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[processing] port Random points along lines
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@alexbruy
alexbruy committed Jul 24, 2017
1 parent f8b0c06 commit c7645a3
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Showing 2 changed files with 78 additions and 37 deletions.
3 changes: 2 additions & 1 deletion python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py
View file
Expand Up @@ -84,6 +84,7 @@
from .PostGISExecuteSQL import PostGISExecuteSQL
from .RandomExtract import RandomExtract
from .RandomExtractWithinSubsets import RandomExtractWithinSubsets
from .RandomPointsAlongLines import RandomPointsAlongLines
from .RandomPointsExtent import RandomPointsExtent
from .RandomPointsLayer import RandomPointsLayer
from .RandomPointsPolygons import RandomPointsPolygons
Expand Down Expand Up @@ -144,7 +145,6 @@
# from .PointsDisplacement import PointsDisplacement
# from .PointsFromPolygons import PointsFromPolygons
# from .PointsFromLines import PointsFromLines
# from .RandomPointsAlongLines import RandomPointsAlongLines
# from .PointsToPaths import PointsToPaths
# from .SetVectorStyle import SetVectorStyle
# from .SetRasterStyle import SetRasterStyle
Expand Down Expand Up @@ -271,6 +271,7 @@ def getAlgs(self):
PostGISExecuteSQL(),
RandomExtract(),
RandomExtractWithinSubsets(),
RandomPointsAlongLines(),
RandomPointsExtent(),
RandomPointsLayer(),
RandomPointsPolygons(),
Expand Down
112 changes: 76 additions & 36 deletions python/plugins/processing/algs/qgis/RandomPointsAlongLines.py
View file
Expand Up @@ -29,33 +29,37 @@
import random

from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsApplication,
from qgis.core import (QgsField,
QgsFeatureSink,
QgsFeature,
QgsFields,
QgsField,
QgsGeometry,
QgsSpatialIndex,
QgsPoint,
QgsPointXY,
QgsWkbTypes,
QgsDistanceArea,
QgsSpatialIndex,
QgsFeatureRequest,
QgsFeature,
QgsPointXY,
QgsMessageLog,
QgsDistanceArea,
QgsProject,
QgsProcessingUtils)
QgsProcessing,
QgsProcessingException,
QgsProcessingParameterNumber,
QgsProcessingParameterBoolean,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterFeatureSink,
QgsProcessingParameterDefinition)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterNumber
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector
from processing.tools import vector


class RandomPointsAlongLines(QgisAlgorithm):

VECTOR = 'VECTOR'
POINT_NUMBER = 'POINT_NUMBER'
INPUT = 'INPUT'
POINTS_NUMBER = 'POINTS_NUMBER'
MIN_DISTANCE = 'MIN_DISTANCE'
ADD_Z = 'ADD_Z'
ADD_M = 'ADD_M'
OUTPUT = 'OUTPUT'

def group(self):
Expand All @@ -65,13 +69,31 @@ def __init__(self):
super().__init__()

def initAlgorithm(self, config=None):
self.addParameter(ParameterVector(self.VECTOR,
self.tr('Input layer'), [dataobjects.TYPE_VECTOR_LINE]))
self.addParameter(ParameterNumber(self.POINT_NUMBER,
self.tr('Number of points'), 1, None, 1))
self.addParameter(ParameterNumber(self.MIN_DISTANCE,
self.tr('Minimum distance'), 0.0, None, 0.0))
self.addOutput(OutputVector(self.OUTPUT, self.tr('Random points'), datatype=[dataobjects.TYPE_VECTOR_POINT]))
self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
self.tr('Input layer'),
[QgsProcessing.TypeVectorLine]))
self.addParameter(QgsProcessingParameterNumber(self.POINTS_NUMBER,
self.tr('Number of points'),
QgsProcessingParameterNumber.Integer,
1, False, 1, 1000000000))
self.addParameter(QgsProcessingParameterNumber(self.MIN_DISTANCE,
self.tr('Minimum distance between points'),
QgsProcessingParameterNumber.Double,
0, False, 0, 1000000000))
params = []
params.append(QgsProcessingParameterBoolean(self.ADD_Z,
self.tr('Add Z coordinate'),
False))
params.append(QgsProcessingParameterBoolean(self.ADD_M,
self.tr('Add M coordinate'),
False))
for p in params:
p.setFlags(p.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
self.addParameter(p)

