QGIS API Documentation 3.37.0-Master (fdefdf9c27f)
qgsalgorithmshortestpathpointtolayer.cpp
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1/***************************************************************************
2 qgsalgorithmshortestpathpointtolayer.cpp
3 ---------------------
4 begin : July 2018
5 copyright : (C) 2018 by Alexander Bruy
6 email : alexander dot bruy at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
19
20#include "qgsgraphanalyzer.h"
21
22#include "qgsmessagelog.h"
23
25
26QString QgsShortestPathPointToLayerAlgorithm::name() const
27{
28 return QStringLiteral( "shortestpathpointtolayer" );
29}
30
31QString QgsShortestPathPointToLayerAlgorithm::displayName() const
32{
33 return QObject::tr( "Shortest path (point to layer)" );
34}
35
36QStringList QgsShortestPathPointToLayerAlgorithm::tags() const
37{
38 return QObject::tr( "network,path,shortest,fastest" ).split( ',' );
39}
40
41QString QgsShortestPathPointToLayerAlgorithm::shortHelpString() const
42{
43 return QObject::tr( "This algorithm computes optimal (shortest or fastest) route between given start point and multiple end points defined by point vector layer." );
44}
45
46QgsShortestPathPointToLayerAlgorithm *QgsShortestPathPointToLayerAlgorithm::createInstance() const
47{
48 return new QgsShortestPathPointToLayerAlgorithm();
49}
50
51void QgsShortestPathPointToLayerAlgorithm::initAlgorithm( const QVariantMap & )
52{
53 addCommonParams();
54 addParameter( new QgsProcessingParameterPoint( QStringLiteral( "START_POINT" ), QObject::tr( "Start point" ) ) );
55 addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "END_POINTS" ), QObject::tr( "Vector layer with end points" ), QList< int >() << static_cast< int >( Qgis::ProcessingSourceType::VectorPoint ) ) );
56
57 addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Shortest path" ), Qgis::ProcessingSourceType::VectorLine ) );
58}
59
60QVariantMap QgsShortestPathPointToLayerAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
61{
62 loadCommonParams( parameters, context, feedback );
63
64 const QgsPointXY startPoint = parameterAsPoint( parameters, QStringLiteral( "START_POINT" ), context, mNetwork->sourceCrs() );
65
66 std::unique_ptr< QgsFeatureSource > endPoints( parameterAsSource( parameters, QStringLiteral( "END_POINTS" ), context ) );
67 if ( !endPoints )
68 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "END_POINTS" ) ) );
69
70 QgsFields fields = endPoints->fields();
71 fields.append( QgsField( QStringLiteral( "start" ), QVariant::String ) );
72 fields.append( QgsField( QStringLiteral( "end" ), QVariant::String ) );
73 fields.append( QgsField( QStringLiteral( "cost" ), QVariant::Double ) );
74
75 QString dest;
76 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, Qgis::WkbType::LineString, mNetwork->sourceCrs(), QgsFeatureSink::RegeneratePrimaryKey ) );
77 if ( !sink )
78 throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
79
80 QVector< QgsPointXY > points;
81 points.push_front( startPoint );
82 QHash< int, QgsAttributes > sourceAttributes;
83 loadPoints( endPoints.get(), points, sourceAttributes, context, feedback );
84
85 feedback->pushInfo( QObject::tr( "Building graph…" ) );
86 QVector< QgsPointXY > snappedPoints;
87 mDirector->makeGraph( mBuilder.get(), points, snappedPoints, feedback );
88
89 feedback->pushInfo( QObject::tr( "Calculating shortest paths…" ) );
90 std::unique_ptr< QgsGraph > graph( mBuilder->takeGraph() );
91 const int idxStart = graph->findVertex( snappedPoints[0] );
92 int idxEnd;
93
94 QVector< int > tree;
95 QVector< double > costs;
96 QgsGraphAnalyzer::dijkstra( graph.get(), idxStart, 0, &tree, &costs );
97
98 QVector<QgsPointXY> route;
99 double cost;
100
101 QgsFeature feat;
102 feat.setFields( fields );
103 QgsAttributes attributes;
104
105 const double step = points.size() > 0 ? 100.0 / points.size() : 1;
106 for ( int i = 1; i < points.size(); i++ )
107 {
108 if ( feedback->isCanceled() )
109 {
110 break;
111 }
112
113 idxEnd = graph->findVertex( snappedPoints[i] );
114 if ( tree.at( idxEnd ) == -1 )
115 {
