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conncomp.cpp
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129 lines (107 loc) · 3.07 KB
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/*
* This file is part of the GreasePad distribution (https://github.com/FraunhoferIOSB/GreasePad).
* Copyright (c) 2022 Jochen Meidow, Fraunhofer IOSB
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "conncomp.h"
#include "global.h"
namespace Graph {
ConnComp::ConnComp( const SparseMatrix<int, ColMajor> &BB)
{
// qDebug() << Q_FUNC_INFO;
assert( BB.rows()==BB.cols() );
// Q_ASSERT( BB.rows()==BB.cols() );
const Index V = BB.rows(); // number of vertices
m_visited.setConstant( V,false);
m_comp.setConstant( V,-1);
int num_connected_components = 0;
for ( Index v=0; v<V; v++ ) {
if ( !m_visited(v) ) {
dfs( BB, num_connected_components++, v );
}
}
}
VectorXi ConnComp::head(const int n) const
{
assert( n>=0 );
if ( n==0) {
return VectorXi(0);
}
return m_comp.head(n);
}
VectorXi ConnComp::tail( const int n) const
{
assert( n>=0 );
if ( n==0) {
return VectorXi(0);
}
return m_comp.tail(n);
}
/*! Label of i-th element */
int ConnComp::label( const Index i) const
{
assert( i>=0 && i<m_comp.size() ) ;
return m_comp(i);
}
VectorXi ConnComp::mapHead( const int cc, const int n) const
{
// (1) Vector length: How many elements with value cc? .........
int sz=0;
for ( int s=0; s<n; s++ ) {
if ( m_comp(s)==cc ) {
sz++;
}
}
// (2) Linear indices of these elements ........................
VectorXi map_(sz);
for ( int k=0, s=0; s<n; s++ ) {
if ( m_comp(s)==cc ) {
map_( k++ ) = s;
}
}
return map_;
}
VectorXi ConnComp::mapTail( const int cc, const int n) const
{
// (1) Vector length: How many elements with value cc? .........
int sz=0;
for ( Index s=m_comp.size()-n; s<m_comp.size(); s++ ) {
if ( m_comp(s)==cc ) {
sz++;
}
}
// (2) Linear indices of these elements ........................
VectorXi map_(sz);
Index offset = m_comp.size() -n;
for ( int k=0, s=0; s<n; s++ ) {
if ( m_comp( s+offset )==cc ) {
map_( k++ ) = s;
}
}
return map_;
}
void ConnComp::dfs( const SparseMatrix<int,ColMajor> &CC,
const int c,
const Index v)
{
m_visited(v) = true;
m_comp(v) = c;
for ( SparseMatrix<int,ColMajor>::InnerIterator it(CC,v); it; ++it) {
if ( !m_visited(it.index()) ) {
dfs( CC, c, it.row() );
}
}
}
} // namespace Graph