QGIS API Documentation 3.41.0-Master (d5b93354e9c)
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qgsalgorithmserviceareafromlayer.cpp
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1/***************************************************************************
2 qgsalgorithmserviceareafromlayer.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 "qgsgeometryutils.h"
21#include "qgsgraphanalyzer.h"
22
24
25QString QgsServiceAreaFromLayerAlgorithm::name() const
26{
27 return QStringLiteral( "serviceareafromlayer" );
28}
29
30QString QgsServiceAreaFromLayerAlgorithm::displayName() const
31{
32 return QObject::tr( "Service area (from layer)" );
33}
34
35QStringList QgsServiceAreaFromLayerAlgorithm::tags() const
36{
37 return QObject::tr( "network,service,area,shortest,fastest" ).split( ',' );
38}
39
40QString QgsServiceAreaFromLayerAlgorithm::shortHelpString() const
41{
42 return QObject::tr( "This algorithm creates a new vector with all the edges or parts of "
43 "edges of a network line layer that can be reached within a distance "
44 "or a time, starting from features of a point layer. The distance and "
45 "the time (both referred to as \"travel cost\") must be specified "
46 "respectively in the network layer units or in hours." );
47}
48
49QgsServiceAreaFromLayerAlgorithm *QgsServiceAreaFromLayerAlgorithm::createInstance() const
50{
51 return new QgsServiceAreaFromLayerAlgorithm();
52}
53
54void QgsServiceAreaFromLayerAlgorithm::initAlgorithm( const QVariantMap & )
55{
56 addCommonParams();
57 addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "START_POINTS" ), QObject::tr( "Vector layer with start points" ), QList<int>() << static_cast<int>( Qgis::ProcessingSourceType::VectorPoint ) ) );
58
59 std::unique_ptr<QgsProcessingParameterNumber> travelCost = std::make_unique<QgsProcessingParameterNumber>( QStringLiteral( "TRAVEL_COST" ), QObject::tr( "Travel cost (distance for 'Shortest', time for 'Fastest')" ), Qgis::ProcessingNumberParameterType::Double, 0, true, 0 );
60 travelCost->setFlags( travelCost->flags() | Qgis::ProcessingParameterFlag::Hidden );
61 addParameter( travelCost.release() );
62
63 addParameter( new QgsProcessingParameterNumber( QStringLiteral( "TRAVEL_COST2" ), QObject::tr( "Travel cost (distance for 'Shortest', time for 'Fastest')" ), Qgis::ProcessingNumberParameterType::Double, 0, false, 0 ) );
64
65 std::unique_ptr<QgsProcessingParameterBoolean> includeBounds = std::make_unique<QgsProcessingParameterBoolean>( QStringLiteral( "INCLUDE_BOUNDS" ), QObject::tr( "Include upper/lower bound points" ), false, true );
66 includeBounds->setFlags( includeBounds->flags() | Qgis::ProcessingParameterFlag::Advanced );
67 addParameter( includeBounds.release() );
68
69 std::unique_ptr<QgsProcessingParameterNumber> maxPointDistanceFromNetwork = std::make_unique<QgsProcessingParameterDistance>( QStringLiteral( "POINT_TOLERANCE" ), QObject::tr( "Maximum point distance from network" ), QVariant(), QStringLiteral( "INPUT" ), true, 0 );
70 maxPointDistanceFromNetwork->setFlags( maxPointDistanceFromNetwork->flags() | Qgis::ProcessingParameterFlag::Advanced );
71 maxPointDistanceFromNetwork->setHelp( QObject::tr( "Specifies an optional limit on the distance from the points to the network layer. If a point is further from the network than this distance it will be treated as non-routable." ) );
72 addParameter( maxPointDistanceFromNetwork.release() );
73
74 std::unique_ptr<QgsProcessingParameterFeatureSink> outputLines = std::make_unique<QgsProcessingParameterFeatureSink>( QStringLiteral( "OUTPUT_LINES" ), QObject::tr( "Service area (lines)" ), Qgis::ProcessingSourceType::VectorLine, QVariant(), true );
75 outputLines->setCreateByDefault( true );
76 addParameter( outputLines.release() );
77
78 std::unique_ptr<QgsProcessingParameterFeatureSink> outputPoints = std::make_unique<QgsProcessingParameterFeatureSink>( QStringLiteral( "OUTPUT" ), QObject::tr( "Service area (boundary nodes)" ), Qgis::ProcessingSourceType::VectorPoint, QVariant(), true );
79 outputPoints->setCreateByDefault( false );
80 addParameter( outputPoints.release() );
81
