casacore
CompressFloat.h
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1//# CompressFloat.h: Virtual column engine to scale a table float array
2//# Copyright (C) 2001,2002
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//# $Id$
27
28#ifndef TABLES_COMPRESSFLOAT_H
29#define TABLES_COMPRESSFLOAT_H
30
31//# Includes
32#include <casacore/casa/aips.h>
33#include <casacore/tables/DataMan/BaseMappedArrayEngine.h>
34#include <casacore/tables/Tables/ScalarColumn.h>
35#include <casacore/casa/Arrays/Array.h>
36
37
38namespace casacore { //# NAMESPACE CASACORE - BEGIN
39
40// <summary>
41// Virtual column engine to scale a table float array
42// </summary>
43
44// <use visibility=export>
45
46// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tCompressFloat.cc">
47// </reviewed>
48
49// <prerequisite>
50//# Classes you should understand before using this one.
51// <li> VirtualColumnEngine
52// <li> VirtualArrayColumn
53// </prerequisite>
54
55// <synopsis>
56// CompressFloat is a virtual column engine which scales an array
57// of one type to another type to save disk storage.
58// This resembles the classic AIPS compress method which scales the
59// data from float to short.
60// The scale factor and offset values can be given in two ways:
61// <ul>
62// <li> As a fixed values which is used for all arrays in the column.
63// These values have to be given when constructing of the engine.
64// <li> As the name of a column. In this way each array in the
65// column has its own scale and offset value.
66// By default it uses auto-scaling (see below).
67// Otherwise the scale and offset value in a row must be put
68// before the array is put and should not be changed anymore.
69// </ul>
70// Auto-scaling means that the engine will determine the scale
71// and offset value itself when an array (or a slice) is put.
72// It does it by mapping the values in the array to the range [-32767,32767].
73// At each put the scale/offset values are changed as needed.
74// Note that with auto-scaling <src>putSlice</src> can be somewhat
75// slower, because the entire array might need to be rescaled.
76//
77// As in FITS the scale and offset values are used as:
78// <br><src> True_value = Stored_value * scale + offset; </src>
79//
80// An engine object should be used for one column only, because the stored
81// column name is part of the engine. If it would be used for more than
82// one column, they would all share the same stored column.
83// When the engine is bound to a column, it is checked if the name
84// of that column matches the given virtual column name.
85//
86// The engine can be used for a column containing any kind of array
87// (thus direct or indirect, fixed or variable shaped)) as long as the
88// virtual array can be stored in the stored array. Thus a fixed shaped
89// virtual can use a variable shaped stored, but not vice versa.
90// A fixed shape indirect virtual can use a stored with direct arrays.
91//
92// This class can also serve as an example of how to implement
93// a virtual column engine.
94// </synopsis>
95
96// <motivation>
97// This class allows to store data in a smaller representation.
98// It is needed to resemble the classic AIPS compress option.
99//
100// Because the engine can serve only one column, it was possible to
101// combine the engine and the column functionality in one class.
102// </motivation>
103
104// <example>
105// <srcblock>
106// // Create the table description and 2 columns with indirect arrays in it.
107// // The Int column will be stored, while the double will be
108// // used as virtual.
109// TableDesc tableDesc ("", TableDesc::Scratch);
110// tableDesc.addColumn (ArrayColumnDesc<Short> ("storedArray"));
111// tableDesc.addColumn (ArrayColumnDesc<Float> ("virtualArray"));
112// tableDesc.addColumn (ScalarColumnDesc<Float> ("scale"));
113// tableDesc.addColumn (ScalarColumnDesc<Float> ("offset"));
114//
115// // Create a new table using the table description.
116// SetupNewTable newtab (tableDesc, "tab.data", Table::New);
117//
118// // Create the array scaling engine (with auto-scale)
119// // and bind it to the float column.
120// CompressFloat scalingEngine("virtualArray", "storedArray",
121// "scale", "offset");
122// newtab.bindColumn ("virtualArray", scalingEngine);
123// // Create the table.
124// Table table (newtab);
125//
126// // Store a 3-D array (with dim. 2,3,4) into each row of the column.
127// // The shape of each array in the column is implicitly set by the put
128// // function. This will also set the shape of the underlying Int array.
