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b1cadb1822
have specific icons, instead of generic qgis icon We consider these 'top level' algorithms, and using the standard algorithm icon should help reflect this and differentiate them from 3rd party algorithms.
152 lines
5.8 KiB
Python
152 lines
5.8 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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RandomPointsAlongLines.py
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---------------------
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Date : April 2014
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Copyright : (C) 2014 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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from builtins import next
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__author__ = 'Alexander Bruy'
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__date__ = 'April 2014'
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__copyright__ = '(C) 2014, 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 random
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsApplication,
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QgsFeatureSink,
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QgsFields,
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QgsField,
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QgsGeometry,
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QgsSpatialIndex,
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QgsWkbTypes,
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QgsDistanceArea,
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QgsFeatureRequest,
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QgsFeature,
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QgsPointXY,
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QgsMessageLog,
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QgsProcessingUtils)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterNumber
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects, vector
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class RandomPointsAlongLines(QgisAlgorithm):
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VECTOR = 'VECTOR'
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POINT_NUMBER = 'POINT_NUMBER'
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MIN_DISTANCE = 'MIN_DISTANCE'
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OUTPUT = 'OUTPUT'
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def group(self):
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return self.tr('Vector creation tools')
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def __init__(self):
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super().__init__()
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self.addParameter(ParameterVector(self.VECTOR,
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self.tr('Input layer'), [dataobjects.TYPE_VECTOR_LINE]))
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self.addParameter(ParameterNumber(self.POINT_NUMBER,
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self.tr('Number of points'), 1, None, 1))
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self.addParameter(ParameterNumber(self.MIN_DISTANCE,
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self.tr('Minimum distance'), 0.0, None, 0.0))
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self.addOutput(OutputVector(self.OUTPUT, self.tr('Random points'), datatype=[dataobjects.TYPE_VECTOR_POINT]))
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def name(self):
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return 'randompointsalongline'
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def displayName(self):
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return self.tr('Random points along line')
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def processAlgorithm(self, parameters, context, feedback):
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layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.VECTOR), context)
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pointCount = float(self.getParameterValue(self.POINT_NUMBER))
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minDistance = float(self.getParameterValue(self.MIN_DISTANCE))
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fields = QgsFields()
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fields.append(QgsField('id', QVariant.Int, '', 10, 0))
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writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fields, QgsWkbTypes.Point, layer.crs(), context)
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nPoints = 0
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nIterations = 0
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maxIterations = pointCount * 200
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featureCount = layer.featureCount()
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total = 100.0 / pointCount if pointCount else 1
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index = QgsSpatialIndex()
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points = dict()
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da = QgsDistanceArea()
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request = QgsFeatureRequest()
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random.seed()
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while nIterations < maxIterations and nPoints < pointCount:
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# pick random feature
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fid = random.randint(0, featureCount - 1)
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f = next(layer.getFeatures(request.setFilterFid(fid).setSubsetOfAttributes([])))
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fGeom = f.geometry()
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if fGeom.isMultipart():
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lines = fGeom.asMultiPolyline()
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# pick random line
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lineId = random.randint(0, len(lines) - 1)
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vertices = lines[lineId]
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else:
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vertices = fGeom.asPolyline()
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# pick random segment
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if len(vertices) == 2:
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vid = 0
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else:
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vid = random.randint(0, len(vertices) - 2)
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startPoint = vertices[vid]
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endPoint = vertices[vid + 1]
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length = da.measureLine(startPoint, endPoint)
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dist = length * random.random()
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if dist > minDistance:
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d = dist / (length - dist)
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rx = (startPoint.x() + d * endPoint.x()) / (1 + d)
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ry = (startPoint.y() + d * endPoint.y()) / (1 + d)
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# generate random point
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pnt = QgsPointXY(rx, ry)
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geom = QgsGeometry.fromPoint(pnt)
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if vector.checkMinDistance(pnt, index, minDistance, points):
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f = QgsFeature(nPoints)
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f.initAttributes(1)
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f.setFields(fields)
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f.setAttribute('id', nPoints)
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f.setGeometry(geom)
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writer.addFeature(f, QgsFeatureSink.FastInsert)
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index.insertFeature(f)
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points[nPoints] = pnt
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nPoints += 1
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feedback.setProgress(int(nPoints * total))
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nIterations += 1
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if nPoints < pointCount:
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QgsMessageLog.logMessage(self.tr('Can not generate requested number of random points. '
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'Maximum number of attempts exceeded.'), self.tr('Processing'), QgsMessageLog.INFO)
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del writer
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