82 std::unique_ptr<QgsProcessingParameterFeatureSink> outputNonRoutable = std::make_unique<QgsProcessingParameterFeatureSink>( QStringLiteral( "OUTPUT_NON_ROUTABLE" ), QObject::tr( "Non-routable features" ), Qgis::ProcessingSourceType::VectorPoint, QVariant(), true );
83 outputNonRoutable->setHelp( QObject::tr( "An optional output which will be used to store any input features which could not be routed (e.g. those which are too far from the network layer)." ) );
84 outputNonRoutable->setCreateByDefault( false );
85 addParameter( outputNonRoutable.release() );
86}
87
88QVariantMap QgsServiceAreaFromLayerAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
89{
90 loadCommonParams( parameters, context, feedback );
91
92 std::unique_ptr<QgsFeatureSource> startPoints( parameterAsSource( parameters, QStringLiteral( "START_POINTS" ), context ) );
93 if ( !startPoints )
94 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "START_POINTS" ) ) );
95
96 // use older deprecated travel cost style if specified, to maintain old api
97 const bool useOldTravelCost = parameters.value( QStringLiteral( "TRAVEL_COST" ) ).isValid();
98 double travelCost = parameterAsDouble( parameters, useOldTravelCost ? QStringLiteral( "TRAVEL_COST" ) : QStringLiteral( "TRAVEL_COST2" ), context );
99
100 int strategy = parameterAsInt( parameters, QStringLiteral( "STRATEGY" ), context );
101 if ( strategy && !useOldTravelCost )
102 travelCost *= mMultiplier;
103
104 bool includeBounds = true; // default to true to maintain 3.0 API
105 if ( parameters.contains( QStringLiteral( "INCLUDE_BOUNDS" ) ) )
106 {
107 includeBounds = parameterAsBool( parameters, QStringLiteral( "INCLUDE_BOUNDS" ), context );
108 }
109
110 QVector<QgsPointXY> points;
111 QHash<int, QgsAttributes> sourceAttributes;
112 loadPoints( startPoints.get(), points, sourceAttributes, context, feedback );
113
114 feedback->pushInfo( QObject::tr( "Building graph…" ) );
115 QVector<QgsPointXY> snappedPoints;
116 mDirector->makeGraph( mBuilder.get(), points, snappedPoints, feedback );
117
118 feedback->pushInfo( QObject::tr( "Calculating service areas…" ) );
119 std::unique_ptr<QgsGraph> graph( mBuilder->takeGraph() );
120
121 QgsFields fields = startPoints->fields();
122 fields.append( QgsField( QStringLiteral( "type" ), QMetaType::Type::QString ) );
123 fields.append( QgsField( QStringLiteral( "start" ), QMetaType::Type::QString ) );
124
125 QString pointsSinkId;
126 std::unique_ptr<QgsFeatureSink> pointsSink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, pointsSinkId, fields, Qgis::WkbType::MultiPoint, mNetwork->sourceCrs() ) );
127
128 QString linesSinkId;
129 std::unique_ptr<QgsFeatureSink> linesSink( parameterAsSink( parameters, QStringLiteral( "OUTPUT_LINES" ), context, linesSinkId, fields, Qgis::WkbType::MultiLineString, mNetwork->sourceCrs() ) );
130
131 QString nonRoutableSinkId;
132 std::unique_ptr<QgsFeatureSink> nonRoutableSink( parameterAsSink( parameters, QStringLiteral( "OUTPUT_NON_ROUTABLE" ), context, nonRoutableSinkId, startPoints->fields(), Qgis::WkbType::Point, mNetwork->sourceCrs() ) );
133
134 const double pointDistanceThreshold = parameters.value( QStringLiteral( "POINT_TOLERANCE" ) ).isValid() ? parameterAsDouble( parameters, QStringLiteral( "POINT_TOLERANCE" ), context ) : -1;
135
136 int idxStart;
137 QVector<int> tree;
138 QVector<double> costs;
139
140 int inboundEdgeIndex;
141 double startVertexCost, endVertexCost;
142 QgsPointXY startPoint, endPoint;
143 QgsGraphEdge edge;
144
145 QgsFeature feat;
146 QgsAttributes attributes;
147
148 const double step = snappedPoints.size() > 0 ? 100.0 / snappedPoints.size() : 1;
149 for ( int i = 0; i < snappedPoints.size(); i++ )
150 {
151 if ( feedback->isCanceled() )
152 {
153 break;
154 }
155
156 const QgsPointXY snappedPoint = snappedPoints.at( i );
157 const QgsPointXY originalPoint = points.at( i );
158
159 if ( pointDistanceThreshold >= 0 )
160 {
161 double distancePointToNetwork = 0;
162 try
163 {
164 distancePointToNetwork = mBuilder->distanceArea()->measureLine( originalPoint, snappedPoint );
165 }
166 catch ( QgsCsException & )
167 {
168 throw QgsProcessingException( QObject::tr( "An error occurred while calculating length" ) );
169 }
170
171 if ( distancePointToNetwork > pointDistanceThreshold )
172 {
