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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>
36 
37 
38 namespace 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 (uInt i=0, i<10; i++) { // table will have 10 rows
133 // table.addRow();
134 // data.put (i, someArray)
135 // }
136 // </srcblock>
137 // </example>
138 
139 class CompressFloat : public BaseMappedArrayEngine<Float, Short>
140 {
141 public:
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.
173  ~CompressFloat();
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.
186  static String className();
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 
192 private:
193  // Copy constructor is only used by clone().
194  // (so it is made private).
195  CompressFloat (const CompressFloat&);
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 create (uInt 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 (uInt startRow, uInt nrrow);
221 
222  // Get an array in the given row.
223  // This will scale and offset from the underlying array.
224  virtual void getArray (uInt 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 (uInt 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 (uInt rownr, const Slicer& slicer,
233  Array<Float>& array);
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 (uInt 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.
242  virtual void getArrayColumn (Array<Float>& 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,
283  Array<Float>& array,
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.
297  void scaleColumnOnGet (Array<Float>& array,
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.
304  void scaleColumnOnPut (const Array<Float>& array,
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 (uInt rownr);
321 
322  // Get the offset value for this row.
323  Float getOffset (uInt 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 (uInt 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 (uInt rownr, const Slicer& slicer,
344  Array<Float>& fullArray,
345  const Array<Float>& partArray,
346  Float minVal, Float maxVal);
347 
348 public:
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.
355  static DataManager* makeObject (const String& dataManagerType,
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
virtual DataManager * clone() const
Clone the engine object.
void putFullPart(uInt 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.
Array< Short > buffer_p
ScalarColumn< Float > * scaleColumn_p
virtual void getColumnSliceCells(const RefRows &rownrs, const Slicer &slicer, Array< Float > &data)
Get a section of some arrays in the column.
~CompressFloat()
Destructor is mandatory.
TableExprNode array(const TableExprNode &values, const TableExprNodeSet &shape)
Create an array of the given shape and fill it with the values.
Definition: ExprNode.h:1886
virtual void create(uInt initialNrrow)
Initialize the object for a new table.
Templated virtual column engine for a table array of any type.
CompressFloat & operator=(const CompressFloat &)
Assignment is not needed and therefore forbidden (so it is made private and not implemented).
void scaleOnPut(Float scale, Float offset, const Array< Float > &array, Array< Short > &target)
Scale and/or offset array to target.
virtual String dataManagerName() const
Get the name given to the engine (is the virtual column name).
virtual void putArrayColumn(const Array< Float > &array)
Put an entire column.
virtual void putArray(uInt rownr, const Array< Float > &array)
Put an array in the given row.
Virtual column engine to scale a table float array.
virtual void putColumnSlice(const Slicer &slicer, const Array< Float > &array)
Put a section of all arrays in the column.
static void registerClass()
Register the class name and the static makeObject &quot;constructor&quot;.
virtual void reopenRW()
Reopen the engine for read/write access.
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...
ABSTRACT CLASSES Deliberately vague to be general enough to allow for many different types of data
Definition: PlotData.h:48
void findMinMax(Float &minVal, Float &maxVal, const Array< Float > &array) const
Find minimum and maximum from the array data.
ScalarColumn< Float > * offsetColumn_p
virtual void getArray(uInt rownr, Array< Float > &array)
Get an array in the given row.
virtual String dataManagerType() const
Return the type name of the engine (i.e.
void putPart(uInt 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.
void scaleColumnOnPut(const Array< Float > &array, Array< Short > &target)
Scale and/or offset array to target for the entire column.
virtual void getColumnSlice(const Slicer &slicer, Array< Float > &array)
Get a section of all arrays in the column.
Class holding the row numbers in a RefTable.
Definition: RefRows.h:85
virtual void addRowInit(uInt startRow, uInt nrrow)
Add rows to the table.
static DataManager * makeObject(const String &dataManagerType, const Record &spec)
Define the &quot;constructor&quot; to construct this engine when a table is read back.
A hierarchical collection of named fields of various types.
Definition: Record.h:180
bool Bool
Define the standard types used by Casacore.
Definition: aipstype.h:42
virtual void putColumnSliceCells(const RefRows &rownrs, const Slicer &slicer, const Array< Float > &data)
Put into a section of some arrays in the column.
virtual void getArrayColumnCells(const RefRows &rownrs, Array< Float > &data)
Get some array values in the column.
float Float
Definition: aipstype.h:54
virtual void putSlice(uInt rownr, const Slicer &slicer, const Array< Float > &array)
Put into a section of the 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...
virtual void putArrayColumnCells(const RefRows &rownrs, const Array< Float > &data)
Put some array values in the column.
Specify which elements to extract from an n-dimensional array.
Definition: Slicer.h:289
Float getScale(uInt rownr)
Get the scale value for this row.
virtual void getArrayColumn(Array< Float > &array)
Get an entire column.
virtual Record dataManagerSpec() const
Record a record containing data manager specifications.
void scaleOnGet(Float scale, Float offset, Array< Float > &array, const Array< Short > &target)
Scale and/or offset target to array.
Abstract base class for a data manager.
Definition: DataManager.h:224
void makeScaleOffset(Float &scale, Float &offset, Float minVal, Float maxVal) const
Make scale and offset from the minimum and maximum of the array data.
static String className()
Return the name of the class.
String: the storage and methods of handling collections of characters.
Definition: String.h:223
virtual void getSlice(uInt rownr, const Slicer &slicer, Array< Float > &array)
Get a section of the array in the given row.
void scaleColumnOnGet(Array< Float > &array, const Array< Short > &target)
Scale and/or offset target to array for the entire column.
const Bool True
Definition: aipstype.h:43
unsigned int uInt
Definition: aipstype.h:51
Float getOffset(uInt rownr)
Get the offset value for this row.
#define casacore
&lt;X11/Intrinsic.h&gt; #defines true, false, casacore::Bool, and String.
Definition: X11Intrinsic.h:42