self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT,
self.tr('Random points'),
type=QgsProcessing.TypeVectorPoint))

def name(self):
return 'randompointsalongline'
Expand All @@ -80,35 +102,48 @@ def displayName(self):
return self.tr('Random points along line')

def processAlgorithm(self, parameters, context, feedback):
layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.VECTOR), context)
pointCount = float(self.getParameterValue(self.POINT_NUMBER))
minDistance = float(self.getParameterValue(self.MIN_DISTANCE))
source = self.parameterAsSource(parameters, self.INPUT, context)
pointCount = self.parameterAsDouble(parameters, self.POINTS_NUMBER, context)
minDistance = self.parameterAsDouble(parameters, self.MIN_DISTANCE, context)
addZ = self.parameterAsBool(parameters, self.ADD_Z, context)
addM = self.parameterAsBool(parameters, self.ADD_M, context)

fields = QgsFields()
fields.append(QgsField('id', QVariant.Int, '', 10, 0))
writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fields, QgsWkbTypes.Point, layer.crs(), context)

wkbType = QgsWkbTypes.Point
if addZ:
wkbType = QgsWkbTypes.addZ(wkbType)
if addM:
wkbType = QgsWkbTypes.addM(wkbType)

(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, wkbType, source.sourceCrs())

nPoints = 0
nIterations = 0
maxIterations = pointCount * 200
featureCount = layer.featureCount()
featureCount = source.featureCount()
total = 100.0 / pointCount if pointCount else 1

index = QgsSpatialIndex()
points = dict()

da = QgsDistanceArea()
da.setSourceCrs(layer.sourceCrs())
da.setSourceCrs(source.sourceCrs())
da.setEllipsoid(QgsProject.instance().ellipsoid())

request = QgsFeatureRequest()

random.seed()

while nIterations < maxIterations and nPoints < pointCount:
if feedback.isCanceled():
break

# pick random feature
fid = random.randint(0, featureCount - 1)
f = next(layer.getFeatures(request.setFilterFid(fid).setSubsetOfAttributes([])))
f = next(source.getFeatures(request.setFilterFid(fid).setSubsetOfAttributes([])))
fGeom = f.geometry()

if fGeom.isMultipart():
Expand All @@ -135,23 +170,28 @@ def processAlgorithm(self, parameters, context, feedback):
ry = (startPoint.y() + d * endPoint.y()) / (1 + d)

# generate random point
pnt = QgsPointXY(rx, ry)
geom = QgsGeometry.fromPoint(pnt)
if vector.checkMinDistance(pnt, index, minDistance, points):
pnt = QgsPoint(rx, ry)
p = QgsPointXY(rx, ry)
if addZ:
pnt.addZValue(0.0)
if addM:
pnt.addMValue(0.0)
geom = QgsGeometry(pnt)
if vector.checkMinDistance(p, index, minDistance, points):
f = QgsFeature(nPoints)
f.initAttributes(1)
f.setFields(fields)
f.setAttribute('id', nPoints)
f.setGeometry(geom)
writer.addFeature(f, QgsFeatureSink.FastInsert)
sink.addFeature(f, QgsFeatureSink.FastInsert)
index.insertFeature(f)
points[nPoints] = pnt
points[nPoints] = p
nPoints += 1
feedback.setProgress(int(nPoints * total))
nIterations += 1

if nPoints < pointCount:
QgsMessageLog.logMessage(self.tr('Can not generate requested number of random points. '
'Maximum number of attempts exceeded.'), self.tr('Processing'), QgsMessageLog.INFO)
feedback.pushInfo(self.tr('Could not generate requested number of random points. '
'Maximum number of attempts exceeded.'))

del writer
return {self.OUTPUT: dest_id}

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