1 | // $Id: concepts.doxygen 2504 2011-06-29 19:26:47Z peter $ |
---|
2 | // |
---|
3 | // Copyright (C) 2008 Jari Häkkinen, Peter Johansson, Markus Ringnér |
---|
4 | // Copyright (C) 2009, 2010, 2011 Peter Johansson |
---|
5 | // |
---|
6 | // This file is part of the yat library, http://dev.thep.lu.se/yat |
---|
7 | // |
---|
8 | // The yat library is free software; you can redistribute it and/or |
---|
9 | // modify it under the terms of the GNU General Public License as |
---|
10 | // published by the Free Software Foundation; either version 3 of the |
---|
11 | // License, or (at your option) any later version. |
---|
12 | // |
---|
13 | // The yat library is distributed in the hope that it will be useful, |
---|
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
---|
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
---|
16 | // General Public License for more details. |
---|
17 | // |
---|
18 | // You should have received a copy of the GNU General Public License |
---|
19 | // along with yat. If not, see <http://www.gnu.org/licenses/>. |
---|
20 | |
---|
21 | |
---|
22 | /** |
---|
23 | \page Concepts Concepts |
---|
24 | |
---|
25 | This page lists all the C++ concepts in the yat project. |
---|
26 | |
---|
27 | - \subpage concept_container_2d |
---|
28 | - \subpage concept_data_iterator |
---|
29 | - \subpage concept_distance |
---|
30 | - \subpage concept_mutable_container_2d |
---|
31 | - \subpage concept_neighbor_weighting |
---|
32 | - \subpage concept_weighted_iterator |
---|
33 | */ |
---|
34 | |
---|
35 | |
---|
36 | /** |
---|
37 | \page concept_container_2d Container2D |
---|
38 | |
---|
39 | \section Description |
---|
40 | |
---|
41 | \ref concept_container_2d is a <a |
---|
42 | href="http://www.sgi.com/tech/stl/Container.html">Container</a> that |
---|
43 | stores elements in a two-dimensional array (columns and rows). It |
---|
44 | provides element access of a specific row and column, as well |
---|
45 | as iterators that can be used to iterate over a specific column or |
---|
46 | row. |
---|
47 | |
---|
48 | \section Requirements |
---|
49 | |
---|
50 | A \ref concept_container_2d provides the following: |
---|
51 | |
---|
52 | \subsection Types |
---|
53 | |
---|
54 | <table cellspacing=0 border=1> |
---|
55 | <tr><td>Value type</td><td><tt>X::value_type</tt></td> |
---|
56 | <td>Type of element stored in Container.</td> |
---|
57 | </tr> |
---|
58 | <tr><td>Const reference type</td><td><tt>X::const_reference</tt></td> |
---|
59 | <td>A type that behaves as const reference to the \ref |
---|
60 | concept_container_2d 's value type.</td> |
---|
61 | </tr> |
---|
62 | <tr> |
---|
63 | <td>Const iterator type</td> |
---|
64 | <td><tt>X::const_iterator</tt></td> |
---|
65 | <td> |
---|
66 | A read-only iterator that can be used to iterate over the entire \ref |
---|
67 | concept_container_2d. Typically the iterator iterates along a |
---|
68 | row, and when the end of one row is reached it jumps to the |
---|
69 | beginning of the next row. |
---|
70 | </td> |
---|
71 | </tr> |
---|
72 | <tr> |
---|
73 | <td>Const column iterator type</td> |
---|
74 | <td><tt>X::const_column_iterator</tt></td> |
---|
75 | <td> |
---|
76 | A read-only iterator that can be used to examine the elements in one |
---|
77 | column of the \ref concept_container_2d. |
---|
78 | </td> |
---|
79 | </tr> |
---|
80 | <tr> |
---|
81 | <td>Const row iterator type</td> |
---|
82 | <td><tt>X::const_row_iterator</tt></td> |
---|
83 | <td> |
---|
84 | A read-only iterator that can be used to examine the elements in one |
---|
85 | row of the \ref concept_container_2d. |
---|
86 | </td> |
---|
87 | </tr> |
---|
88 | </table> |
---|
89 | |
---|
90 | \subsection public_functions Public Functions |
---|
91 | |
---|
92 | <table cellspacing=0 border=1> |
---|
93 | <tr> |
---|
94 | <th>Name</th><th>Expression</th><th>Precondition</th><th>Return type</th> |
---|
95 | <th>Postcondition</th> |
