# -*- coding: utf-8 -*- """ *************************************************************************** RandomExtract.py --------------------- Date : August 2012 Copyright : (C) 2012 by Victor Olaya Email : volayaf 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__ = 'Victor Olaya' __date__ = 'August 2012' __copyright__ = '(C) 2012, Victor Olaya' # This will get replaced with a git SHA1 when you do a git archive __revision__ = '$Format:%H$' import random from processing.core.GeoAlgorithm import GeoAlgorithm from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException from processing.core.parameters import ParameterSelection from processing.core.parameters import ParameterVector from processing.core.parameters import ParameterNumber from processing.core.outputs import OutputVector from processing.tools import dataobjects, vector class RandomExtract(GeoAlgorithm): INPUT = 'INPUT' OUTPUT = 'OUTPUT' METHOD = 'METHOD' NUMBER = 'NUMBER' def defineCharacteristics(self): self.name, self.i18n_name = self.trAlgorithm('Random extract') self.group, self.i18n_group = self.trAlgorithm('Vector selection tools') self.methods = [self.tr('Number of selected features'), self.tr('Percentage of selected features')] self.addParameter(ParameterVector(self.INPUT, self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_ANY])) self.addParameter(ParameterSelection(self.METHOD, self.tr('Method'), self.methods, 0)) self.addParameter(ParameterNumber(self.NUMBER, self.tr('Number/percentage of selected features'), 0, None, 10)) self.addOutput(OutputVector(self.OUTPUT, self.tr('Extracted (random)'))) def processAlgorithm(self, progress): filename = self.getParameterValue(self.INPUT) layer = dataobjects.getObjectFromUri(filename) method = self.getParameterValue(self.METHOD) features = vector.features(layer) featureCount = len(features) value = int(self.getParameterValue(self.NUMBER)) if method == 0: if value > featureCount: raise GeoAlgorithmExecutionException( self.tr('Selected number is greater than feature count. ' 'Choose a lower value and try again.')) else: if value > 100: raise GeoAlgorithmExecutionException( self.tr("Percentage can't be greater than 100. Set a " "different value and try again.")) value = int(round(value / 100.0000, 4) * featureCount) selran = random.sample(xrange(0, featureCount), value) writer = self.getOutputFromName(self.OUTPUT).getVectorWriter( layer.pendingFields().toList(), layer.wkbType(), layer.crs()) total = 100.0 / featureCount for i, feat in enumerate(features): if i in selran: writer.addFeature(feat) progress.setPercentage(int(i * total)) del writer