1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2015 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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6 // modification, are permitted provided that the following conditions are met:
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9 // this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above copyright notice,
11 // this list of conditions and the following disclaimer in the documentation
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14 // used to endorse or promote products derived from this software without
15 // specific prior written permission.
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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27 // POSSIBILITY OF SUCH DAMAGE.
29 // Author: sameeragarwal@google.com (Sameer Agarwal)
31 #ifndef CERES_PUBLIC_ORDERED_GROUPS_H_
32 #define CERES_PUBLIC_ORDERED_GROUPS_H_
37 #include "ceres/internal/port.h"
38 #include "glog/logging.h"
42 // A class for storing and manipulating an ordered collection of
43 // groups/sets with the following semantics:
45 // Group ids are non-negative integer values. Elements are any type
46 // that can serve as a key in a map or an element of a set.
48 // An element can only belong to one group at a time. A group may
49 // contain an arbitrary number of elements.
51 // Groups are ordered by their group id.
55 // Add an element to a group. If a group with this id does not
56 // exist, one is created. This method can be called any number of
57 // times for the same element. Group ids should be non-negative
60 // Return value indicates if adding the element was a success.
61 bool AddElementToGroup(const T element, const int group) {
66 typename std::map<T, int>::const_iterator it =
67 element_to_group_.find(element);
68 if (it != element_to_group_.end()) {
69 if (it->second == group) {
70 // Element is already in the right group, nothing to do.
74 group_to_elements_[it->second].erase(element);
75 if (group_to_elements_[it->second].size() == 0) {
76 group_to_elements_.erase(it->second);
80 element_to_group_[element] = group;
81 group_to_elements_[group].insert(element);
86 group_to_elements_.clear();
87 element_to_group_.clear();
90 // Remove the element, no matter what group it is in. Return value
91 // indicates if the element was actually removed.
92 bool Remove(const T element) {
93 const int current_group = GroupId(element);
94 if (current_group < 0) {
98 group_to_elements_[current_group].erase(element);
100 if (group_to_elements_[current_group].size() == 0) {
101 // If the group is empty, then get rid of it.
102 group_to_elements_.erase(current_group);
105 element_to_group_.erase(element);
109 // Bulk remove elements. The return value indicates the number of
110 // elements successfully removed.
111 int Remove(const std::vector<T>& elements) {
112 if (NumElements() == 0 || elements.size() == 0) {
117 for (int i = 0; i < elements.size(); ++i) {
118 num_removed += Remove(elements[i]);
123 // Reverse the order of the groups in place.
125 if (NumGroups() == 0) {
129 typename std::map<int, std::set<T> >::reverse_iterator it =
130 group_to_elements_.rbegin();
131 std::map<int, std::set<T> > new_group_to_elements;
132 new_group_to_elements[it->first] = it->second;
134 int new_group_id = it->first + 1;
135 for (++it; it != group_to_elements_.rend(); ++it) {
136 for (typename std::set<T>::const_iterator element_it = it->second.begin();
137 element_it != it->second.end();
139 element_to_group_[*element_it] = new_group_id;
141 new_group_to_elements[new_group_id] = it->second;
145 group_to_elements_.swap(new_group_to_elements);
148 // Return the group id for the element. If the element is not a
149 // member of any group, return -1.
150 int GroupId(const T element) const {
151 typename std::map<T, int>::const_iterator it =
152 element_to_group_.find(element);
153 if (it == element_to_group_.end()) {
159 bool IsMember(const T element) const {
160 typename std::map<T, int>::const_iterator it =
161 element_to_group_.find(element);
162 return (it != element_to_group_.end());
165 // This function always succeeds, i.e., implicitly there exists a
166 // group for every integer.
167 int GroupSize(const int group) const {
168 typename std::map<int, std::set<T> >::const_iterator it =
169 group_to_elements_.find(group);
170 return (it == group_to_elements_.end()) ? 0 : it->second.size();
173 int NumElements() const {
174 return element_to_group_.size();
177 // Number of groups with one or more elements.
178 int NumGroups() const {
179 return group_to_elements_.size();
182 // The first group with one or more elements. Calling this when
183 // there are no groups with non-zero elements will result in a
185 int MinNonZeroGroup() const {
186 CHECK_NE(NumGroups(), 0);
187 return group_to_elements_.begin()->first;
190 const std::map<int, std::set<T> >& group_to_elements() const {
191 return group_to_elements_;
194 const std::map<T, int>& element_to_group() const {
195 return element_to_group_;
199 std::map<int, std::set<T> > group_to_elements_;
200 std::map<T, int> element_to_group_;
203 // Typedef for the most commonly used version of OrderedGroups.
204 typedef OrderedGroups<double*> ParameterBlockOrdering;
208 #endif // CERES_PUBLIC_ORDERED_GROUP_H_