QGIS » QGIS Application

# name :  MergeEdges_script

# author: Theresa Lichtenberger

# date   : 22.10.2018

# description: merges edges with the same edgeid

#           and adds two attributes for speed limits on each lane 

from qgis.core import *

from PyQt4.QtCore import *

from math import degrees

#***********Constants*************#

EDGEID = 'edgeid'

FROM = 'from'

TO = 'to'

PRIORITY = 'priority'

LENGTH = 'length'

TIME = 'time'

NODEID = 'nodeID'

COORD_X = 'x'

COORD_Y = 'y'

ID = 'id'

VTO = 'vto'

VFROM = 'vfrom'

NODE1 = 'node1'

NODE2 = 'node2'

#*******************************#

# input parameters 

##Edges=vector

##Nodes=vector

inLayerEdges = processing.getObject(Edges)

inNodes = processing.getObject(Nodes)

crs = inLayerEdges.crs().toWkt()

# get field indices for inputlayer

idxEdgeId = inLayerEdges.fieldNameIndex(ID)

idxPriority = inLayerEdges.fieldNameIndex(PRIORITY)

idxLength  = inLayerEdges.fieldNameIndex(LENGTH)

idxTime    = inLayerEdges.fieldNameIndex(TIME)

idxFrom  = inLayerEdges.fieldNameIndex(FROM)

idxTo  = inLayerEdges.fieldNameIndex(TO)

idx_id = inNodes.fieldNameIndex(NODEID)

idx_x = inNodes.fieldNameIndex(COORD_X)

idx_y = inNodes.fieldNameIndex(COORD_Y)

# Create output layer and specify geometry type

outLayer = QgsVectorLayer('Linestring?crs=' + crs, 'merged_edges', 'memory')

# Set the provider to accept the data source

outdp = outLayer.dataProvider()

# define attributes and add them to the vector layer

outdp.addAttributes([QgsField(EDGEID, QVariant.String),

                            QgsField(NODE1, QVariant.String),

                            QgsField(NODE2, QVariant.String),

                            QgsField(PRIORITY, QVariant.Int),

                            QgsField(VTO, QVariant.Double),

                            QgsField(VFROM, QVariant.Double)])

outLayer.updateFields()

# get field indices for outputlayer

outEdgeId = outdp.fieldNameIndex(EDGEID)

outNode1 = outdp.fieldNameIndex(NODE1)

outNode2 = outdp.fieldNameIndex(NODE2)

outPriority = outdp.fieldNameIndex(PRIORITY)

outVTo = outdp.fieldNameIndex(VTO)

outVFrom = outdp.fieldNameIndex(VFROM)

listOfEdgeIds = []

count = 0

flag = 0

# loop through edges of inLayerEdges and merge 

for feat in inLayerEdges.getFeatures():

    # create new edge (line) for outputLayer

    newEdge = QgsFeature(outLayer.pendingFields())

    currentPriority = feat.attributes()[idxPriority]

    currentEdgeId = feat.attributes()[idxEdgeId]

    if currentEdgeId.find('From') == -1:

        edgeIdTrimmed = currentEdgeId.replace('To', '')

    else:

        edgeIdTrimmed = currentEdgeId.replace('From', '')

    if edgeIdTrimmed in listOfEdgeIds:

        # if current edge id already processed -> skip it.

        #print "current edgeid already in list. Continue ..."

        continue

    else:      

        # if not, find all entries in the graph which share the same current edge id

        # and merge them

        listOfEdgeIds.append(edgeIdTrimmed)

        newEdge.setAttribute(EDGEID, edgeIdTrimmed)

        newEdge.setAttribute(PRIORITY, currentPriority)

        node1 = feat.attributes()[idxFrom]

        node2 = feat.attributes()[idxTo]

        newEdge.setAttribute(NODE1, node1)

        newEdge.setAttribute(NODE2, node2)

        # search for specific from_node by nodeID

        exp = QgsExpression('nodeID ILIKE \'' + node1 +'\' ')

        request = QgsFeatureRequest(exp)

        request.setLimit(1)

        for feat2 in inNodes.getFeatures(request):

            geomFrom = feat2.geometry()

            print geomFrom

        # search for specific to_node by nodeID

        exp = QgsExpression('nodeID ILIKE \'' + node2 +'\' ')

        request = QgsFeatureRequest(exp)

        request.setLimit(1)

        for feat2 in inNodes.getFeatures(request):

            geomTo = feat2.geometry()

            print geomTo

        # find all entries in the graph with current edge id

        exp = QgsExpression('id ILIKE \'' + edgeIdTrimmed + '%\' ')

        request = QgsFeatureRequest(exp)

        # loop through all egdes with the same current edgeids

        for feat1 in inLayerEdges.getFeatures(request):

            tempEdgeId = feat1.attributes()[idxEdgeId]

            length = feat1.attributes()[idxLength]

            time    = feat1.attributes()[idxTime]

            velocity = (length / time) * 3.6

            if tempEdgeId.find("From") is not -1:

                #print("Python found the string From!")

                newEdge.setAttribute(VFROM, velocity)

            elif tempEdgeId.find("To") is not -1:

                #print("Python found the string To!")

                newEdge.setAttribute(VTO, velocity)

            else:

                print("Python did NOT find the substring!")

        print "heyho"

        newEdge.setGeometry(QgsGeometry.fromPolyline([geomFrom.asPoint(),geomTo.asPoint()]))

        # add the feature to the layer

        (res, outFeats) = outdp.addFeatures([newEdge])

# Add the layer to the Layers panel

QgsMapLayerRegistry.instance().addMapLayer(outLayer)

print "Done ... "