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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
141 lines
4.8 KiB
Python
141 lines
4.8 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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RasterLayerStatistics.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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from builtins import str
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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 math
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import codecs
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from qgis.core import (QgsApplication)
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterRaster
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from processing.core.outputs import OutputNumber
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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 RasterLayerStatistics(GeoAlgorithm):
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INPUT = 'INPUT'
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MIN = 'MIN'
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MAX = 'MAX'
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SUM = 'SUM'
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MEAN = 'MEAN'
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COUNT = 'COUNT'
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NO_DATA_COUNT = 'NO_DATA_COUNT'
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STD_DEV = 'STD_DEV'
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OUTPUT_HTML_FILE = 'OUTPUT_HTML_FILE'
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def icon(self):
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return QgsApplication.getThemeIcon("/providerQgis.svg")
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def svgIconPath(self):
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return QgsApplication.iconPath("providerQgis.svg")
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def group(self):
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return self.tr('Raster tools')
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def name(self):
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return 'rasterlayerstatistics'
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def displayName(self):
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return self.tr('Raster layer statistics')
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def defineCharacteristics(self):
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self.addParameter(ParameterRaster(self.INPUT, self.tr('Input layer')))
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self.addOutput(OutputHTML(self.OUTPUT_HTML_FILE, self.tr('Statistics')))
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self.addOutput(OutputNumber(self.MIN, self.tr('Minimum value')))
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self.addOutput(OutputNumber(self.MAX, self.tr('Maximum value')))
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self.addOutput(OutputNumber(self.SUM, self.tr('Sum')))
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self.addOutput(OutputNumber(self.MEAN, self.tr('Mean value')))
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self.addOutput(OutputNumber(self.COUNT, self.tr('valid cells count')))
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self.addOutput(OutputNumber(self.COUNT, self.tr('No-data cells count')))
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self.addOutput(OutputNumber(self.STD_DEV, self.tr('Standard deviation')))
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def processAlgorithm(self, context, feedback):
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outputFile = self.getOutputValue(self.OUTPUT_HTML_FILE)
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uri = self.getParameterValue(self.INPUT)
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(uri, context)
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values = raster.scanraster(layer, feedback)
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n = 0
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nodata = 0
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mean = 0
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M2 = 0
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sum = 0
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minvalue = None
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maxvalue = None
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for v in values:
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if v is not None:
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sum += v
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n = n + 1
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delta = v - mean
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mean = mean + delta / n
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M2 = M2 + delta * (v - mean)
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if minvalue is None:
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minvalue = v
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maxvalue = v
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else:
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minvalue = min(v, minvalue)
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maxvalue = max(v, maxvalue)
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else:
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nodata += 1
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variance = M2 / (n - 1)
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stddev = math.sqrt(variance)
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data = []
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data.append('Valid cells: ' + str(n))
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data.append('No-data cells: ' + str(nodata))
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data.append('Minimum value: ' + str(minvalue))
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data.append('Maximum value: ' + str(maxvalue))
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data.append('Sum: ' + str(sum))
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data.append('Mean value: ' + str(mean))
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data.append('Standard deviation: ' + str(stddev))
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self.createHTML(outputFile, data)
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self.setOutputValue(self.COUNT, n)
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self.setOutputValue(self.NO_DATA_COUNT, nodata)
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self.setOutputValue(self.MIN, minvalue)
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self.setOutputValue(self.MAX, maxvalue)
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self.setOutputValue(self.SUM, sum)
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self.setOutputValue(self.MEAN, mean)
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self.setOutputValue(self.STD_DEV, stddev)
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def createHTML(self, outputFile, algData):
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with codecs.open(outputFile, 'w', encoding='utf-8') as f:
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f.write('<html><head>')
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f.write('<meta http-equiv="Content-Type" content="text/html; \
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charset=utf-8" /></head><body>')
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for s in algData:
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f.write('<p>' + str(s) + '</p>')
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f.write('</body></html>')
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