129// ArrayColumn data (table, "virtualArray");
130// Array<double> someArray(IPosition(4,2,3,4));
131// someArray = 0;
132// for (rownr_t i=0, i<10; i++) { // table will have 10 rows
133// table.addRow();
134// data.put (i, someArray)
135// }
136// </srcblock>
137// </example>
138
139class CompressFloat : public BaseMappedArrayEngine<Float, Short>
140{
141public:
142
143 // Construct an engine to scale all arrays in a column with
144 // the given offset and scale factor.
145 // StoredColumnName is the name of the column where the scaled
146 // data will be put and must have data type Short.
147 // The virtual column using this engine must have data type Float.
148 CompressFloat (const String& virtualColumnName,
149 const String& storedColumnName,
150 Float scale,
151 Float offset = 0);
152
153 // Construct an engine to scale the arrays in a column.
154 // The scale and offset values are taken from a column with
155 // the given names. In that way each array has its own scale factor
156 // and offset value.
157 // An exception is thrown if these columns do not exist.
158 // VirtualColumnName is the name of the virtual column and is used to
159 // check if the engine gets bound to the correct column.
160 // StoredColumnName is the name of the column where the scaled
161 // data will be put and must have data type Short.
162 // The virtual column using this engine must have data type Float.
163 CompressFloat (const String& virtualColumnName,
164 const String& storedColumnName,
165 const String& scaleColumnName,
166 const String& offsetColumnName,
167 Bool autoScale = True);
168
169 // Construct from a record specification as created by getmanagerSpec().
170 CompressFloat (const Record& spec);
171
172 // Destructor is mandatory.
174
175 // Return the type name of the engine (i.e. its class name).
176 virtual String dataManagerType() const;
177
178 // Get the name given to the engine (is the virtual column name).
179 virtual String dataManagerName() const;
180
181 // Record a record containing data manager specifications.
182 virtual Record dataManagerSpec() const;
183
184 // Return the name of the class.
185 // This includes the names of the template arguments.
187
188 // Register the class name and the static makeObject "constructor".
189 // This will make the engine known to the table system.
190 static void registerClass();
191
192private:
193 // Copy constructor is only used by clone().
194 // (so it is made private).
196
197 // Assignment is not needed and therefore forbidden
198 // (so it is made private and not implemented).
200
201 // Clone the engine object.
202 virtual DataManager* clone() const;
203
204 // Initialize the object for a new table.
205 // It defines the keywords containing the engine parameters.
206 virtual void create64 (rownr_t initialNrrow);
207
208 // Preparing consists of setting the writable switch and
209 // adding the initial number of rows in case of create.
210 // Furthermore it reads the keywords containing the engine parameters.
211 virtual void prepare();
212
213 // Reopen the engine for read/write access.
214 // It makes the column writable if the underlying column is writable.
215 virtual void reopenRW();
216
217 // Add rows to the table.
218 // If auto-scaling, it initializes the scale column with 0
219 // to indicate that no data has been processed yet.
220 virtual void addRowInit (rownr_t startRow, rownr_t nrrow);
221
222 // Get an array in the given row.
223 // This will scale and offset from the underlying array.
224 virtual void getArray (rownr_t rownr, Array<Float>& array);
225
226 // Put an array in the given row.
227 // This will scale and offset to the underlying array.
228 virtual void putArray (rownr_t rownr, const Array<Float>& array);
229
230 // Get a section of the array in the given row.
231 // This will scale and offset from the underlying array.
232 virtual void getSlice (rownr_t rownr, const Slicer& slicer,
234
235 // Put into a section of the array in the given row.
236 // This will scale and offset to the underlying array.
237 virtual void putSlice (rownr_t rownr, const Slicer& slicer,
238 const Array<Float>& array);
239
240 // Get an entire column.
241 // This will scale and offset from the underlying array.
243
244 // Put an entire column.
245 // This will scale and offset to the underlying array.
246 virtual void putArrayColumn (const Array<Float>& array);
247
248 // Get some array values in the column.
249 // This will scale and offset from the underlying array.
250 virtual void getArrayColumnCells (const RefRows& rownrs,
251 Array<Float>& data);
252
253 // Put some array values in the column.
254 // This will scale and offset to the underlying array.
255 virtual void putArrayColumnCells (const RefRows& rownrs,
256 const Array<Float>& data);
257
258 // Get a section of all arrays in the column.
259 // This will scale and offset from the underlying array.
260 virtual void getColumnSlice (const Slicer& slicer, Array<Float>& array);
261
262 // Put a section of all arrays in the column.
263 // This will scale and offset to the underlying array.
