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36 * \brief API for neighborhood searching for analysis.
38 * The main part of the API is the class gmx::AnalysisNeighborhood.
39 * See the class documentation for usage.
41 * The classes within this file can be used independently of the other parts
43 * The library also uses the classes internally.
45 * \author Teemu Murtola <teemu.murtola@gmail.com>
47 * \ingroup module_selection
49 #ifndef GMX_SELECTION_NBSEARCH_H
50 #define GMX_SELECTION_NBSEARCH_H
52 #include <boost/shared_ptr.hpp>
54 #include "../legacyheaders/typedefs.h"
55 #include "../utility/common.h"
56 #include "../utility/gmxassert.h"
58 #include "indexutil.h"
67 class AnalysisNeighborhoodSearchImpl;
68 class AnalysisNeighborhoodPairSearchImpl;
71 class AnalysisNeighborhoodSearch;
72 class AnalysisNeighborhoodPairSearch;
75 * Neighborhood searching for analysis tools.
77 * This class implements neighborhood searching routines for analysis tools.
78 * The emphasis is in flexibility and ease of use; one main driver is to have
79 * a common implementation of grid-based searching to avoid replicating this in
80 * multiple tools (and to make more tools take advantage of the significant
81 * performance improvement this allows).
83 * To use the search, create an object of this type, call setCutoff() to
84 * initialize it, and then repeatedly call initSearch() to start a search with
85 * different sets of reference positions. For each set of reference positions,
86 * use methods in the returned AnalysisNeighborhoodSearch to find the reference
87 * positions that are within the given cutoff from a provided position.
89 * initSearch() is thread-safe and can be called from multiple threads. Each
90 * call returns a different instance of the search object that can be used
91 * independently of the others. However, the returned search objects can only
92 * be used within a single thread. It is also possible to create multiple
93 * concurrent searches within a single thread.
96 * Support for exclusions.
97 * The 4.5/4.6 C API had very low-level support for exclusions, which was not
98 * very convenient to use, and hadn't been tested much. The internal code that
99 * it used to do the exclusion during the search itself is still there, but it
100 * needs more thought on what would be a convenient way to initialize it.
101 * Can be implemented once there is need for it in some calling code.
104 * \ingroup module_selection
106 class AnalysisNeighborhood
109 //! Searching algorithm to use.
112 //! Select algorithm based on heuristic efficiency considerations.
113 eSearchMode_Automatic,
114 //! Use a simple loop over all pairs.
116 //! Use grid-based searching whenever possible.
120 //! Creates an uninitialized neighborhood search.
121 AnalysisNeighborhood();
122 ~AnalysisNeighborhood();
125 * Set cutoff distance for the neighborhood searching.
127 * \param[in] cutoff Cutoff distance for the search
128 * (<=0 stands for no cutoff).
130 * Currently, can only be called before the first call to initSearch().
131 * If this method is not called, no cutoff is used in the searches.
135 void setCutoff(real cutoff);
137 * Sets the algorithm to use for searching.
139 * \param[in] mode Search mode to use.
141 * Note that if \p mode is \ref eSearchMode_Grid, it is still only a
142 * suggestion: grid-based searching may not be possible with the
143 * provided input, in which case a simple search is still used.
144 * This is mainly useful for testing purposes to force a mode.
148 void setMode(SearchMode mode);
149 //! Returns the currently active search mode.
150 SearchMode mode() const;
153 * Initializes neighborhood search for a set of positions.
155 * \param[in] pbc PBC information for the frame.
156 * \param[in] n Number of reference positions for the frame.
157 * \param[in] x \p n reference positions for the frame.
158 * \returns Search object that can be used to find positions from
159 * \p x within the given cutoff.
160 * \throws std::bad_alloc if out of memory.
162 AnalysisNeighborhoodSearch
163 initSearch(const t_pbc *pbc, int n, const rvec x[]);
165 * Initializes neighborhood search for a set of positions.
167 * \param[in] pbc PBC information for the frame.
168 * \param[in] p Reference positions for the frame.
169 * \returns Search object that can be used to find positions from
170 * \p p within the given cutoff.
171 * \throws std::bad_alloc if out of memory.
