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1e13d733c2
initAlgorithm() method This allows 2 benefits: - algorithms can be subclassed and have subclasses add additional parameters/outputs to the algorithm. With the previous approach of declaring parameters/outputs in the constructor, it's not possible to call virtual methods to add additional parameters/ outputs (since you can't call virtual methods from a constructor). - initAlgorithm takes a variant map argument, allowing the algorithm to dynamically adjust its declared parameters and outputs according to this configuration map. This potentially allows model algorithms which can be configured to have variable numbers of parameters and outputs at run time. E.g. a "router" algorithm which directs features to one of any number of output sinks depending on some user configured criteria.
138 lines
4.7 KiB
Python
138 lines
4.7 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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QgsProcessingUtils)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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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 raster
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class RasterLayerStatistics(QgisAlgorithm):
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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 group(self):
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return self.tr('Raster tools')
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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(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 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 processAlgorithm(self, parameters, 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 = 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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