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c0b253a69b
Useful when you've built a graph and want to perform multiple different analysis on it after excluding routes without having to rebuild the whole graph again Eg. find the shortest path between two vertices, then remove all these edge from this path and repeat to try to find the second-shortest path which doesn't use any of the same edges from the shortest path
172 lines
4.2 KiB
C++
172 lines
4.2 KiB
C++
/***************************************************************************
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qgsgraph.cpp
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--------------------------------------
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Date : 2011-04-01
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Copyright : (C) 2010 by Yakushev Sergey
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Email : YakushevS <at> list.ru
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****************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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/**
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* \file qgsgraph.cpp
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* \brief implementation QgsGraph, QgsGraphVertex, QgsGraphEdge
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*/
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#include "qgsgraph.h"
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#include <QSet>
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int QgsGraph::addVertex( const QgsPointXY &pt )
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{
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mGraphVertices[ mNextVertexId ] = QgsGraphVertex( pt );
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return mNextVertexId++;
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}
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int QgsGraph::addEdge( int fromVertexIdx, int toVertexIdx, const QVector< QVariant > &strategies )
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{
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QgsGraphEdge e;
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e.mStrategies = strategies;
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e.mToIdx = toVertexIdx;
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e.mFromIdx = fromVertexIdx;
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mGraphEdges[ mNextEdgeId ] = e;
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const int edgeIdx = mGraphEdges.size() - 1;
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mGraphVertices[ toVertexIdx ].mIncomingEdges.push_back( edgeIdx );
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mGraphVertices[ fromVertexIdx ].mOutgoingEdges.push_back( edgeIdx );
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return mNextEdgeId++;
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}
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const QgsGraphVertex &QgsGraph::vertex( int idx ) const
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{
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auto it = mGraphVertices.constFind( idx );
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if ( it != mGraphVertices.constEnd() )
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return ( it ).value();
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Q_ASSERT_X( false, "QgsGraph::vertex()", "Invalid vertex ID" );
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}
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void QgsGraph::removeVertex( int index )
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{
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auto it = mGraphVertices.constFind( index );
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if ( it != mGraphVertices.constEnd() )
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{
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QSet< int > affectedEdges = qgis::listToSet( it->incomingEdges() );
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affectedEdges.unite( qgis::listToSet( it->outgoingEdges() ) );
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mGraphVertices.erase( it );
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// remove affected edges
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for ( int edgeId : std::as_const( affectedEdges ) )
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{
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mGraphEdges.remove( edgeId );
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}
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}
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}
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const QgsGraphEdge &QgsGraph::edge( int idx ) const
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{
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auto it = mGraphEdges.constFind( idx );
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if ( it != mGraphEdges.constEnd() )
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return ( it ).value();
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Q_ASSERT_X( false, "QgsGraph::edge()", "Invalid edge ID" );
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}
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void QgsGraph::removeEdge( int index )
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{
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auto it = mGraphEdges.constFind( index );
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if ( it != mGraphEdges.constEnd() )
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{
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const int fromVertex = it->fromVertex();
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const int toVertex = it->toVertex();
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mGraphEdges.erase( it );
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// clean up affected vertices
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auto vertexIt = mGraphVertices.find( fromVertex );
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if ( vertexIt != mGraphVertices.end() )
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{
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vertexIt->mOutgoingEdges.removeAll( index );
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if ( vertexIt->mOutgoingEdges.empty() && vertexIt->mIncomingEdges.empty() )
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mGraphVertices.erase( vertexIt );
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}
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vertexIt = mGraphVertices.find( toVertex );
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if ( vertexIt != mGraphVertices.end() )
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{
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vertexIt->mIncomingEdges.removeAll( index );
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if ( vertexIt->mOutgoingEdges.empty() && vertexIt->mIncomingEdges.empty() )
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mGraphVertices.erase( vertexIt );
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}
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}
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}
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int QgsGraph::vertexCount() const
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{
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return mGraphVertices.size();
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}
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int QgsGraph::edgeCount() const
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{
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return mGraphEdges.size();
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}
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int QgsGraph::findVertex( const QgsPointXY &pt ) const
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{
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int i = 0;
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for ( i = 0; i < mGraphVertices.size(); ++i )
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{
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if ( mGraphVertices[ i ].point() == pt )
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{
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return i;
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}
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}
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return -1;
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}
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QVariant QgsGraphEdge::cost( int i ) const
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{
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return mStrategies[ i ];
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}
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QVector< QVariant > QgsGraphEdge::strategies() const
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{
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return mStrategies;
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}
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int QgsGraphEdge::fromVertex() const
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{
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return mFromIdx;
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}
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int QgsGraphEdge::toVertex() const
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{
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return mToIdx;
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}
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QgsGraphVertex::QgsGraphVertex( const QgsPointXY &point )
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: mCoordinate( point )
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{
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}
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QgsGraphEdgeIds QgsGraphVertex::incomingEdges() const
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{
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return mIncomingEdges;
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}
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QgsGraphEdgeIds QgsGraphVertex::outgoingEdges() const
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{
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return mOutgoingEdges;
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}
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QgsPointXY QgsGraphVertex::point() const
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{
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return mCoordinate;
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}
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