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QGIS/python/plugins/processing/algs/qgis/ShortestPathPointToLayer.py
Nyall Dawson c4f3832af2 Rename QgsGeometry::fromPolyline as QgsGeometry::fromPolylineXY 
and add new QgsGeometry::fromPolyline which uses QgsPoint

We want to encourage people not to use the QgsPointXY method, as it drops
Z/M values. So it's moved across to a different name to make way
for a new QgsGeometry::fromPolyline which uses a QgsPoint list
instead of QgsPointXY, thus keeping Z/M values intact.

Similarly, QgsPolyline now is a list of QgsPoint (keeping z/m values)
and the old 2d QgsPolyline type was renamed to QgsPolylineXY.

Making the QgsPoint method the "preferred" method and making linestrings
just as easy to create from z/m dimensioned points as 2d points is
important to push people to write code which does not discard
these important dimensions.

As a bonus, the QgsPoint methods are more efficient anyway, since
they don't require creation of a temporary list.
2017-10-22 18:10:14 +10:00

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# -*- coding: utf-8 -*-
"""
***************************************************************************
ShortestPathPointToLayer.py
---------------------
Date : December 2016
Copyright : (C) 2016 by Alexander Bruy
Email : alexander dot bruy at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
__author__ = 'Alexander Bruy'
__date__ = 'December 2016'
__copyright__ = '(C) 2016, Alexander Bruy'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'
import os
from collections import OrderedDict
from qgis.PyQt.QtCore import QVariant
from qgis.PyQt.QtGui import QIcon
from qgis.core import (QgsWkbTypes,
QgsUnitTypes,
QgsFeature,
QgsFeatureSink,
QgsGeometry,
QgsFeatureRequest,
QgsFields,
QgsField,
QgsMessageLog,
QgsProcessing,
QgsProcessingParameterEnum,
QgsProcessingParameterPoint,
QgsProcessingParameterField,
QgsProcessingParameterNumber,
QgsProcessingParameterString,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterFeatureSink,
QgsProcessingParameterDefinition)
from qgis.analysis import (QgsVectorLayerDirector,
QgsNetworkDistanceStrategy,
QgsNetworkSpeedStrategy,
QgsGraphBuilder,
QgsGraphAnalyzer
)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
class ShortestPathPointToLayer(QgisAlgorithm):
INPUT = 'INPUT'
START_POINT = 'START_POINT'
END_POINTS = 'END_POINTS'
STRATEGY = 'STRATEGY'
DIRECTION_FIELD = 'DIRECTION_FIELD'
VALUE_FORWARD = 'VALUE_FORWARD'
VALUE_BACKWARD = 'VALUE_BACKWARD'
VALUE_BOTH = 'VALUE_BOTH'
DEFAULT_DIRECTION = 'DEFAULT_DIRECTION'
SPEED_FIELD = 'SPEED_FIELD'
DEFAULT_SPEED = 'DEFAULT_SPEED'
TOLERANCE = 'TOLERANCE'
OUTPUT = 'OUTPUT'
def icon(self):
return QIcon(os.path.join(pluginPath, 'images', 'networkanalysis.svg'))
def group(self):
return self.tr('Network analysis')
def __init__(self):
super().__init__()
def initAlgorithm(self, config=None):
self.DIRECTIONS = OrderedDict([
(self.tr('Forward direction'), QgsVectorLayerDirector.DirectionForward),
(self.tr('Backward direction'), QgsVectorLayerDirector.DirectionForward),
(self.tr('Both directions'), QgsVectorLayerDirector.DirectionForward)])
self.STRATEGIES = [self.tr('Shortest'),
self.tr('Fastest')
]
self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
self.tr('Vector layer representing network'),
[QgsProcessing.TypeVectorLine]))
self.addParameter(QgsProcessingParameterPoint(self.START_POINT,
self.tr('Start point')))
self.addParameter(QgsProcessingParameterFeatureSource(self.END_POINTS,
self.tr('Vector layer with end points'),
[QgsProcessing.TypeVectorPoint]))
self.addParameter(QgsProcessingParameterEnum(self.STRATEGY,
self.tr('Path type to calculate'),
self.STRATEGIES,
defaultValue=0))
params = []
params.append(QgsProcessingParameterField(self.DIRECTION_FIELD,
self.tr('Direction field'),
None,
self.INPUT,
optional=True))
params.append(QgsProcessingParameterString(self.VALUE_FORWARD,
self.tr('Value for forward direction'),
optional=True))
params.append(QgsProcessingParameterString(self.VALUE_BACKWARD,
self.tr('Value for backward direction'),
optional=True))
params.append(QgsProcessingParameterString(self.VALUE_BOTH,
self.tr('Value for both directions'),
optional=True))
params.append(QgsProcessingParameterEnum(self.DEFAULT_DIRECTION,
self.tr('Default direction'),
list(self.DIRECTIONS.keys()),
defaultValue=2))
params.append(QgsProcessingParameterField(self.SPEED_FIELD,
self.tr('Speed field'),
None,
self.INPUT,
optional=True))
params.append(QgsProcessingParameterNumber(self.DEFAULT_SPEED,
