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92 lines
3.2 KiB
Python
92 lines
3.2 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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RasterLayerHistogram.py
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---------------------
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Date : January 2013
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Copyright : (C) 2013 by Victor Olaya
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Email : volayaf 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__ = 'Victor Olaya'
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__date__ = 'January 2013'
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__copyright__ = '(C) 2013, Victor Olaya'
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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 matplotlib.pyplot as plt
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import matplotlib.pylab as lab
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from PyQt4.QtCore import QVariant
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from qgis.core import QgsField
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterNumber
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from processing.core.parameters import ParameterRaster
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from processing.core.outputs import OutputTable
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from processing.core.outputs import OutputHTML
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from processing.tools import dataobjects
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from processing.tools import raster
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class RasterLayerHistogram(GeoAlgorithm):
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INPUT = 'INPUT'
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PLOT = 'PLOT'
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TABLE = 'TABLE'
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BINS = 'BINS'
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def defineCharacteristics(self):
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self.name = 'Raster layer histogram'
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self.group = 'Graphics'
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self.addParameter(ParameterRaster(self.INPUT,
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self.tr('Input layer')))
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self.addParameter(ParameterNumber(self.BINS,
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self.tr('Number of bins'), 2, None, 10))
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self.addOutput(OutputHTML(self.PLOT, self.tr('Histogram')))
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self.addOutput(OutputTable(self.TABLE, self.tr('Table')))
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def processAlgorithm(self, progress):
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layer = dataobjects.getObjectFromUri(
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self.getParameterValue(self.INPUT))
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nbins = self.getParameterValue(self.BINS)
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outputplot = self.getOutputValue(self.PLOT)
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outputtable = self.getOutputFromName(self.TABLE)
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values = raster.scanraster(layer, progress)
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# ALERT: this is potentially blocking if the layer is too big
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plt.close()
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valueslist = []
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for v in values:
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if v is not None:
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valueslist.append(v)
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(n, bins, values) = plt.hist(valueslist, nbins)
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fields = [QgsField('CENTER_VALUE', QVariant.Double),
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QgsField('NUM_ELEM', QVariant.Double)]
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writer = outputtable.getTableWriter(fields)
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for i in xrange(len(values)):
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writer.addRecord([str(bins[i]) + '-' + str(bins[i + 1]), n[i]])
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plotFilename = outputplot + '.png'
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lab.savefig(plotFilename)
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f = open(outputplot, 'w')
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f.write('<html><img src="' + plotFilename + '"/></html>')
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f.close()
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