264 virtual void putColumnSlice (const Slicer& slicer,
265 const Array<Float>& array);
266
267 // Get a section of some arrays in the column.
268 // This will scale and offset from the underlying array.
269 virtual void getColumnSliceCells (const RefRows& rownrs,
270 const Slicer& slicer,
271 Array<Float>& data);
272
273 // Put into a section of some arrays in the column.
274 // This will scale and offset to the underlying array.
275 virtual void putColumnSliceCells (const RefRows& rownrs,
276 const Slicer& slicer,
277 const Array<Float>& data);
278
279 // Scale and/or offset target to array.
280 // This is meant when reading an array from the stored column.
281 // It optimizes for scale=1 and/or offset=0.
282 void scaleOnGet (Float scale, Float offset,
284 const Array<Short>& target);
285
286 // Scale and/or offset array to target.
287 // This is meant when writing an array into the stored column.
288 // It optimizes for scale=1 and/or offset=0.
289 void scaleOnPut (Float scale, Float offset,
290 const Array<Float>& array,
291 Array<Short>& target);
292
293 // Scale and/or offset target to array for the entire column.
294 // When the scale and offset are fixed, it will do the entire array.
295 // Otherwise it iterates through the array and applies the scale
296 // and offset per row.
298 const Array<Short>& target);
299
300 // Scale and/or offset array to target for the entire column.
301 // When the scale and offset are fixed, it will do the entire array.
302 // Otherwise it iterates through the array and applies the scale
303 // and offset per row.
305 Array<Short>& target);
306
307
308 //# Now define the data members.
309 String scaleName_p; //# name of scale column
310 String offsetName_p; //# name of offset column
311 Float scale_p; //# fixed scale factor
312 Float offset_p; //# fixed offset value
313 Bool fixed_p; //# scale/offset is fixed
314 Bool autoScale_p; //# determine scale/offset automatically
315 ScalarColumn<Float>* scaleColumn_p; //# column with scale value
316 ScalarColumn<Float>* offsetColumn_p; //# column with offset value
317 Array<Short> buffer_p; //# buffer to avoid Array constructions
318
319 // Get the scale value for this row.
320 Float getScale (rownr_t rownr);
321
322 // Get the offset value for this row.
323 Float getOffset (rownr_t rownr);
324
325 // Find minimum and maximum from the array data.
326 // NaN and infinite values are ignored. If no values are finite,
327 // minimum and maximum are set to NaN.
328 void findMinMax (Float& minVal, Float& maxVal,
329 const Array<Float>& array) const;
330
331 // Make scale and offset from the minimum and maximum of the array data.
332 // If minVal is NaN, scale is set to 0.
333 void makeScaleOffset (Float& scale, Float& offset,
334 Float minVal, Float maxVal) const;
335
336 // Put a part of an array in a row using given scale/offset values.
337 void putPart (rownr_t rownr, const Slicer& slicer,
338 const Array<Float>& array,
339 Float scale, Float offset);
340
341 // Fill the array part into the full array and put it using the
342 // given min/max values.
343 void putFullPart (rownr_t rownr, const Slicer& slicer,
344 Array<Float>& fullArray,
345 const Array<Float>& partArray,
346 Float minVal, Float maxVal);
347
348public:
349 // Define the "constructor" to construct this engine when a
350 // table is read back.
351 // This "constructor" has to be registered by the user of the engine.
352 // If the engine is commonly used, its registration can be added
353 // to the registerAllCtor function in DataManager.cc.
354 // That function gets automatically invoked by the table system.
356 const Record& spec);
357};
358
359
361{
362 return (fixed_p ? scale_p : (*scaleColumn_p)(rownr));
363}
365{
366 return (fixed_p ? offset_p : (*offsetColumn_p)(rownr));
367}
368
369
370
371} //# NAMESPACE CASACORE - END
372
373#endif
Float getOffset(rownr_t rownr)
Get the offset value for this row.
virtual Record dataManagerSpec() const
Record a record containing data manager specifications.
virtual void getArray(rownr_t rownr, Array< Float > &array)
Get an array in the given row.
virtual void getColumnSlice(const Slicer &slicer, Array< Float > &array)
Get a section of all arrays in the column.
Float getScale(rownr_t rownr)
Get the scale value for this row.
virtual void getArrayColumn(Array< Float > &array)
Get an entire column.
