# -*- 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('<html><img src="' + plotFilename + '"/></html>')