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alexbruyalexbruy
committedMay 16, 2014
[processing] new tool: random points in layer bounds
Work done for Faunalia funded by Prof. António Mira (University of Évora, Portugal, Unidade de Biologia da Conservação) and Dr. Rosana Peixoto
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ltr-3_40archive/master_2
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‎python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

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from PointsFromPolygons import PointsFromPolygons
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from PointsFromLines import PointsFromLines
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from RandomPointsExtent import RandomPointsExtent
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from RandomPointsLayer import RandomPointsLayer
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# from VectorLayerHistogram import VectorLayerHistogram
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# from VectorLayerScatterplot import VectorLayerScatterplot
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RasterLayerStatistics(), PointsDisplacement(),
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ZonalStatistics(), PointsFromPolygons(),
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PointsFromLines(), RandomPointsExtent(),
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RandomPointsLayer(),
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# ------ raster ------
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# CreateConstantRaster(),
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# ------ graphics ------

‎python/plugins/processing/algs/qgis/RandomPointsLayer.py

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# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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RandomPointsLayer.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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__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 math
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import random
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from PyQt4.QtCore import *
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from qgis.core import *
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from processing import interface
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.ProcessingLog import ProcessingLog
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from processing.parameters.ParameterVector import ParameterVector
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from processing.parameters.ParameterNumber import ParameterNumber
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from processing.outputs.OutputVector import OutputVector
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from processing.tools import dataobjects, vector
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class RandomPointsLayer(GeoAlgorithm):
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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 defineCharacteristics(self):
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self.name = 'Random points in layer bounds'
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self.group = 'Vector creation tools'
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self.addParameter(ParameterVector(self.VECTOR,
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'Input layer',[ParameterVector.VECTOR_TYPE_POLYGON]))
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self.addParameter(
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ParameterNumber(self.POINT_NUMBER, 'Points number', 1, 9999999, 1))
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self.addParameter(ParameterNumber(
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self.MIN_DISTANCE, 'Minimum distance', 0.0, 9999999, 0.0))
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self.addOutput(OutputVector(self.OUTPUT, 'Random points'))
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def processAlgorithm(self, progress):
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layer = dataobjects.getObjectFromUri(
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self.getParameterValue(self.VECTOR))
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pointCount = int(self.getParameterValue(self.POINT_NUMBER))
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minDistance = float(self.getParameterValue(self.MIN_DISTANCE))
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bbox = layer.extent()
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extent = QgsGeometry().fromRect(bbox)
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idxLayer = vector.spatialindex(layer)
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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(
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fields, QGis.WKBPoint, layer.dataProvider().crs())
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nPoints = 0
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nIterations = 0
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maxIterations = pointCount * 200
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total = 100.0 / pointCount
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index = QgsSpatialIndex()
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points = dict()
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request = QgsFeatureRequest()
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while nIterations < maxIterations and nPoints < pointCount:
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rx = bbox.xMinimum() + bbox.width() * random.random()
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ry = bbox.yMinimum() + bbox.height() * random.random()
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pnt = QgsPoint(rx, ry)
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geom = QgsGeometry.fromPoint(pnt)
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ids = idxLayer.intersects(geom.buffer(5, 5).boundingBox())
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if len(ids) > 0 and \
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self.checkMinDistance(pnt, index, minDistance, points):
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for i in ids:
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f = layer.getFeatures(request.setFilterFid(i)).next()
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tmpGeom = QgsGeometry(f.geometry())
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if geom.within(tmpGeom):
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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)
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index.insertFeature(f)
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points[nPoints] = pnt
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nPoints += 1
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progress.setPercentage(int(nPoints * total))
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nIterations += 1
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if nPoints < pointCount:
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ProcessingLog.addToLog(
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ProcessingLog.LOG_INFO,
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'Can not generate requested number of random points. Maximum '
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'number of attempts exceeded.')
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del writer
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def checkMinDistance(self, point, index, distance, points):
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if distance == 0:
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return True
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neighbors = index.nearestNeighbor(point, 1)
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if len(neighbors) == 0:
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return True
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if neighbors[0] in points:
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np = points[neighbors[0]]
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if np.sqrDist(point) < (distance * distance):
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return False
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return True

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