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101 lines
3.9 KiB
Python
101 lines
3.9 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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import warnings
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from qgis.core import (QgsProcessingParameterRasterLayer,
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QgsProcessingParameterBand,
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QgsProcessingParameterNumber,
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QgsProcessingParameterFileDestination,
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QgsProcessingException)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.tools import raster
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from qgis.PyQt.QtCore import QCoreApplication
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class RasterLayerHistogram(QgisAlgorithm):
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INPUT = 'INPUT'
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BINS = 'BINS'
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OUTPUT = 'OUTPUT'
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BAND = 'BAND'
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def group(self):
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return self.tr('Graphics')
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def groupId(self):
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return 'graphics'
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(QgsProcessingParameterRasterLayer(self.INPUT,
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self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterBand(self.BAND,
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self.tr('Band number'),
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1,
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self.INPUT))
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self.addParameter(QgsProcessingParameterNumber(self.BINS,
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self.tr('number of bins'), minValue=2, defaultValue=10))
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self.addParameter(QgsProcessingParameterFileDestination(self.OUTPUT, self.tr('Histogram'), self.tr('HTML files (*.html)')))
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def name(self):
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return 'rasterlayerhistogram'
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def displayName(self):
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return self.tr('Raster layer histogram')
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def processAlgorithm(self, parameters, context, feedback):
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try:
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# importing plotly throws Python warnings from within the library - filter these out
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with warnings.catch_warnings():
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warnings.filterwarnings("ignore", category=ResourceWarning)
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warnings.filterwarnings("ignore", category=ImportWarning)
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import plotly as plt
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import plotly.graph_objs as go
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except ImportError:
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raise QgsProcessingException(QCoreApplication.translate('RasterLayerHistogram', 'This algorithm requires the Python “plotly” library. Please install this library and try again.'))
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layer = self.parameterAsRasterLayer(parameters, self.INPUT, context)
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band = self.parameterAsInt(parameters, self.BAND, context)
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nbins = self.parameterAsInt(parameters, self.BINS, context)
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output = self.parameterAsFileOutput(parameters, self.OUTPUT, context)
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# ALERT: this is potentially blocking if the layer is too big
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values = raster.scanraster(layer, feedback, band)
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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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data = [go.Histogram(x=valueslist,
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nbinsx=nbins)]
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plt.offline.plot(data, filename=output, auto_open=False)
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return {self.OUTPUT: output}
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