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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.
135 lines
6.1 KiB
Python
135 lines
6.1 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ZonalStatistics.py
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---------------------
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Date : September 2016
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Copyright : (C) 2016 by Alexander Bruy
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Email : alexander dot bruy 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__ = 'Alexander Bruy'
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__date__ = 'September 2016'
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__copyright__ = '(C) 2016, Alexander Bruy'
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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 os
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from collections import OrderedDict
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from qgis.PyQt.QtGui import QIcon
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from qgis.analysis import QgsZonalStatistics
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from qgis.core import (QgsFeatureSink,
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QgsProcessing,
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QgsProcessingUtils,
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QgsProcessingParameterDefinition,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterRasterLayer,
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QgsProcessingParameterString,
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QgsProcessingParameterNumber,
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QgsProcessingParameterEnum,
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QgsProcessingOutputVectorLayer)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class ZonalStatistics(QgisAlgorithm):
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INPUT_RASTER = 'INPUT_RASTER'
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RASTER_BAND = 'RASTER_BAND'
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INPUT_VECTOR = 'INPUT_VECTOR'
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COLUMN_PREFIX = 'COLUMN_PREFIX'
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STATISTICS = 'STATS'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'zonalstats.png'))
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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.STATS = OrderedDict([(self.tr('Count'), QgsZonalStatistics.Count),
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(self.tr('Sum'), QgsZonalStatistics.Sum),
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(self.tr('Mean'), QgsZonalStatistics.Mean),
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(self.tr('Median'), QgsZonalStatistics.Median),
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(self.tr('Std. dev.'), QgsZonalStatistics.StDev),
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(self.tr('Min'), QgsZonalStatistics.Min),
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(self.tr('Max'), QgsZonalStatistics.Max),
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(self.tr('Range'), QgsZonalStatistics.Range),
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(self.tr('Minority'), QgsZonalStatistics.Minority),
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(self.tr('Majority (mode)'), QgsZonalStatistics.Majority),
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(self.tr('Variety'), QgsZonalStatistics.Variety),
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(self.tr('Variance'), QgsZonalStatistics.Variance),
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(self.tr('All'), QgsZonalStatistics.All)])
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self.addParameter(QgsProcessingParameterRasterLayer(self.INPUT_RASTER,
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self.tr('Raster layer')))
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self.addParameter(QgsProcessingParameterNumber(self.RASTER_BAND,
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self.tr('Raster band'),
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minValue=1, maxValue=999, defaultValue=1))
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT_VECTOR,
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self.tr('Vector layer containing zones'),
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[QgsProcessing.TypeVectorPolygon]))
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self.addParameter(QgsProcessingParameterString(self.COLUMN_PREFIX,
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self.tr('Output column prefix'), '_'))
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keys = list(self.STATS.keys())
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self.addParameter(QgsProcessingParameterEnum(self.STATISTICS,
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self.tr('Statistics to calculate'),
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keys,
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allowMultiple=True, defaultValue=[0, 1, 2]))
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self.addOutput(QgsProcessingOutputVectorLayer(self.INPUT_VECTOR,
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self.tr('Zonal statistics'),
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QgsProcessing.TypeVectorPolygon))
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self.bandNumber = None
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self.columnPrefix = None
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self.selectedStats = None
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self.vectorLayer = None
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self.rasterLayer = None
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def name(self):
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return 'zonalstatistics'
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def displayName(self):
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return self.tr('Zonal Statistics')
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def prepareAlgorithm(self, parameters, context, feedback):
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self.bandNumber = self.parameterAsInt(parameters, self.RASTER_BAND, context)
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self.columnPrefix = self.parameterAsString(parameters, self.COLUMN_PREFIX, context)
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st = self.parameterAsEnums(parameters, self.STATISTICS, context)
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keys = list(self.STATS.keys())
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self.selectedStats = 0
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for i in st:
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self.selectedStats |= self.STATS[keys[i]]
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self.vectorLayer = self.parameterAsVectorLayer(parameters, self.INPUT_VECTOR, context)
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self.rasterLayer = self.parameterAsRasterLayer(parameters, self.INPUT_RASTER, context)
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return True
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def processAlgorithm(self, parameters, context, feedback):
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zs = QgsZonalStatistics(self.vectorLayer,
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self.rasterLayer,
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self.columnPrefix,
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self.bandNumber,
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QgsZonalStatistics.Statistics(self.selectedStats))
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zs.calculateStatistics(feedback)
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return {self.INPUT_VECTOR: self.vectorLayer}
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