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b637c7fe22
This algorithm is NEVER safe to run in the background, because it directly modifies a layer in place. We should: - make a variant of this algorithm which returns a new layer AND - refactor the QgsZonalStats code to create a separate map of feature->stats, and then modify the existing Zonal Stats algorithm to apply these changes in a post processing step
149 lines
6.8 KiB
Python
149 lines
6.8 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 (QgsProcessing,
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QgsProcessingAlgorithm,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterRasterLayer,
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QgsProcessingParameterString,
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QgsProcessingParameterBand,
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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 analysis')
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def groupId(self):
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return 'rasteranalysis'
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def flags(self):
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return super().flags() | QgsProcessingAlgorithm.FlagNoThreading
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def __init__(self):
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super().__init__()
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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.raster_interface = None
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self.raster_crs = None
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self.raster_units_per_pixel_x = None
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self.raster_units_per_pixel_y = None
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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(QgsProcessingParameterBand(self.RASTER_BAND,
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self.tr('Raster band'),
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1,
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self.INPUT_RASTER))
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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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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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rasterLayer = self.parameterAsRasterLayer(parameters, self.INPUT_RASTER, context)
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self.raster_interface = rasterLayer.dataProvider().clone()
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self.raster_crs = rasterLayer.crs()
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self.raster_units_per_pixel_x = rasterLayer.rasterUnitsPerPixelX()
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self.raster_units_per_pixel_y = rasterLayer.rasterUnitsPerPixelY()
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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.raster_interface,
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self.raster_crs,
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self.raster_units_per_pixel_x,
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self.raster_units_per_pixel_y,
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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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