---|
96 | </tr> |
---|
97 | <tr> |
---|
98 | <td>Beginning of range</td> |
---|
99 | <td><tt>a.begin()</tt></td> |
---|
100 | <td> </td> |
---|
101 | <td><tt>const_iterator</tt></td> |
---|
102 | <td> </td> |
---|
103 | </tr> |
---|
104 | <tr> |
---|
105 | <td>Beginning of column</td> |
---|
106 | <td><tt>a.begin_column(size_t column)</tt></td> |
---|
107 | <td><tt>0 <= column < a.columns()</tt></td> |
---|
108 | <td><tt>const_column_iterator</tt></td> |
---|
109 | <td> </td> |
---|
110 | </tr> |
---|
111 | <tr> |
---|
112 | <td>Beginning of row</td> |
---|
113 | <td><tt>a.begin_row(size_t row)</tt></td> |
---|
114 | <td><tt>0 <= row < a.rows()</tt></td> |
---|
115 | <td><tt>const_row_iterator</tt></td> |
---|
116 | <td> </td> |
---|
117 | </tr> |
---|
118 | <tr> |
---|
119 | <td>End of range</td> |
---|
120 | <td><tt>a.end()</tt></td> |
---|
121 | <td> </td> |
---|
122 | <td><tt>const_iterator</tt></td> |
---|
123 | <td> </td> |
---|
124 | </tr> |
---|
125 | <tr> |
---|
126 | <td>End of column</td> |
---|
127 | <td><tt>a.end_column(size_t column)</tt></td> |
---|
128 | <td><tt>0 <= column < a.columns()</tt></td> |
---|
129 | <td><tt>const_column_iterator</tt></td> |
---|
130 | <td> </td> |
---|
131 | </tr> |
---|
132 | <tr> |
---|
133 | <td>End of row</td> |
---|
134 | <td><tt>a.end_row(size_t row)</tt></td> |
---|
135 | <td><tt>0 <= row < a.rows()</tt></td> |
---|
136 | <td><tt>const_row_iterator</tt></td> |
---|
137 | <td> </td> |
---|
138 | </tr> |
---|
139 | <tr> |
---|
140 | <td>Columns</td> |
---|
141 | <td><tt>a.columns()</tt></td> |
---|
142 | <td> </td> |
---|
143 | <td><tt>size_t</tt></td> |
---|
144 | <td> </td> |
---|
145 | </tr> |
---|
146 | <tr> |
---|
147 | <td>Rows</td> |
---|
148 | <td><tt>a.rows()</tt></td> |
---|
149 | <td> </td> |
---|
150 | <td><tt>size_t</tt></td> |
---|
151 | <td> </td> |
---|
152 | </tr> |
---|
153 | <tr> |
---|
154 | <td>Element Access</td> |
---|
155 | <td><tt>a(size_t row, size_t column)</tt></td> |
---|
156 | <td><tt>0 <= row < a.rows()</tt> and |
---|
157 | <tt>0 <= column < a.columns()</tt></td> |
---|
158 | <td><tt>const_reference</tt></td> |
---|
159 | <td> </td> |
---|
160 | </tr> |
---|
161 | </table> |
---|
162 | |
---|
163 | \section Implementations |
---|
164 | |
---|
165 | Examples of concept \ref concept_container_2d include: |
---|
166 | - theplu::yat::classifier::MatrixLookup, |
---|
167 | - theplu::yat::classifier::MatrixLookupWeighted |
---|
168 | - theplu::yat::classifier::KernelLookup. |
---|
169 | |
---|
170 | */ |
---|
171 | |
---|
172 | /** |
---|
173 | \page concept_mutable_container_2d Mutable Container2D |
---|
174 | |
---|
175 | \section Description |
---|
176 | |
---|
177 | \ref concept_mutable_container_2d is a \ref concept_container_2d that |
---|
178 | also provides non-const access to its elements. |
---|
179 | |
---|
180 | \section Requirements |
---|
181 | |
---|
182 | In addition to the requirements defined in \ref concept_container_2d, |
---|
183 | a \ref concept_mutable_container_2d also provides the following: |
---|
184 | |
---|
185 | \subsection Types |
---|
186 | |
---|
187 | <table cellspacing=0 border=1> |
---|
188 | <tr><td>Reference type</td><td><tt>X::reference</tt></td> |
---|
189 | <td>A type that behaves as reference to the \ref |
---|
190 | concept_mutable_container_2d 's value type.</td> |
---|
191 | </tr> |
---|
192 | <tr> |
---|
193 | <td>Iterator type</td> |
---|
194 | <td><tt>X::iterator</tt></td> |
---|
195 | <td> |
---|
196 | |
---|
197 | A mutable iterator similar to Const iterator type, which can be used to |
---|
198 | iterate over the \ref concept_mutable_container_2d (and modify the |
---|
199 | elements). Typically the iterator iterates along a row, and when the |
---|
200 | end of one row is reached it jumps to the beginning of the next row. |
---|
201 | |
---|
202 | </td> |
---|
203 | </tr> |
---|
204 | <tr> |
---|
205 | <td>Column iterator type</td> |