173 AnalysisNeighborhoodSearch
174 initSearch(const t_pbc *pbc, const gmx_ana_pos_t *p);
179 PrivateImplPointer<Impl> impl_;
183 * Value type to represent a pair of positions found in neighborhood searching.
185 * Methods in this class do not throw.
188 * \ingroup module_selection
190 class AnalysisNeighborhoodPair
193 //! Initializes an invalid pair.
194 AnalysisNeighborhoodPair() : refIndex_(-1), testIndex_(0) {}
195 //! Initializes a pair object with the given data.
196 AnalysisNeighborhoodPair(int refIndex, int testIndex)
197 : refIndex_(refIndex), testIndex_(testIndex)
202 * Whether this pair is valid.
204 * If isValid() returns false, other methods should not be called.
206 bool isValid() const { return refIndex_ >= 0; }
209 * Returns the index of the reference position in the pair.
211 * This index is always the index into the position array provided to
212 * AnalysisNeighborhood::initSearch().
216 GMX_ASSERT(isValid(), "Accessing invalid object");
220 * Returns the index of the test position in the pair.
222 * The contents of this index depends on the context (method call) that
224 * If there was no array in the call, this index is zero.
226 int testIndex() const
228 GMX_ASSERT(isValid(), "Accessing invalid object");
238 * Initialized neighborhood search with a fixed set of reference positions.
240 * An instance of this class is obtained through
241 * AnalysisNeighborhood::initSearch(), and can be used to do multiple searches
242 * against the provided set of reference positions.
243 * Currently, it is not possible to call startPairSearch() while a previous
244 * AnalysisNeighborhoodPairSearch object obtained from startPairSearch() of the
245 * same instance still exists.
247 * This class works like a pointer: copies of it point to the same search.
248 * In general, avoid creating copies, and only use the copy/assignment support
249 * for moving the variable around. With C++11, this class would best be
252 * Methods in this class do not throw.
255 * Make it such that reset() is not necessary to call in code that repeatedly
256 * assigns the result of AnalysisNeighborhood::initSearch() to the same
257 * variable (see sm_distance.cpp).
260 * Consider merging nearestPoint() and minimumDistance() by adding the distance
261 * to AnalysisNeighborhoodPair.
264 * \ingroup module_selection
266 class AnalysisNeighborhoodSearch
270 * Internal short-hand type for a pointer to the implementation class.
272 * shared_ptr is used here to automatically keep a reference count to
273 * track whether an implementation class is still used outside the
274 * AnalysisNeighborhood object. Ownership currently always stays with
275 * AnalysisNeighborhood; it always keeps one instance of the pointer.
277 typedef boost::shared_ptr<internal::AnalysisNeighborhoodSearchImpl>
281 * Initializes an invalid search.
283 * Such an object cannot be used for searching. It needs to be
284 * assigned a value from AnalysisNeighborhood::initSearch() before it
285 * can be used. Provided to allow declaring a variable to hold the
286 * search before calling AnalysisNeighborhood::initSearch().
288 AnalysisNeighborhoodSearch();
290 * Internally initialize the search.
292 * Used to implement AnalysisNeighborhood::initSearch().
293 * Cannot be called from user code.
295 explicit AnalysisNeighborhoodSearch(const ImplPointer &impl);
298 * Clears this search.
300 * Equivalent to \c "*this = AnalysisNeighborhoodSearch();".
301 * Currently, this is necessary to avoid unnecessary memory allocation
302 * if the previous search variable is still in scope when you want to
303 * call AnalysisNeighborhood::initSearch() again.
308 * Returns the searching algorithm that this search is using.
310 * The return value is never AnalysisNeighborhood::eSearchMode_Automatic.
312 AnalysisNeighborhood::SearchMode mode() const;
315 * Check whether a point is within a neighborhood.
317 * \param[in] x Test position.
318 * \returns true if the test position is within the cutoff of any
319 * reference position.
321 bool isWithin(const rvec x) const;
323 * Check whether a point is within a neighborhood.
325 * \param[in] p Test positions.
326 * \param[in] i Use the i'th position in \p p for testing.
327 * \returns true if the test position is within the cutoff of any
328 * reference position.
