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Commit 4f2aeeff authored by Vadim Pisarevsky's avatar Vadim Pisarevsky
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Merge pull request #3403 from vpisarev:moved_partition

parents 47838a4a d58cadc1
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Showing with 99 additions and 107 deletions
modules/core/include/opencv2/core/operations.hpp
View file @ 4f2aeeff
......@@ -526,6 +526,105 @@ void AlgorithmInfo::addParam(Algorithm& algo, const char* parameter, Ptr<_Tp>& v
}
/****************************************************************************************\
* Auxiliary algorithms *
\****************************************************************************************/
// This function splits the input sequence or set into one or more equivalence classes and
// returns the vector of labels - 0-based class indexes for each element.
// predicate(a,b) returns true if the two sequence elements certainly belong to the same class.
//
// The algorithm is described in "Introduction to Algorithms"
// by Cormen, Leiserson and Rivest, the chapter "Data structures for disjoint sets"
template<typename _Tp, class _EqPredicate> int
partition( const std::vector<_Tp>& _vec, std::vector<int>& labels,
_EqPredicate predicate=_EqPredicate())
{
int i, j, N = (int)_vec.size();
const _Tp* vec = &_vec[0];
const int PARENT=0;
const int RANK=1;
std::vector<int> _nodes(N*2);
int (*nodes)[2] = (int(*)[2])&_nodes[0];
// The first O(N) pass: create N single-vertex trees
for(i = 0; i < N; i++)
{
nodes[i][PARENT]=-1;
nodes[i][RANK] = 0;
}
// The main O(N^2) pass: merge connected components
for( i = 0; i < N; i++ )
{
int root = i;
// find root
while( nodes[root][PARENT] >= 0 )
root = nodes[root][PARENT];
for( j = 0; j < N; j++ )
{
if( i == j || !predicate(vec[i], vec[j]))
continue;
int root2 = j;
while( nodes[root2][PARENT] >= 0 )
root2 = nodes[root2][PARENT];
if( root2 != root )
{
// unite both trees
int rank = nodes[root][RANK], rank2 = nodes[root2][RANK];
if( rank > rank2 )
nodes[root2][PARENT] = root;
else
{
nodes[root][PARENT] = root2;
nodes[root2][RANK] += rank == rank2;
root = root2;
}
CV_Assert( nodes[root][PARENT] < 0 );
int k = j, parent;
// compress the path from node2 to root
while( (parent = nodes[k][PARENT]) >= 0 )
{
nodes[k][PARENT] = root;
k = parent;
}
// compress the path from node to root
k = i;
while( (parent = nodes[k][PARENT]) >= 0 )
{
nodes[k][PARENT] = root;
k = parent;
}
}
}
}
// Final O(N) pass: enumerate classes
labels.resize(N);
int nclasses = 0;
for( i = 0; i < N; i++ )
{
int root = i;
while( nodes[root][PARENT] >= 0 )
root = nodes[root][PARENT];
// re-use the rank as the class label
if( nodes[root][RANK] >= 0 )
nodes[root][RANK] = ~nclasses++;
labels[i] = ~nodes[root][RANK];
}
return nclasses;
}
} // cv
......
modules/core/include/opencv2/core/private.hpp
View file @ 4f2aeeff
......@@ -301,111 +301,4 @@ typedef enum CvStatus
}
CvStatus;
/****************************************************************************************\
* Auxiliary algorithms *
\****************************************************************************************/
namespace cv
{
// This function splits the input sequence or set into one or more equivalence classes and
// returns the vector of labels - 0-based class indexes for each element.
// predicate(a,b) returns true if the two sequence elements certainly belong to the same class.
//
// The algorithm is described in "Introduction to Algorithms"
// by Cormen, Leiserson and Rivest, the chapter "Data structures for disjoint sets"
template<typename _Tp, class _EqPredicate> int
partition( const std::vector<_Tp>& _vec, std::vector<int>& labels,
_EqPredicate predicate=_EqPredicate())
{
int i, j, N = (int)_vec.size();
const _Tp* vec = &_vec[0];
const int PARENT=0;
const int RANK=1;
std::vector<int> _nodes(N*2);
int (*nodes)[2] = (int(*)[2])&_nodes[0];
// The first O(N) pass: create N single-vertex trees
for(i = 0; i < N; i++)
{
nodes[i][PARENT]=-1;
nodes[i][RANK] = 0;
}
// The main O(N^2) pass: merge connected components
for( i = 0; i < N; i++ )
{
int root = i;
// find root
while( nodes[root][PARENT] >= 0 )
root = nodes[root][PARENT];
for( j = 0; j < N; j++ )
{
if( i == j || !predicate(vec[i], vec[j]))
continue;
int root2 = j;
while( nodes[root2][PARENT] >= 0 )
root2 = nodes[root2][PARENT];
if( root2 != root )
{
// unite both trees
int rank = nodes[root][RANK], rank2 = nodes[root2][RANK];
if( rank > rank2 )
nodes[root2][PARENT] = root;
else
{
nodes[root][PARENT] = root2;
nodes[root2][RANK] += rank == rank2;
root = root2;
}
CV_Assert( nodes[root][PARENT] < 0 );
int k = j, parent;
// compress the path from node2 to root
while( (parent = nodes[k][PARENT]) >= 0 )
{
nodes[k][PARENT] = root;
k = parent;
}
// compress the path from node to root
k = i;
while( (parent = nodes[k][PARENT]) >= 0 )
{
nodes[k][PARENT] = root;
k = parent;
}
}
}
}
// Final O(N) pass: enumerate classes
labels.resize(N);
int nclasses = 0;
for( i = 0; i < N; i++ )
{
int root = i;
while( nodes[root][PARENT] >= 0 )
root = nodes[root][PARENT];
// re-use the rank as the class label
if( nodes[root][RANK] >= 0 )
nodes[root][RANK] = ~nclasses++;
labels[i] = ~nodes[root][RANK];
}
return nclasses;
}
} // namespace cv
#endif // __OPENCV_CORE_PRIVATE_HPP__
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