CompressFloat(const String &virtualColumnName, const String &storedColumnName, const String &scaleColumnName, const String &offsetColumnName, Bool autoScale=True)
Construct an engine to scale the arrays in a column.
virtual void getSlice(rownr_t rownr, const Slicer &slicer, Array< Float > &array)
Get a section of the array in the given row.
CompressFloat(const CompressFloat &)
Copy constructor is only used by clone().
virtual void reopenRW()
Reopen the engine for read/write access.
void findMinMax(Float &minVal, Float &maxVal, const Array< Float > &array) const
Find minimum and maximum from the array data.
void scaleColumnOnGet(Array< Float > &array, const Array< Short > &target)
Scale and/or offset target to array for the entire column.
virtual void putSlice(rownr_t rownr, const Slicer &slicer, const Array< Float > &array)
Put into a section of the array in the given row.
virtual DataManager * clone() const
Clone the engine object.
ScalarColumn< Float > * scaleColumn_p
ScalarColumn< Float > * offsetColumn_p
static String className()
Return the name of the class.
virtual void putArray(rownr_t rownr, const Array< Float > &array)
Put an array in the given row.
virtual void prepare()
Preparing consists of setting the writable switch and adding the initial number of rows in case of cr...
void scaleColumnOnPut(const Array< Float > &array, Array< Short > &target)
Scale and/or offset array to target for the entire column.
~CompressFloat()
Destructor is mandatory.
void scaleOnPut(Float scale, Float offset, const Array< Float > &array, Array< Short > &target)
Scale and/or offset array to target.
static DataManager * makeObject(const String &dataManagerType, const Record &spec)
Define the "constructor" to construct this engine when a table is read back.
virtual void putColumnSliceCells(const RefRows &rownrs, const Slicer &slicer, const Array< Float > &data)
Put into a section of some arrays in the column.
void putFullPart(rownr_t rownr, const Slicer &slicer, Array< Float > &fullArray, const Array< Float > &partArray, Float minVal, Float maxVal)
Fill the array part into the full array and put it using the given min/max values.
static void registerClass()
Register the class name and the static makeObject "constructor".
virtual String dataManagerName() const
Get the name given to the engine (is the virtual column name).
virtual void getArrayColumnCells(const RefRows &rownrs, Array< Float > &data)
Get some array values in the column.
void putPart(rownr_t rownr, const Slicer &slicer, const Array< Float > &array, Float scale, Float offset)
Put a part of an array in a row using given scale/offset values.
virtual void putArrayColumnCells(const RefRows &rownrs, const Array< Float > &data)
Put some array values in the column.
CompressFloat & operator=(const CompressFloat &)
Assignment is not needed and therefore forbidden (so it is made private and not implemented).
CompressFloat(const String &virtualColumnName, const String &storedColumnName, Float scale, Float offset=0)
Construct an engine to scale all arrays in a column with the given offset and scale factor.
virtual void putArrayColumn(const Array< Float > &array)
Put an entire column.
virtual void putColumnSlice(const Slicer &slicer, const Array< Float > &array)
Put a section of all arrays in the column.
virtual void addRowInit(rownr_t startRow, rownr_t nrrow)
Add rows to the table.
virtual void getColumnSliceCells(const RefRows &rownrs, const Slicer &slicer, Array< Float > &data)
Get a section of some arrays in the column.
virtual void create64(rownr_t initialNrrow)
Initialize the object for a new table.
void scaleOnGet(Float scale, Float offset, Array< Float > &array, const Array< Short > &target)
Scale and/or offset target to array.
void makeScaleOffset(Float &scale, Float &offset, Float minVal, Float maxVal) const
Make scale and offset from the minimum and maximum of the array data.
virtual String dataManagerType() const
Return the type name of the engine (i.e.
Array< Short > buffer_p
CompressFloat(const Record &spec)
Construct from a record specification as created by getmanagerSpec().
Abstract base class for a data manager.
Definition: DataManager.h:221
String: the storage and methods of handling collections of characters.
Definition: String.h:225
this file contains all the compiler specific defines
Definition: mainpage.dox:28
TableExprNode array(const TableExprNode &values, const TableExprNodeSet &shape)
Create an array of the given shape and fill it with the values.
Definition: ExprNode.h:1929
float Float
Definition: aipstype.h:54
bool Bool
Define the standard types used by Casacore.
Definition: aipstype.h:42
const Bool True
Definition: aipstype.h:43
uInt64 rownr_t
Define the type of a row number in a table.
Definition: aipsxtype.h:46