---|
206 | <td><tt>X::column_iterator</tt></td> |
---|
207 | <td> |
---|
208 | A mutable iterator that can be used to modify the elements in one |
---|
209 | column of the \ref concept_mutable_container_2d. |
---|
210 | </td> |
---|
211 | </tr> |
---|
212 | <tr> |
---|
213 | <td>Row iterator type</td> |
---|
214 | <td><tt>X::row_iterator</tt></td> |
---|
215 | <td> |
---|
216 | A mutable iterator that can be used to modify the elements in one |
---|
217 | row of the \ref concept_mutable_container_2d. |
---|
218 | </td> |
---|
219 | </tr> |
---|
220 | </table> |
---|
221 | |
---|
222 | \subsection public_functions Public Functions |
---|
223 | |
---|
224 | <table cellspacing=0 border=1> |
---|
225 | <tr> |
---|
226 | <th>Name</th><th>Expression</th><th>Precondition</th><th>Return type</th> |
---|
227 | <th>Postcondition</th> |
---|
228 | </tr> |
---|
229 | <tr> |
---|
230 | <td>Beginning of range</td> |
---|
231 | <td><tt>a.begin()</tt></td> |
---|
232 | <td> </td> |
---|
233 | <td><tt>iterator</tt></td> |
---|
234 | <td><tt>iterator</tt> is derefenceable, unless <tt>a</tt> is empty</td> |
---|
235 | </tr> |
---|
236 | <tr> |
---|
237 | <td>Beginning of column</td> |
---|
238 | <td><tt>a.begin_column(size_t column)</tt></td> |
---|
239 | <td><tt>0 <= column < a.columns()</tt></td> |
---|
240 | <td><tt>column_iterator</tt></td> |
---|
241 | <td><tt>column_iterator</tt> is derefenceable, unless <tt>a</tt> is empty</td> |
---|
242 | </tr> |
---|
243 | <tr> |
---|
244 | <td>Beginning of row</td> |
---|
245 | <td><tt>a.begin_row(size_t row)</tt></td> |
---|
246 | <td><tt>0 <= row < a.rows()</tt></td> |
---|
247 | <td><tt>row_iterator</tt></td> |
---|
248 | <td><tt>row_iterator</tt> is derefenceable, unless <tt>a</tt> is empty</td> |
---|
249 | </tr> |
---|
250 | <tr> |
---|
251 | <td>End of range</td> |
---|
252 | <td><tt>a.end()</tt></td> |
---|
253 | <td> </td> |
---|
254 | <td><tt>iterator</tt></td> |
---|
255 | <td> </td> |
---|
256 | </tr> |
---|
257 | <tr> |
---|
258 | <td>End of column</td> |
---|
259 | <td><tt>a.end_column(size_t column)</tt></td> |
---|
260 | <td><tt>column<a.columns()</tt></td> |
---|
261 | <td><tt>column_iterator</tt></td> |
---|
262 | <td> </td> |
---|
263 | </tr> |
---|
264 | <tr> |
---|
265 | <td>End of row</td> |
---|
266 | <td><tt>a.end_row(size_t row)</tt></td> |
---|
267 | <td><tt>row<a.rows()</tt></td> |
---|
268 | <td><tt>row_iterator</tt></td> |
---|
269 | <td> </td> |
---|
270 | </tr> |
---|
271 | <tr> |
---|
272 | <td>Element Access</td> |
---|
273 | <td><tt>a(size_t row, size_t column)</tt></td> |
---|
274 | <td><tt>0 <= row < a.rows()</tt> and |
---|
275 | <tt>0 <= column < a.columns()</tt></td> |
---|
276 | <td><tt>reference</tt></td> |
---|
277 | <td> </td> |
---|
278 | </tr> |
---|
279 | </table> |
---|
280 | |
---|
281 | \section Implementations |
---|
282 | |
---|
283 | Examples of concept \ref concept_mutable_container_2d include: |
---|
284 | - theplu::yat::utility::Matrix, |
---|
285 | - theplu::yat::utility::MatrixWeighted |
---|
286 | |
---|
287 | */ |
---|
288 | |
---|
289 | /** |
---|
290 | \page concept_distance Distance |
---|
291 | |
---|
292 | \section Description |
---|
293 | |
---|
294 | \ref concept_distance is a concept for classes implementing different |
---|
295 | alternatives to calculate the distance between two points. |
---|
296 | |
---|
297 | \section Requirements |
---|
298 | |
---|
299 | Classes modelling the concept \ref concept_distance should have a copy |
---|
300 | constructor |
---|
301 | |
---|
302 | \verbatim |
---|
303 | Distance(const Distance& d); |
---|
304 | \endverbatim |
---|
305 | |
---|
306 | and also implement the following public function: |
---|
307 | |
---|
308 | \verbatim |
---|
309 | template<typename Iter1, typename Iter2> |
---|
310 | double operator() (Iter1 beg1, Iter1 end1, Iter2 beg2) const |
---|
311 | \endverbatim |
---|
312 | |
---|