self.tr('Default speed (km/h)'),
QgsProcessingParameterNumber.Double,
5.0, False, 0, 99999999.99))
params.append(QgsProcessingParameterNumber(self.TOLERANCE,
self.tr('Topology tolerance'),
QgsProcessingParameterNumber.Double,
0.0, False, 0, 99999999.99))
for p in params:
p.setFlags(p.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
self.addParameter(p)
self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT,
self.tr('Shortest path'),
QgsProcessing.TypeVectorLine))
def name(self):
return 'shortestpathpointtolayer'
def displayName(self):
return self.tr('Shortest path (point to layer)')
def processAlgorithm(self, parameters, context, feedback):
network = self.parameterAsSource(parameters, self.INPUT, context)
startPoint = self.parameterAsPoint(parameters, self.START_POINT, context, network.sourceCrs())
endPoints = self.parameterAsSource(parameters, self.END_POINTS, context)
strategy = self.parameterAsEnum(parameters, self.STRATEGY, context)
directionFieldName = self.parameterAsString(parameters, self.DIRECTION_FIELD, context)
forwardValue = self.parameterAsString(parameters, self.VALUE_FORWARD, context)
backwardValue = self.parameterAsString(parameters, self.VALUE_BACKWARD, context)
bothValue = self.parameterAsString(parameters, self.VALUE_BOTH, context)
defaultDirection = self.parameterAsEnum(parameters, self.DEFAULT_DIRECTION, context)
speedFieldName = self.parameterAsString(parameters, self.SPEED_FIELD, context)
defaultSpeed = self.parameterAsDouble(parameters, self.DEFAULT_SPEED, context)
tolerance = self.parameterAsDouble(parameters, self.TOLERANCE, context)
fields = QgsFields()
fields.append(QgsField('start', QVariant.String, '', 254, 0))
fields.append(QgsField('end', QVariant.String, '', 254, 0))
fields.append(QgsField('cost', QVariant.Double, '', 20, 7))
feat = QgsFeature()
feat.setFields(fields)
(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, QgsWkbTypes.LineString, network.sourceCrs())
directionField = -1
if directionFieldName:
directionField = network.fields().lookupField(directionFieldName)
speedField = -1
if speedFieldName:
speedField = network.fields().lookupField(speedFieldName)
director = QgsVectorLayerDirector(network,
directionField,
forwardValue,
backwardValue,
bothValue,
defaultDirection)
distUnit = context.project().crs().mapUnits()
multiplier = QgsUnitTypes.fromUnitToUnitFactor(distUnit, QgsUnitTypes.DistanceMeters)
if strategy == 0:
strategy = QgsNetworkDistanceStrategy()
else:
strategy = QgsNetworkSpeedStrategy(speedField,
defaultSpeed,
multiplier * 1000.0 / 3600.0)
multiplier = 3600
director.addStrategy(strategy)
builder = QgsGraphBuilder(network.sourceCrs(),
True,
tolerance)
feedback.pushInfo(self.tr('Loading end points...'))
request = QgsFeatureRequest()
request.setFlags(request.flags() ^ QgsFeatureRequest.SubsetOfAttributes)
request.setDestinationCrs(network.sourceCrs())
features = endPoints.getFeatures(request)
total = 100.0 / endPoints.featureCount() if endPoints.featureCount() else 0
points = [startPoint]
for current, f in enumerate(features):
if feedback.isCanceled():
break
points.append(f.geometry().asPoint())
feedback.setProgress(int(current * total))
feedback.pushInfo(self.tr('Building graph...'))
snappedPoints = director.makeGraph(builder, points, feedback)
feedback.pushInfo(self.tr('Calculating shortest paths...'))
graph = builder.graph()
idxStart = graph.findVertex(snappedPoints[0])
tree, cost = QgsGraphAnalyzer.dijkstra(graph, idxStart, 0)
route = []
nPoints = len(snappedPoints)
total = 100.0 / nPoints if nPoints else 1
for i in range(1, nPoints + 1):
if feedback.isCanceled():
break
idxEnd = graph.findVertex(snappedPoints[i])
if tree[idxEnd] == -1:
msg = self.tr('There is no route from start point ({}) to end point ({}).'.format(startPoint.toString(), points[i].toString()))
feedback.setProgressText(msg)
QgsMessageLog.logMessage(msg, self.tr('Processing'), QgsMessageLog.WARNING)
continue
cost = 0.0
current = idxEnd
while current != idxStart:
cost += graph.edge(tree[current]).cost(0)
route.append(graph.vertex(graph.edge(tree[current]).inVertex()).point())
current = graph.edge(tree[current]).outVertex()
route.append(snappedPoints[0])
route.reverse()
geom = QgsGeometry.fromPolylineXY(route)
feat.setGeometry(geom)
feat['start'] = startPoint.toString()
feat['end'] = points[i].toString()
feat['cost'] = cost / multiplier
sink.addFeature(feat, QgsFeatureSink.FastInsert)
route[:] = []
feedback.setProgress(int(i * total))
return {self.OUTPUT: dest_id}
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