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//# Copyright (C) 1994,1995,1996,1999,2001
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: aips2-request@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
//#
//# $Id$
#ifndef TABLES_SCALEDARRAYENGINE_H
#define TABLES_SCALEDARRAYENGINE_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/tables/DataMan/BaseMappedArrayEngine.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
//# Forward Declarations
template<class T> class ScalarColumn;
// <summary>
// Templated virtual column engine to scale a table array
// </summary>
// <use visibility=export>
// <reviewed reviewer="Gareth Hunt" date="94Nov17" tests="">
// </reviewed>
// <prerequisite>
//# Classes you should understand before using this one.
// <li> VirtualColumnEngine
// <li> VirtualArrayColumn
// </prerequisite>
// <synopsis>
// ScaledArrayEngine is a virtual column engine which scales an array
// of one type to another type to save disk storage.
// This resembles the classic AIPS compress method which scales the
// data from float to short.
// The scale factor and offset value can be given in two ways:
// <ul>
// <li> As a fixed value which is used for all arrays in the column.
// <li> As the name of a column. In this way each array in a
// column can have its own scale and offset value.
// The scale and offset value in a row must be put before
// the array is put and should not be changed anymore.
// </ul>
// It is also possible to have a variable scale factor with a fixed offset
// value.
// As in FITS the scale and offset values are used as:
// <br><src> True_value = Stored_value * scale + offset; </src>
//
// An engine object should be used for one column only, because the stored
// column name is part of the engine. If it would be used for more than
// one column, they would all share the same stored column.
// When the engine is bound to a column, it is checked if the name
// of that column matches the given virtual column name.
//
// The engine can be used for a column containing any kind of array
// (thus direct or indirect, fixed or variable shaped)) as long as the
// virtual array can be stored in the stored array. Thus a fixed shaped
// virtual can use a variable shaped stored, but not vice versa.
// A fixed shape indirect virtual can use a stored with direct arrays.
//
// This class can also serve as an example of how to implement
// a virtual column engine.
// </synopsis>
// <motivation>
// This class allows to store data in a smaller representation.
// It is needed to resemble the classic AIPS compress option.
// It adds the scale and offset value on a per row basis.
//
// Because the engine can serve only one column, it was possible to
// combine the engine and the column functionality in one class.
// This has been achieved using multiple inheritance.
// The advantage of this is that only one templated class is used,
// so less template instantiations are needed.
// </motivation>
// <example>
// <srcblock>
// // Create the table description and 2 columns with indirect arrays in it.
// // The Int column will be stored, while the double will be
// // used as virtual.
// TableDesc tableDesc ("", TableDesc::Scratch);
// tableDesc.addColumn (ArrayColumnDesc<Int> ("storedArray"));
// tableDesc.addColumn (ArrayColumnDesc<double> ("virtualArray"));
//
// // Create a new table using the table description.
// SetupNewTable newtab (tableDesc, "tab.data", Table::New);
//
// // Create the array scaling engine to scale from double to Int
// // and bind it to the double column.
// // Create the table.
// ScaledArrayEngine<double,Int> scalingEngine("virtualArray",
// "storedArray", 10);
// newtab.bindColumn ("virtualArray", scalingEngine);
// Table table (newtab);
//
// // Store a 3-D array (with dim. 2,3,4) into each row of the column.
// // The shape of each array in the column is implicitly set by the put
// // function. This will also set the shape of the underlying Int array.
// ArrayColumn data (table, "virtualArray");
// Array<double> someArray(IPosition(4,2,3,4));
// someArray = 0;
// for (uInt i=0, i<10; i++) { // table will have 10 rows
// table.addRow();
// data.put (i, someArray)
// }
// </srcblock>
// </example>
// <templating arg=VirtualType>
// <li> only suited for built-in numerics data types
// </templating>
// <templating arg=StoredType>
// <li> only suited for built-in numerics data types
// </templating>
template<class VirtualType, class StoredType> class ScaledArrayEngine : public BaseMappedArrayEngine<VirtualType, StoredType>
{
//# Make members of parent class known.
public:
using BaseMappedArrayEngine<VirtualType,StoredType>::virtualName;
protected:
using BaseMappedArrayEngine<VirtualType,StoredType>::storedName;
using BaseMappedArrayEngine<VirtualType,StoredType>::table;
using BaseMappedArrayEngine<VirtualType,StoredType>::column;
using BaseMappedArrayEngine<VirtualType,StoredType>::setNames;
public:
// Construct an engine to scale all arrays in a column with
// the given offset and scale factor.
// StoredColumnName is the name of the column where the scaled
// data will be put and must have data type StoredType.
// The virtual column using this engine must have data type VirtualType.
ScaledArrayEngine (const String& virtualColumnName,
const String& storedColumnName,
VirtualType scale,
VirtualType offset = 0);
// Construct an engine to scale the arrays in a column.
// The scale and offset values are taken from a column with
// the given names. In that way each array has its own scale factor
// and offset value.
// An exception is thrown if these columns do not exist.
// VirtualColumnName is the name of the virtual column and is used to
// check if the engine gets bound to the correct column.
// StoredColumnName is the name of the column where the scaled
// data will be put and must have data type StoredType.
// The virtual column using this engine must have data type VirtualType.