173 feedback->pushWarning( QObject::tr( "Point is too far from the network layer (%1, maximum permitted is %2)" ).arg( distancePointToNetwork ).arg( pointDistanceThreshold ) );
174 if ( nonRoutableSink )
175 {
176 feat.setGeometry( QgsGeometry::fromPointXY( originalPoint ) );
177 attributes = sourceAttributes.value( i + 1 );
178 feat.setAttributes( attributes );
179 if ( !nonRoutableSink->addFeature( feat, QgsFeatureSink::FastInsert ) )
180 throw QgsProcessingException( writeFeatureError( nonRoutableSink.get(), parameters, QStringLiteral( "OUTPUT_NON_ROUTABLE" ) ) );
181 }
182
183 feedback->setProgress( i * step );
184 continue;
185 }
186 }
187
188 const QString originalPointString = originalPoint.toString();
189
190 idxStart = graph->findVertex( snappedPoint );
191
192 QgsGraphAnalyzer::dijkstra( graph.get(), idxStart, 0, &tree, &costs );
193
194 QgsMultiPointXY areaPoints;
195 QgsMultiPolylineXY lines;
196 QSet<int> vertices;
197
198 for ( int j = 0; j < costs.size(); j++ )
199 {
200 inboundEdgeIndex = tree.at( j );
201
202 if ( inboundEdgeIndex == -1 && j != idxStart )
203 {
204 // unreachable vertex
205 continue;
206 }
207
208 startVertexCost = costs.at( j );
209 if ( startVertexCost > travelCost )
210 {
211 // vertex is too expensive, discard
212 continue;
213 }
214
215 vertices.insert( j );
216 startPoint = graph->vertex( j ).point();
217
218 // find all edges coming from this vertex
219 const QList<int> outgoingEdges = graph->vertex( j ).outgoingEdges();
220 for ( int edgeId : outgoingEdges )
221 {
222 edge = graph->edge( edgeId );
223 endVertexCost = startVertexCost + edge.cost( 0 ).toDouble();
224 endPoint = graph->vertex( edge.toVertex() ).point();
225 if ( endVertexCost <= travelCost )
226 {
227 // end vertex is cheap enough to include
228 vertices.insert( edge.toVertex() );
229 lines.push_back( QgsPolylineXY() << startPoint << endPoint );
230 }
231 else
232 {
233 // travelCost sits somewhere on this edge, interpolate position
234 QgsPointXY interpolatedEndPoint = QgsGeometryUtils::interpolatePointOnLineByValue( startPoint.x(), startPoint.y(), startVertexCost, endPoint.x(), endPoint.y(), endVertexCost, travelCost );
235
236 areaPoints.push_back( interpolatedEndPoint );
237 lines.push_back( QgsPolylineXY() << startPoint << interpolatedEndPoint );
238 }
239 } // edges
240 } // costs
241
242 // convert to list and sort to maintain same order of points between algorithm runs
243 QList<int> verticesList = qgis::setToList( vertices );
244 areaPoints.reserve( verticesList.size() );
245 std::sort( verticesList.begin(), verticesList.end() );
246 for ( int v : verticesList )
247 {
248 areaPoints.push_back( graph->vertex( v ).point() );
249 }
250
251 if ( pointsSink )
252 {
253 QgsGeometry geomPoints = QgsGeometry::fromMultiPointXY( areaPoints );
254 feat.setGeometry( geomPoints );
255 attributes = sourceAttributes.value( i + 1 );
256 attributes << QStringLiteral( "within" ) << originalPointString;
257 feat.setAttributes( attributes );
258 if ( !pointsSink->addFeature( feat, QgsFeatureSink::FastInsert ) )
259 throw QgsProcessingException( writeFeatureError( pointsSink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
260
261 if ( includeBounds )
262 {
263 QgsMultiPointXY upperBoundary, lowerBoundary;
264 QVector<int> nodes;
265 nodes.reserve( costs.size() );
266
267 int vertexId;
268 for ( int v = 0; v < costs.size(); v++ )
269 {
270 if ( costs.at( v ) > travelCost && tree.at( v ) != -1 )
271 {
272 vertexId = graph->edge( tree.at( v ) ).fromVertex();
273 if ( costs.at( vertexId ) <= travelCost )
274 {
275 nodes.push_back( v );
276 }
277 }
278 } // costs
279
280 upperBoundary.reserve( nodes.size() );
281 lowerBoundary.reserve( nodes.size() );
282 for ( int n : std::as_const( nodes ) )
283 {
284 upperBoundary.push_back( graph->vertex( graph->edge( tree.at( n ) ).toVertex() ).point() );
285 lowerBoundary.push_back( graph->vertex( graph->edge( tree.at( n ) ).fromVertex() ).point() );
286 } // nodes
287
288 QgsGeometry geomUpper = QgsGeometry::fromMultiPointXY( upperBoundary );
289 QgsGeometry geomLower = QgsGeometry::fromMultiPointXY( lowerBoundary );
290
291 feat.setGeometry( geomUpper );
292 attributes = sourceAttributes.value( i + 1 );
293 attributes << QStringLiteral( "upper" ) << originalPointString;
294 feat.setAttributes( attributes );
295 if ( !pointsSink->addFeature( feat, QgsFeatureSink::FastInsert ) )
296 throw QgsProcessingException( writeFeatureError( pointsSink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
297
298 feat.setGeometry( geomLower );
299 attributes = sourceAttributes.value( i + 1 );
300 attributes << QStringLiteral( "lower" ) << originalPointString;
301 feat.setAttributes( attributes );
302 if ( !pointsSink->addFeature( feat, QgsFeatureSink::FastInsert ) )
303 throw QgsProcessingException( writeFeatureError( pointsSink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
304 } // includeBounds
305 }
306
307 if ( linesSink )
308 {
310 feat.setGeometry( geomLines );
311 attributes = sourceAttributes.value( i + 1 );
312 attributes << QStringLiteral( "lines" ) << originalPointString;
313 feat.setAttributes( attributes );
314 if ( !linesSink->addFeature( feat, QgsFeatureSink::FastInsert ) )
315 throw QgsProcessingException( writeFeatureError( linesSink.get(), parameters, QStringLiteral( "OUTPUT_LINES" ) ) );
316 }
317
318 feedback->setProgress( i * step );
319 } // snappedPoints
320
321 QVariantMap outputs;
322 if ( pointsSink )
323 {
324 pointsSink->finalize();
325 outputs.insert( QStringLiteral( "OUTPUT" ), pointsSinkId );
326 }
327 if ( linesSink )
328 {
329 linesSink->finalize();
330 outputs.insert( QStringLiteral( "OUTPUT_LINES" ), linesSinkId );
331 }
332 if ( nonRoutableSink )
333 {
334 nonRoutableSink->finalize();
335 outputs.insert( QStringLiteral( "OUTPUT_NON_ROUTABLE" ), nonRoutableSinkId );
336 }
337
338 return outputs;
339}
340
@ VectorPoint
Vector point layers.
@ VectorLine
Vector line layers.
@ MultiPoint
MultiPoint.
@ MultiLineString
MultiLineString.
@ Hidden
Parameter is hidden and should not be shown to users.
@ Advanced
Parameter is an advanced parameter which should be hidden from users by default.
A vector of attributes.
Custom exception class for Coordinate Reference System related exceptions.
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
void setAttributes(const QgsAttributes &attrs)
Sets the feature's attributes.
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
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:46
bool append(const QgsField &field, Qgis::FieldOrigin origin=Qgis::FieldOrigin::Provider, int originIndex=-1)
Appends a field.
Definition qgsfields.cpp:70
static QgsPointXY interpolatePointOnLineByValue(double x1, double y1, double v1, double x2, double y2, double v2, double value)
Interpolates the position of a point along the line from (x1, y1) to (x2, y2).
A geometry is the spatial representation of a feature.
static QgsGeometry fromMultiPolylineXY(const QgsMultiPolylineXY &multiline)
Creates a new geometry from a QgsMultiPolylineXY object.
static QgsGeometry fromMultiPointXY(const QgsMultiPointXY &multipoint)
Creates a new geometry from a QgsMultiPointXY object.
static QgsGeometry fromPointXY(const QgsPointXY &point)
Creates a new geometry from a QgsPointXY object.
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.
This class implements a graph edge.
Definition qgsgraph.h:44
int toVertex() const
Returns the index of the vertex at the end of this edge.
Definition qgsgraph.cpp:184
QVariant cost(int strategyIndex) const
Returns edge cost calculated using specified strategy.
Definition qgsgraph.cpp:169
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.
double y
Definition qgspointxy.h:64
double x
Definition qgspointxy.h:63
Contains information about the context in which a processing algorithm is executed.
Custom exception class for processing related exceptions.
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 pushWarning(const QString &warning)
Pushes a warning informational message from the algorithm.
An input feature source (such as vector layers) parameter for processing algorithms.
A numeric parameter for processing algorithms.
QVector< QgsPolylineXY > QgsMultiPolylineXY
A collection of QgsPolylines that share a common collection of attributes.
Definition qgsgeometry.h:84
QVector< QgsPointXY > QgsMultiPointXY
A collection of QgsPoints that share a common collection of attributes.
Definition qgsgeometry.h:80
QVector< QgsPointXY > QgsPolylineXY
Polyline as represented as a vector of two-dimensional points.
Definition qgsgeometry.h:62