116 feedback->reportError( QObject::tr( "There is no route from start point (%1) to end point (%2)." )
117 .arg( startPoint.toString(),
118 points[i].toString() ) );
119 feat.clearGeometry();
120 attributes = sourceAttributes.value( i );
121 attributes.append( QVariant() );
122 attributes.append( points[i].toString() );
123 feat.setAttributes( attributes );
124 if ( !sink->addFeature( feat, QgsFeatureSink::FastInsert ) )
125 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
126 continue;
127 }
128
129 route.clear();
130 route.push_front( graph->vertex( idxEnd ).point() );
131 cost = costs.at( idxEnd );
132 while ( idxEnd != idxStart )
133 {
134 idxEnd = graph->edge( tree.at( idxEnd ) ).fromVertex();
135 route.push_front( graph->vertex( idxEnd ).point() );
136 }
137
138 const QgsGeometry geom = QgsGeometry::fromPolylineXY( route );
139 QgsFeature feat;
140 feat.setFields( fields );
141 attributes = sourceAttributes.value( i );
142 attributes.append( startPoint.toString() );
143 attributes.append( points[i].toString() );
144 attributes.append( cost / mMultiplier );
145 feat.setAttributes( attributes );
146 feat.setGeometry( geom );
147 if ( !sink->addFeature( feat, QgsFeatureSink::FastInsert ) )
148 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
149
150 feedback->setProgress( i * step );
151 }
152
153 QVariantMap outputs;
154 outputs.insert( QStringLiteral( "OUTPUT" ), dest );
155 return outputs;
156}
157
@ VectorPoint
Vector point layers.
@ VectorLine
Vector line layers.
@ LineString
LineString.
A vector of attributes.
Definition: qgsattributes.h:59
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
@ RegeneratePrimaryKey
This flag indicates, that a primary key field cannot be guaranteed to be unique and the sink should i...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
void setAttributes(const QgsAttributes &attrs)
Sets the feature's attributes.
Definition: qgsfeature.cpp:160
void setFields(const QgsFields &fields, bool initAttributes=false)
Assigns a field map with the feature to allow attribute access by attribute name.
Definition: qgsfeature.cpp:195
void clearGeometry()
Removes any geometry associated with the feature.
Definition: qgsfeature.cpp:181
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
Definition: qgsfeature.cpp:167
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition: qgsfeedback.h:53
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition: qgsfeedback.h:61
Encapsulate a field in an attribute table or data source.
Definition: qgsfield.h:53
Container of fields for a vector layer.
Definition: qgsfields.h:45
bool append(const QgsField &field, FieldOrigin origin=OriginProvider, int originIndex=-1)
Appends a field. The field must have unique name, otherwise it is rejected (returns false)
Definition: qgsfields.cpp:59
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:162
static QgsGeometry fromPolylineXY(const QgsPolylineXY &polyline)
Creates a new LineString geometry from a list of QgsPointXY points.
static void dijkstra(const QgsGraph *source, int startVertexIdx, int criterionNum, QVector< int > *resultTree=nullptr, QVector< double > *resultCost=nullptr)
Solve shortest path problem using Dijkstra algorithm.
A class to represent a 2D point.
Definition: qgspointxy.h:60
QString toString(int precision=-1) const
Returns a string representation of the point (x, y) with a preset precision.
Definition: qgspointxy.cpp:51
Contains information about the context in which a processing algorithm is executed.
Custom exception class for processing related exceptions.
Definition: qgsexception.h:83
Base class for providing feedback from a processing algorithm.
virtual void pushInfo(const QString &info)
Pushes a general informational message from the algorithm.
virtual void reportError(const QString &error, bool fatalError=false)
Reports that the algorithm encountered an error while executing.
A feature sink output for processing algorithms.
An input feature source (such as vector layers) parameter for processing algorithms.
A point parameter for processing algorithms.