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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
247 lines
11 KiB
Python
247 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ShortestPathPointToPoint.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 collections import OrderedDict
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from qgis.PyQt.QtCore import QVariant
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import QgsWkbTypes, QgsUnitTypes, QgsFeature, QgsGeometry, QgsPoint, QgsFields, QgsField
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from qgis.analysis import (QgsVectorLayerDirector,
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QgsNetworkDistanceStrategy,
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QgsNetworkSpeedStrategy,
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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 ShortestPathPointToPoint(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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STRATEGY = 'STRATEGY'
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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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SPEED_FIELD = 'SPEED_FIELD'
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DEFAULT_SPEED = 'DEFAULT_SPEED'
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TOLERANCE = 'TOLERANCE'
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TRAVEL_COST = 'TRAVEL_COST'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'networkanalysis.svg'))
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def group(self):
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return self.tr('Network analysis')
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def name(self):
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return 'shortestpathpointtopoint'
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def displayName(self):
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return self.tr('Shortest path (point to point)')
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def defineCharacteristics(self):
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self.DIRECTIONS = OrderedDict([
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(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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self.STRATEGIES = [self.tr('Shortest'),
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self.tr('Fastest')
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]
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self.addParameter(ParameterVector(self.INPUT_VECTOR,
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self.tr('Vector layer representing 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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self.addParameter(ParameterSelection(self.STRATEGY,
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self.tr('Path type to calculate'),
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self.STRATEGIES,
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default=0))
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params = []
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params.append(ParameterTableField(self.DIRECTION_FIELD,
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self.tr('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 direction'),
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list(self.DIRECTIONS.keys()),
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default=2))
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params.append(ParameterTableField(self.SPEED_FIELD,
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self.tr('Speed field'),
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self.INPUT_VECTOR,
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optional=True))
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params.append(ParameterNumber(self.DEFAULT_SPEED,
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self.tr('Default speed (km/h)'),
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0.0, 99999999.999999, 5.0))
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params.append(ParameterNumber(self.TOLERANCE,
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self.tr('Topology tolerance'),
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0.0, 99999999.999999, 0.0))
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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.TRAVEL_COST,
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self.tr('Travel cost')))
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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, context, feedback):
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_VECTOR), context)
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startPoint = self.getParameterValue(self.START_POINT)
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endPoint = self.getParameterValue(self.END_POINT)
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strategy = self.getParameterValue(self.STRATEGY)
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directionFieldName = 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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bothValue = self.getParameterValue(self.VALUE_BOTH)
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defaultDirection = self.getParameterValue(self.DEFAULT_DIRECTION)
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speedFieldName = self.getParameterValue(self.SPEED_FIELD)
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defaultSpeed = self.getParameterValue(self.DEFAULT_SPEED)
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tolerance = self.getParameterValue(self.TOLERANCE)
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fields = QgsFields()
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fields.append(QgsField('start', QVariant.String, '', 254, 0))
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fields.append(QgsField('end', QVariant.String, '', 254, 0))
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fields.append(QgsField('cost', QVariant.Double, '', 20, 7))
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writer = self.getOutputFromName(
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self.OUTPUT_LAYER).getVectorWriter(fields.toList(), QgsWkbTypes.LineString, layer.crs(), context)
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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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directionField = -1
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if directionFieldName is not None:
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directionField = layer.fields().lookupField(directionFieldName)
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speedField = -1
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if speedFieldName is not None:
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speedField = layer.fields().lookupField(speedFieldName)
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director = QgsVectorLayerDirector(layer,
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directionField,
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forwardValue,
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backwardValue,
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bothValue,
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defaultDirection)
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distUnit = iface.mapCanvas().mapSettings().destinationCrs().mapUnits()
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multiplier = QgsUnitTypes.fromUnitToUnitFactor(distUnit, QgsUnitTypes.DistanceMeters)
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if strategy == 0:
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strategy = QgsNetworkDistanceStrategy()
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else:
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strategy = QgsNetworkSpeedStrategy(speedField,
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defaultSpeed,
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multiplier * 1000.0 / 3600.0)
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multiplier = 3600
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director.addStrategy(strategy)
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builder = QgsGraphBuilder(iface.mapCanvas().mapSettings().destinationCrs(),
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True,
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tolerance)
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feedback.pushInfo(self.tr('Building graph...'))
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snappedPoints = director.makeGraph(builder, [startPoint, endPoint])
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feedback.pushInfo(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.TRAVEL_COST, cost / multiplier)
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feedback.pushInfo(self.tr('Writing results...'))
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geom = QgsGeometry.fromPolyline(route)
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feat = QgsFeature()
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feat.setFields(fields)
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feat['start'] = startPoint.toString()
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feat['end'] = endPoint.toString()
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feat['cost'] = cost / multiplier
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feat.setGeometry(geom)
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writer.addFeature(feat)
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del writer
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