# -*- coding: utf-8 -*- """ *************************************************************************** RasterLayerHistogram.py --------------------- Date : January 2013 Copyright : (C) 2013 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. * * * *************************************************************************** """ from builtins import str from builtins import range __author__ = 'Victor Olaya' __date__ = 'January 2013' __copyright__ = '(C) 2013, Victor Olaya' # This will get replaced with a git SHA1 when you do a git archive __revision__ = '$Format:%H$' import matplotlib.pyplot as plt import matplotlib.pylab as lab from qgis.PyQt.QtCore import QVariant from qgis.core import QgsField from processing.core.GeoAlgorithm import GeoAlgorithm from processing.core.parameters import ParameterNumber from processing.core.parameters import ParameterRaster from processing.core.outputs import OutputTable from processing.core.outputs import OutputHTML from processing.tools import dataobjects from processing.tools import raster class RasterLayerHistogram(GeoAlgorithm): INPUT = 'INPUT' PLOT = 'PLOT' TABLE = 'TABLE' BINS = 'BINS' def defineCharacteristics(self): self.name, self.i18n_name = self.trAlgorithm('Raster layer histogram') self.group, self.i18n_group = self.trAlgorithm('Graphics') self.addParameter(ParameterRaster(self.INPUT, self.tr('Input layer'))) self.addParameter(ParameterNumber(self.BINS, self.tr('Number of bins'), 2, None, 10)) self.addOutput(OutputHTML(self.PLOT, self.tr('Histogram'))) self.addOutput(OutputTable(self.TABLE, self.tr('Table'))) def processAlgorithm(self, progress): layer = dataobjects.getObjectFromUri( self.getParameterValue(self.INPUT)) nbins = self.getParameterValue(self.BINS) outputplot = self.getOutputValue(self.PLOT) outputtable = self.getOutputFromName(self.TABLE) values = raster.scanraster(layer, progress) # ALERT: this is potentially blocking if the layer is too big plt.close() valueslist = [] for v in values: if v is not None: valueslist.append(v) (n, bins, values) = plt.hist(valueslist, nbins) fields = [QgsField('CENTER_VALUE', QVariant.Double), QgsField('NUM_ELEM', QVariant.Double)] writer = outputtable.getTableWriter(fields) for i in range(len(values)): writer.addRecord([str(bins[i]) + '-' + str(bins[i + 1]), n[i]]) plotFilename = outputplot + '.png' lab.savefig(plotFilename) with open(outputplot, 'w') as f: f.write('')