// <group>
ScaledArrayEngine (const String& virtualColumnName,
const String& storedColumnName,
const String& scaleColumnName,
VirtualType offset = 0);
ScaledArrayEngine (const String& virtualColumnName,
const String& storedColumnName,
const String& scaleColumnName,
const String& offsetColumnName);
// </group>
// Construct from a record specification as created by getmanagerSpec().
ScaledArrayEngine (const Record& spec);
// Destructor is mandatory.
~ScaledArrayEngine();
// Return the type name of the engine (i.e. its class name).
virtual String dataManagerType() const;
// Get the name given to the engine (is the virtual column name).
virtual String dataManagerName() const;
// Record a record containing data manager specifications.
virtual Record dataManagerSpec() const;
// Return the name of the class.
// This includes the names of the template arguments.
static String className();
// Register the class name and the static makeObject "constructor".
// This will make the engine known to the table system.
// The automatically invoked registration function in DataManReg.cc
// contains ScaledArrayEngine<double,Int>.
// Any other instantiation of this class must be registered "manually"
// (or added to DataManReg.cc).
static void registerClass();
private:
// Copy constructor is only used by clone().
// (so it is made private).
ScaledArrayEngine (const ScaledArrayEngine<VirtualType,StoredType>&);
// Assignment is not needed and therefore forbidden
// (so it is made private and not implemented).
ScaledArrayEngine<VirtualType,StoredType>& operator=
(const ScaledArrayEngine<VirtualType,StoredType>&);
// Clone the engine object.
DataManager* clone() const;
// Initialize the object for a new table.
// It defines the keywords containing the engine parameters.
void create (uInt initialNrrow);
// Preparing consists of setting the writable switch and
// adding the initial number of rows in case of create.
// Furthermore it reads the keywords containing the engine parameters.
void prepare();
// Get an array in the given row.
// This will scale and offset from the underlying array.
void getArray (uInt rownr, Array<VirtualType>& array);
// Put an array in the given row.
// This will scale and offset to the underlying array.
void putArray (uInt rownr, const Array<VirtualType>& array);
// Get a section of the array in the given row.
// This will scale and offset from the underlying array.
void getSlice (uInt rownr, const Slicer& slicer, Array<VirtualType>& array);
// Put into a section of the array in the given row.
// This will scale and offset to the underlying array.
void putSlice (uInt rownr, const Slicer& slicer,
const Array<VirtualType>& array);
// Get an entire column.
// This will scale and offset from the underlying array.
void getArrayColumn (Array<VirtualType>& array);
// Put an entire column.
// This will scale and offset to the underlying array.
void putArrayColumn (const Array<VirtualType>& array);
// Get a section of all arrays in the column.
// This will scale and offset from the underlying array.
void getColumnSlice (const Slicer& slicer, Array<VirtualType>& array);
// Put a section of all arrays in the column.
// This will scale and offset to the underlying array.
void putColumnSlice (const Slicer& slicer, const Array<VirtualType>& array);
// Scale and/or offset stored to array.
// This is meant when reading an array from the stored column.
// It optimizes for scale=1 and/or offset=0.
void scaleOnGet (VirtualType scale, VirtualType offset,
Array<VirtualType>& array,
const Array<StoredType>& stored);
// Scale and/or offset array to stored.
// This is meant when writing an array into the stored column.
// It optimizes for scale=1 and/or offset=0.
void scaleOnPut (VirtualType scale, VirtualType offset,
const Array<VirtualType>& array,
Array<StoredType>& stored);
// Scale and/or offset stored to array for the entire column.
// When the scale and offset are fixed, it will do the entire array.
// Otherwise it iterates through the array and applies the scale
// and offset per row.
void scaleColumnOnGet (Array<VirtualType>& array,
const Array<StoredType>& stored);
// Scale and/or offset array to stored for the entire column.
// When the scale and offset are fixed, it will do the entire array.
// Otherwise it iterates through the array and applies the scale
// and offset per row.
void scaleColumnOnPut (const Array<VirtualType>& array,
Array<StoredType>& stored);
//# Now define the data members.
String scaleName_p; //# name of scale column
String offsetName_p; //# name of offset column
VirtualType scale_p; //# scale factor
VirtualType offset_p; //# offset value
Bool fixedScale_p; //# scale is a fixed column
Bool fixedOffset_p; //# scale is a fixed column
ScalarColumn<VirtualType>* scaleColumn_p; //# column with scale value
ScalarColumn<VirtualType>* offsetColumn_p; //# column with offset value
// Get the scale value for this row.
VirtualType getScale (uInt rownr);
// Get the offset value for this row.
VirtualType getOffset (uInt rownr);
public:
//*display 4
// Define the "constructor" to construct this engine when a
// table is read back.
// This "constructor" has to be registered by the user of the engine.
// If the engine is commonly used, its registration can be added
// to the registerAllCtor function in DataManReg.cc.
// That function gets automatically invoked by the table system.
static DataManager* makeObject (const String& dataManagerType,
const Record& spec);
};
} //# NAMESPACE CASACORE - END
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/tables/DataMan/ScaledArrayEngine.tcc>
#endif //# CASACORE_NO_AUTO_TEMPLATES
#endif
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