313 | This function should calculate and return the distance between |
---|
314 | elements of two ranges. The first range is given by [\a beg1, \a end1) |
---|
315 | and the second range starts with \a beg2 and has the same length as |
---|
316 | the first range. The function should support iterators of the category |
---|
317 | std::forward_iterator. The function should provide both a fast |
---|
318 | calculation for unweighted iterators and a calculation for weighted |
---|
319 | iterators. The latter correspond to the case where elements in a range |
---|
320 | have both a value and a weight. The selection between unweighted and |
---|
321 | weighted implementations should utilize |
---|
322 | theplu::yat::utility::unweighted_iterator_tag and |
---|
323 | theplu::yat::utility::weighted_iterator_tag. Moreover |
---|
324 | theplu::yat::utility::weighted_if_any2 should be utilized to provide a |
---|
325 | weighted implementation if any of the two ranges is weighted, and an |
---|
326 | unweighted implementation when both ranges are unweighted. |
---|
327 | |
---|
328 | \section Implementations |
---|
329 | |
---|
330 | Examples of classes modelling the concept \ref concept_distance |
---|
331 | include theplu::yat::statistics::PearsonDistance and |
---|
332 | theplu::yat::statistics::EuclideanDistance. |
---|
333 | |
---|
334 | \see \ref weighted_distance |
---|
335 | |
---|
336 | */ |
---|
337 | |
---|
338 | /** |
---|
339 | \page concept_neighbor_weighting Neighbor Weighting Method |
---|
340 | |
---|
341 | \section Description |
---|
342 | |
---|
343 | \ref concept_neighbor_weighting is a concept used in connection with |
---|
344 | theplu::yat::classifier::KNN - classes used as the template argument |
---|
345 | NeighborWeighting should implement this concept. |
---|
346 | |
---|
347 | \section Requirements |
---|
348 | |
---|
349 | Classes modelling the concept \ref concept_neighbor_weighting should |
---|
350 | be DefaultConstructible and Assignable as well as |
---|
351 | implement the following public function: |
---|
352 | |
---|
353 | \verbatim |
---|
354 | void operator()(const utility::VectorBase& distance, |
---|
355 | const std::vector<size_t>& k_sorted, |
---|
356 | const Target& target, |
---|
357 | utility::VectorMutable& prediction) const |
---|
358 | \endverbatim |
---|
359 | |
---|
360 | For a test sample, this function should calculate a total vote |
---|
361 | (i.e. based on all k nearest neighbors) for each class. The vector \a |
---|
362 | distance contains the distances from a test sample to all training |
---|
363 | samples. The vector \a k_sorted contains the indices (for both \a |
---|
364 | distance and \a target) to the k training samples with the smallest |
---|
365 | distances to the test sample. The class for each training sample is |
---|
366 | given by \a target, which is sorted in the same sample order as \a |
---|
367 | distance. For each class the function calculates a total vote based on |
---|
368 | the the nearest neighbors of the test sample that belong to the |
---|
369 | class. The total vote for each class is stored in the vector \a |
---|
370 | prediction. The function should be implemented such that nearest |
---|
371 | neighbors with distance infinity do not vote. |
---|
372 | |
---|
373 | \section Implementations |
---|
374 | |
---|
375 | Examples of classes modelling the concept \ref |
---|
376 | concept_neighbor_weighting include |
---|
377 | theplu::yat::classifier::KNN_Uniform, |
---|
378 | theplu::yat::classifier::KNN_ReciprocalDistance and |
---|
379 | theplu::yat::classifier::KNN_ReciprocalRank. |
---|
380 | |
---|
381 | */ |
---|
382 | |
---|
383 | /** |
---|
384 | \page concept_weighted_iterator Weighted Iterator |
---|
385 | |
---|
386 | \section Description |
---|
387 | |
---|
388 | Most functionality in yat come in two versions: one optimized for |
---|
389 | speed and one weighted version allowing for missing value (see \ref |
---|
