 
 TableMeasColumn (const TableMeasColumn &that)
 Copy constructor (copy semantics). More...
 
virtual ~TableMeasColumn ()
 
void reference (const TableMeasColumn &that)
 Change the reference to another column. More...
 
void attach (const Table &tab, const String &columnName)
 Attach another column to the object. More...
 
Bool isDefined (uInt rownr) const
 Tests if a row contains a Measure (i.e., if the row has a defined value). More...
 
const TableMeasDescBasemeasDesc () const
 Get access to the TableMeasDescBase describing the column. More...
 
TableMeasDescBasemeasDesc ()
 
Bool isNull () const
 Test if the object is null. More...
 
void throwIfNull () const
 Throw an exception if the object is null. More...
 
const StringcolumnName () const
 Get the name of the column. More...
 
Table table () const
 Get the Table object this column belongs to. More...
 
Bool isScalar () const
 Is the column a scalar measures column? It is if the underlying column is a scalar column or an array column with a fixed 1-dimensional shape. More...
 

Protected Attributes

MeasRef< M > itsMeasRef
 
- Protected Attributes inherited from casacore::TableMeasColumn
uInt itsNvals
 
CountedPtr< TableMeasDescBaseitsDescPtr
 
TableColumn itsTabDataCol
 
Bool itsVarRefFlag
 
Bool itsVarOffFlag
 

Private Member Functions

ArrayMeasColumnoperator= (const ArrayMeasColumn< M > &that)
 Assignment makes no sense in a read only class. More...
 
void cleanUp ()
 Deletes allocated memory etc. More...
 
Array< M > doConvert (uInt rownr, typename M::Convert &conv) const
 Get the data and convert using conversion engine. More...
 

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 casacore::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

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

Definition at line 44 of file MDirection.h.

Constructor & Destructor Documentation

template<class M>
casacore::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>
casacore::ArrayMeasColumn< M >::ArrayMeasColumn ( const Table tab,
const String columnName 
)

Create the ArrayMeasColumn from the table and column Name.

template<class M>
casacore::ArrayMeasColumn< M >::ArrayMeasColumn ( const ArrayMeasColumn< M > &  that)

Copy constructor (copy semantics).

template<class M>
virtual casacore::ArrayMeasColumn< M >::~ArrayMeasColumn ( )
virtual

Member Function Documentation

template<class M>
void casacore::ArrayMeasColumn< M >::attach ( const Table tab,
const String columnName 
)

Attach a column to the object.

template<class M>
void casacore::ArrayMeasColumn< M >::cleanUp ( )
private

Deletes allocated memory etc.

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

template<class M>
Array<M> casacore::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 205 of file ArrayMeasColumn.h.

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

template<class M>
Array<M> casacore::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> casacore::ArrayMeasColumn< M >::convert ( uInt  rownr,
uInt  refCode 
) const
template<class M>
Array<M> casacore::ArrayMeasColumn< M >::doConvert ( uInt  rownr,
typename M::Convert &  conv 
) const
private

Get the data and convert using conversion engine.

template<class M>
void casacore::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>& casacore::ArrayMeasColumn< M >::getMeasRef ( ) const
inline

Get the column's reference.

Definition at line 216 of file ArrayMeasColumn.h.

template<class M>
Array<M> casacore::ArrayMeasColumn< M >::operator() ( uInt  rownr) const
template<class M>
ArrayMeasColumn& casacore::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 casacore::ArrayMeasColumn< M >::put ( uInt  rownr,
const Array< M > &   
)

Add a Measure array to the specified row.

template<class M>
void casacore::ArrayMeasColumn< M >::reference ( const ArrayMeasColumn< M > &  that)

Change the reference to another column.

template<class M>
void casacore::ArrayMeasColumn< M >::setDescOffset ( const Measure offset,
Bool  tableMustBeEmpty = True 
)
template<class M>
void casacore::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>
void casacore::ArrayMeasColumn< M >::setDescUnits ( const Vector< Unit > &  units,
Bool  tableMustBeEmpty = True 
)

Member Data Documentation

template<class M>
ArrayMeasColumn<M>* casacore::ArrayMeasColumn< M >::itsArrOffsetCol
private

Definition at line 259 of file ArrayMeasColumn.h.

template<class M>
ArrayColumn<Int>* casacore::ArrayMeasColumn< M >::itsArrRefIntCol
private

Definition at line 252 of file ArrayMeasColumn.h.

template<class M>
ArrayColumn<String>* casacore::ArrayMeasColumn< M >::itsArrRefStrCol
private

Definition at line 255 of file ArrayMeasColumn.h.

template<class M>
ArrayColumn<Double>* casacore::ArrayMeasColumn< M >::itsDataCol
private

Definition at line 249 of file ArrayMeasColumn.h.

template<class M>
MeasRef<M> casacore::ArrayMeasColumn< M >::itsMeasRef
protected

Definition at line 245 of file ArrayMeasColumn.h.

Referenced by casacore::ArrayMeasColumn< MEpoch >::getMeasRef().

template<class M>
ScalarMeasColumn<M>* casacore::ArrayMeasColumn< M >::itsOffsetCol
private

Definition at line 258 of file ArrayMeasColumn.h.

template<class M>
ScalarColumn<Int>* casacore::ArrayMeasColumn< M >::itsRefIntCol
private

Definition at line 251 of file ArrayMeasColumn.h.

template<class M>
ScalarColumn<String>* casacore::ArrayMeasColumn< M >::itsRefStrCol
private

Definition at line 254 of file ArrayMeasColumn.h.


The documentation for this class was generated from the following files: