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201 lines
8.5 KiB
Python
201 lines
8.5 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ShortestPath.py
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---------------------
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Date : November 2016
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Copyright : (C) 2016 by Alexander Bruy
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Email : alexander dot bruy at gmail dot com
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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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__author__ = 'Alexander Bruy'
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__date__ = 'November 2016'
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__copyright__ = '(C) 2016, Alexander Bruy'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import QgsWkbTypes, QgsFeature, QgsGeometry, QgsPoint
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from qgis.analysis import (QgsVectorLayerDirector,
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QgsNetworkDistanceStrategy,
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QgsGraphBuilder,
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QgsGraphAnalyzer
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)
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from qgis.utils import iface
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import (ParameterVector,
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ParameterPoint,
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ParameterNumber,
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ParameterString,
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ParameterTableField,
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ParameterSelection
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)
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from processing.core.outputs import (OutputNumber,
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OutputVector
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)
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from processing.tools import dataobjects
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class ShortestPath(GeoAlgorithm):
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INPUT_VECTOR = 'INPUT_VECTOR'
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START_POINT = 'START_POINT'
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END_POINT = 'END_POINT'
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DIRECTION_FIELD = 'DIRECTION_FIELD'
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VALUE_FORWARD = 'VALUE_FORWARD'
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VALUE_BACKWARD = 'VALUE_BACKWARD'
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VALUE_BOTH = 'VALUE_BOTH'
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DEFAULT_DIRECTION = 'DEFAULT_DIRECTION'
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TOLERANCE = 'TOLERANCE'
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PATH_LENGTH = 'PATH_LENGTH'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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def getIcon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'networkanalysis.svg'))
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def defineCharacteristics(self):
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self.DIRECTIONS = {self.tr('Forward direction'): QgsVectorLayerDirector.DirectionForward,
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self.tr('Backward direction'): QgsVectorLayerDirector.DirectionForward,
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self.tr('Both directions'): QgsVectorLayerDirector.DirectionForward
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}
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self.UNITS = {self.tr('Meters'): 1,
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self.tr('Kilometers'): 1000
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}
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self.name, self.i18n_name = self.trAlgorithm('Shortest path')
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self.group, self.i18n_group = self.trAlgorithm('Network analysis')
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self.addParameter(ParameterVector(self.INPUT_VECTOR,
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self.tr('Vector layer representing road network'),
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[dataobjects.TYPE_VECTOR_LINE]))
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self.addParameter(ParameterPoint(self.START_POINT,
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self.tr('Start point')))
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self.addParameter(ParameterPoint(self.END_POINT,
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self.tr('End point')))
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params = []
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params.append(ParameterTableField(self.DIRECTION_FIELD,
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self.tr('Road direction field'),
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self.INPUT_VECTOR,
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optional=True))
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params.append(ParameterString(self.VALUE_FORWARD,
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self.tr('Value for forward direction'),
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'',
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optional=True))
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params.append(ParameterString(self.VALUE_BACKWARD,
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self.tr('Value for backward direction'),
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'',
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optional=True))
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params.append(ParameterString(self.VALUE_BOTH,
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self.tr('Value for both directions'),
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'',
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optional=True))
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params.append(ParameterSelection(self.DEFAULT_DIRECTION,
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self.tr('Default road direction'),
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list(self.DIRECTIONS.keys()),
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default=2))
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params.append(ParameterNumber(self.TOLERANCE,
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self.tr('Topology tolerance'),
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0.0, 0.0, 99999999.999999))
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for p in params:
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p.isAdvanced = True
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self.addParameter(p)
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self.addOutput(OutputNumber(self.PATH_LENGTH,
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self.tr('Path length')))
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self.addOutput(OutputVector(self.OUTPUT_LAYER,
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self.tr('Shortest path'),
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datatype=[dataobjects.TYPE_VECTOR_LINE]))
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def processAlgorithm(self, progress):
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layer = dataobjects.getObjectFromUri(
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self.getParameterValue(self.INPUT_VECTOR))
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startPoint = self.getParameterValue(self.START_POINT)
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endPoint = self.getParameterValue(self.END_POINT)
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fieldName = self.getParameterValue(self.DIRECTION_FIELD)
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forwardValue = self.getParameterValue(self.VALUE_FORWARD)
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backwardValue = self.getParameterValue(self.VALUE_BACKWARD)
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bothValue = self.getParameterValue(self.VALUE_BOTH)
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defaultDirection = self.getParameterValue(self.DEFAULT_DIRECTION)
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tolerance = self.getParameterValue(self.TOLERANCE)
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writer = self.getOutputFromName(
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self.OUTPUT_LAYER).getVectorWriter(
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layer.fields().toList(),
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QgsWkbTypes.LineString,
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layer.crs())
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tmp = startPoint.split(',')
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startPoint = QgsPoint(float(tmp[0]), float(tmp[1]))
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tmp = endPoint.split(',')
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endPoint = QgsPoint(float(tmp[0]), float(tmp[1]))
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field = -1
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if fieldName is not None:
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field = layer.fields().lookupField(fieldName)
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director = QgsVectorLayerDirector(layer,
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field,
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forwardValue,
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backwardValue,
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bothValue,
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defaultDirection)
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strategy = QgsNetworkDistanceStrategy()
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director.addStrategy(strategy)
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builder = QgsGraphBuilder(iface.mapCanvas().mapSettings().destinationCrs(),
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iface.mapCanvas().hasCrsTransformEnabled(),
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tolerance)
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progress.setInfo(self.tr('Building graph...'))
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snappedPoints = director.makeGraph(builder, [startPoint, endPoint])
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progress.setInfo(self.tr('Calculating shortest path...'))
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graph = builder.graph()
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idxStart = graph.findVertex(snappedPoints[0])
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idxEnd = graph.findVertex(snappedPoints[1])
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tree, cost = QgsGraphAnalyzer.dijkstra(graph, idxStart, 0)
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if tree[idxEnd] == -1:
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raise GeoAlgorithmExecutionException(
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self.tr('There is no route from start point to end point.'))
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route = []
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cost = 0.0
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current = idxEnd
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while current != idxStart:
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cost += graph.edge(tree[current]).cost(0)
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route.append(graph.vertex(graph.edge(tree[current]).inVertex()).point())
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current = graph.edge(tree[current]).outVertex()
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route.append(snappedPoints[0])
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route.reverse()
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self.setOutputValue(self.PATH_LENGTH, cost)
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progress.setInfo(self.tr('Writting results...'))
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geom = QgsGeometry.fromPolyline(route)
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feat = QgsFeature()
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feat.setGeometry(geom)
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writer.addFeature(feat)
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del writer
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