390 | weighted_statistics). For example, weighted containers such as |
---|
391 | theplu::yat::utility::MatrixWeighted and |
---|
392 | theplu::yat::classifier::MatrixLookupWeighted allow an easy way to |
---|
393 | handle missing values. Iterators that iterate over such weighted |
---|
394 | containers are by definition \ref concept_weighted_iterator. This |
---|
395 | concept is orthogonal against other iterator concepts such as Random |
---|
396 | Access Iterator. |
---|
397 | |
---|
398 | \section Requirements |
---|
399 | |
---|
400 | When implementing a new iterator that may be a \ref |
---|
401 | concept_weighted_iterator, there are a few things to concider. |
---|
402 | |
---|
403 | \subsection weighted_iterator_traits |
---|
404 | |
---|
405 | To decide whether an iterator is weighted, there exists a |
---|
406 | meta-function |
---|
407 | theplu::yat::utility::weighted_iterator_traits<Iterator>::type that |
---|
408 | will return either theplu::yat::utility::weighted_iterator_tag or |
---|
409 | theplu::yat::utility::unweighted_iterator_tag. The default |
---|
410 | implementation of this meta-function works in most cases, including on |
---|
411 | all std::iterators, but if you implement a new iterator make sure it |
---|
412 | behaves as you desire, or you need to create a specialization. |
---|
413 | |
---|
414 | \subsection iterator_traits |
---|
415 | |
---|
416 | Sometimes it is useful to have unweighted iterators behaving as though |
---|
417 | they were weighted. For instance, |
---|
418 | theplu::yat::statistics::EuclideanDistance calculates the distance |
---|
419 | between two ranges. If both ranges are unweighted the unweighted |
---|
420 | version is used, and when any of the two ranges is weighted the |
---|
421 | weighted version kicks in. In order to make this work also when |
---|
422 | comparing weighted and unweighted ranges, there must a mechanism to |
---|
423 | let the unweighted iterator behave as though it were weighted. |
---|
424 | |
---|
425 | This can be accomplished through |
---|
426 | theplu::yat::utility::iterator_traits, which enables access to data |
---|
427 | value as well as to weight value. For unweighted iterators the weight |
---|
428 | value is always equal to 1.0 and is not mutable. The default |
---|
429 | implementation works for most iterators including all unweighted, but |
---|
430 | if you implement a new weighted iterator you need to check that the |
---|
431 | default implementation will work for you (see class |
---|
432 | documentation). Otherwise, you will need to implement a |
---|
433 | specialization. Note that the default implementation requires that, if |
---|
434 | \c iterator is a weighted iterator, its \c reference must have |
---|
435 | member functions data() and weight(). This should not be a problem as |
---|
436 | long as \c reference is theplu::yat::utility::DataWeight or |
---|
437 | theplu::yat::utility::DataWeightProxy, but could potentially be a |
---|
438 | problem when creating weighted iterators with other \c reference. |
---|
439 | |
---|
440 | */ |
---|
441 | |
---|
442 | /** |
---|
443 | \page concept_data_iterator Data Iterator |
---|
444 | |
---|
445 | \section Description |
---|
446 | |
---|
447 | \ref concept_data_iterator is an iterator that is either: |
---|
448 | |
---|
449 | - a \ref concept_weighted_iterator with value type convertible to |
---|
450 | theplu::yat::utility::DataWeight. |
---|
451 | - an unweighted iterator with value type convertible to \c double. |
---|
452 | |
---|
453 | \section Implementations |
---|
454 | |
---|
455 | Examples of concept \ref concept_data_iterator include: |
---|
456 | - theplu::yat::utility::Matrix::iterator, |
---|
457 | - theplu::yat::utility::MatrixWeighted::iterator, |
---|
458 | - theplu::yat::classifier::MatrixLookup::const_iterator, |
---|
459 | - theplu::yat::classifier::MatrixLookupWeighted::const_iterator |
---|
460 | */ |
---|