330 bool isWithin(const gmx_ana_pos_t *p, int i) const;
332 * Calculates the minimum distance from the reference points.
334 * \param[in] x Test position.
335 * \returns The distance to the nearest reference position, or the
336 * cutoff value if there are no reference positions within the
339 real minimumDistance(const rvec x) const;
341 * Calculates the minimum distance from the reference points.
343 * \param[in] p Test positions.
344 * \param[in] i Use the i'th position in \p p for testing.
345 * \returns The distance to the nearest reference position, or the
346 * cutoff value if there are no reference positions within the
349 real minimumDistance(const gmx_ana_pos_t *p, int i) const;
351 * Finds the closest reference point.
353 * \param[in] x Test position.
354 * \returns The reference index identifies the reference position
355 * that is closest to the test position.
356 * The test index is always zero. The returned pair is invalid if
357 * no reference position is within the cutoff.
359 AnalysisNeighborhoodPair nearestPoint(const rvec x) const;
361 * Finds the closest reference point.
363 * \param[in] p Test positions.
364 * \param[in] i Use the i'th position in \p p for testing.
365 * \returns The reference index identifies the reference position
366 * that is closest to the test position.
367 * The test index is always \p i. The returned pair is invalid if
368 * no reference position is within the cutoff.
370 AnalysisNeighborhoodPair nearestPoint(const gmx_ana_pos_t *p, int i) const;
373 * Start a search to find reference positions within a cutoff.
375 * \param[in] x Test position to search the neighbors for.
376 * \returns Initialized search object to loop through all reference
377 * positions within the configured cutoff.
379 * In the AnalysisNeighborhoodPair objects returned by the search, the
380 * test index is always zero.
382 AnalysisNeighborhoodPairSearch startPairSearch(const rvec x);
384 * Start a search to find reference positions within a cutoff.
386 * \param[in] p Test positions.
387 * \param[in] i Use the i'th position in \p p for testing.
388 * \returns Initialized search object to loop through all reference
389 * positions within the configured cutoff.
391 * In the AnalysisNeighborhoodPair objects returned by the search, the
392 * test index is always \p i.
394 AnalysisNeighborhoodPairSearch startPairSearch(const gmx_ana_pos_t *p, int i);
401 * Initialized neighborhood pair search with a fixed set of positions.
403 * This class is used to loop through pairs of neighbors within the cutoff
404 * provided to AnalysisNeighborhood. The following code demonstrates its use:
406 gmx::AnalysisNeighborhood nb;
407 nb.setCutoff(cutoff);
408 gmx::AnalysisNeighborhoodSearch search = nb.initSearch(pbc, nref, xref);
409 gmx::AnalysisNeighborhoodPairSearch pairSearch = search.startPairSearch(x);
410 gmx::AnalysisNeighborhoodPair pair;
411 while (pairSearch.findNextPair(&pair))
413 // <do something for each found pair the information in pair>
417 * It is not possible to use a single search object from multiple threads
420 * This class works like a pointer: copies of it point to the same search.
421 * In general, avoid creating copies, and only use the copy/assignment support
422 * for moving the variable around. With C++11, this class would best be
425 * Methods in this class do not throw.
428 * \ingroup module_selection
430 class AnalysisNeighborhoodPairSearch
434 * Internal short-hand type for a pointer to the implementation class.
436 * See AnalysisNeighborhoodSearch::ImplPointer for rationale of using
437 * shared_ptr and ownership semantics.
439 typedef boost::shared_ptr<internal::AnalysisNeighborhoodPairSearchImpl>
443 * Internally initialize the search.
445 * Used to implement AnalysisNeighborhoodSearch::startPairSearch().
446 * Cannot be called from user code.
448 explicit AnalysisNeighborhoodPairSearch(const ImplPointer &impl);
451 * Finds the next pair within the cutoff.
453 * \param[out] pair Information about the found pair.
454 * \returns false if there were no more pairs.
456 * If the method returns false, \p pair will be invalid.
458 * \see AnalysisNeighborhoodPair
459 * \see AnalysisNeighborhoodSearch::startPairSearch()
461 bool findNextPair(AnalysisNeighborhoodPair *pair);