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RasterSampling.py
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RasterSampling.py
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# -*- coding: utf-8 -*-
"""
***************************************************************************
RasterSampling.py
-----------------------
Date : July 2018
Copyright : (C) 2018 by Matteo Ghetta
Email : matteo dot ghetta at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
__author__ = 'Matteo Ghetta'
__date__ = 'July 2018'
__copyright__ = '(C) 2018, Matteo Ghetta'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'
import os
from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsApplication,
QgsField,
QgsFeatureSink,
QgsRaster,
QgsProcessing,
QgsProcessingParameterRasterLayer,
QgsProcessingParameterString,
QgsProcessingParameterDefinition,
QgsCoordinateTransform,
QgsFields,
QgsProcessingUtils,
QgsProcessingException,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterFeatureSink)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
class RasterSampling(QgisAlgorithm):
INPUT = 'INPUT'
RASTERCOPY = 'RASTERCOPY'
COLUMN_PREFIX = 'COLUMN_PREFIX'
OUTPUT = 'OUTPUT'
def name(self):
return 'rastersampling'
def displayName(self):
return self.tr('Sample Raster Values')
def group(self):
return self.tr('Raster analysis')
def groupId(self):
return 'rasteranalysis'
def __init__(self):
super().__init__()
def initAlgorithm(self, config=None):
self.addParameter(
QgsProcessingParameterFeatureSource(
self.INPUT,
self.tr('Input Point Layer'),
[QgsProcessing.TypeVectorPoint]
)
)
self.addParameter(
QgsProcessingParameterRasterLayer(
self.RASTERCOPY,
self.tr('Raster Layer to sample'),
)
)
columnPrefix = QgsProcessingParameterString(
self.COLUMN_PREFIX,
self.tr('Output column prefix'), 'rvalue'
)
columnPrefix.setFlags(columnPrefix.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
self.addParameter(columnPrefix)
self.addParameter(
QgsProcessingParameterFeatureSink(
self.OUTPUT,
self.tr('Sampled Points')
)
)
def processAlgorithm(self, parameters, context, feedback):
source = self.parameterAsSource(
parameters,
self.INPUT,
context
)
sampled_raster = self.parameterAsRasterLayer(
parameters,
self.RASTERCOPY,
context
)
columnPrefix = self.parameterAsString(
parameters,
self.COLUMN_PREFIX,
context
)
if source is None:
raise QgsProcessingException(self.invalidSourceError(parameters, self.INPUT))
source_fields = source.fields()
raster_fields = QgsFields()
# append field to vector as columnPrefix_bandCount
for b in range(sampled_raster.bandCount()):
raster_fields.append(QgsField(
columnPrefix + str('_{}'.format(b + 1)), QVariant.Double
)
)
# combine all the vector fields
out_fields = QgsProcessingUtils.combineFields(source_fields, raster_fields)
(sink, dest_id) = self.parameterAsSink(
parameters,
self.OUTPUT,
context,
out_fields,
source.wkbType(),
source.sourceCrs()
)
if sink is None:
raise QgsProcessingException(self.invalidSinkError(parameters, self.OUTPUT))
total = 100.0 / source.featureCount() if source.featureCount() else 0
features = source.getFeatures()
# create the coordinates transformation context
ct = QgsCoordinateTransform(source.sourceCrs(), sampled_raster.crs(), context.transformContext())
for n, i in enumerate(source.getFeatures()):
attrs = i.attributes()
if i.geometry().isMultipart():
raise QgsProcessingException(self.tr('''Impossible to sample data
of a Multipart layer. Please use the Multipart to single part
algorithm to transform the layer.'''))
# get the feature geometry as point
point = i.geometry().asPoint()
# reproject to raster crs
try:
point = ct.transform(point)
except QgsCsException:
for b in range(sampled_raster.bandCount()):
attrs.append(None)
i.setAttributes(attrs)
sink.addFeature(i, QgsFeatureSink.FastInsert)
feedback.setProgress(int(n * total))
feedback.reportError(self.tr('Could not reproject feature {} to raster CRS').format(i.id()))
continue
if sampled_raster.bandCount() > 1:
for b in range(sampled_raster.bandCount()):
attrs.append(
sampled_raster.dataProvider().identify(
point,
QgsRaster.IdentifyFormatValue).results()[b + 1]
)
attrs.append(
sampled_raster.dataProvider().identify(
point,
QgsRaster.IdentifyFormatValue).results()[1]
)
i.setAttributes(attrs)
sink.addFeature(i, QgsFeatureSink.FastInsert)
feedback.setProgress(int(n * total))
return {self.OUTPUT: dest_id}