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[processing] Add Aggregate algorithm
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# -*- coding: utf-8 -*- | ||
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""" | ||
*************************************************************************** | ||
Aggregate.py | ||
--------------------- | ||
Date : February 2017 | ||
Copyright : (C) 2017 by Arnaud Morvan | ||
Email : arnaud dot morvan at camptocamp 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. * | ||
* * | ||
*************************************************************************** | ||
""" | ||
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__author__ = 'Arnaud Morvan' | ||
__date__ = 'February 2017' | ||
__copyright__ = '(C) 2017, Arnaud Morvan' | ||
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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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from qgis.core import ( | ||
QgsDistanceArea, | ||
QgsExpression, | ||
QgsExpressionContextUtils, | ||
QgsFeature, | ||
QgsFeatureSink, | ||
QgsField, | ||
QgsFields, | ||
QgsGeometry, | ||
QgsProcessingParameterDefinition, | ||
QgsProcessingParameterExpression, | ||
QgsProcessingParameterFeatureSink, | ||
QgsProcessingParameterFeatureSource, | ||
QgsProcessingException, | ||
QgsProcessingUtils, | ||
QgsWkbTypes, | ||
) | ||
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm | ||
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class Aggregate(QgisAlgorithm): | ||
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INPUT = 'INPUT' | ||
GROUP_BY = 'GROUP_BY' | ||
AGGREGATES = 'AGGREGATES' | ||
DISSOLVE = 'DISSOLVE' | ||
OUTPUT = 'OUTPUT' | ||
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def group(self): | ||
return self.tr('Vector geometry tools') | ||
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def name(self): | ||
return 'aggregate' | ||
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def displayName(self): | ||
return self.tr('Aggregate') | ||
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def initAlgorithm(self, config=None): | ||
self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT, | ||
self.tr('Input layer'))) | ||
self.addParameter(QgsProcessingParameterExpression(self.GROUP_BY, | ||
self.tr('Group by expression (NULL to group all features)'), | ||
defaultValue='NULL', | ||
optional=False, | ||
parentLayerParameterName=self.INPUT)) | ||
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class ParameterAggregates(QgsProcessingParameterDefinition): | ||
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def __init__(self, name, description, parentLayerParameterName='INPUT'): | ||
super().__init__(name, description) | ||
self._parentLayerParameter = parentLayerParameterName | ||
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def type(self): | ||
return 'aggregates' | ||
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def checkValueIsAcceptable(self, value, context=None): | ||
if not isinstance(value, list): | ||
return False | ||
for field_def in value: | ||
if not isinstance(field_def, dict): | ||
return False | ||
if not field_def.get('input', False): | ||
return False | ||
if not field_def.get('aggregate', False): | ||
return False | ||
if not field_def.get('name', False): | ||
return False | ||
if not field_def.get('type', False): | ||
return False | ||
return True | ||
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def valueAsPythonString(self, value, context): | ||
return str(value) | ||
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def asScriptCode(self): | ||
raise NotImplementedError() | ||
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@classmethod | ||
def fromScriptCode(cls, name, description, isOptional, definition): | ||
raise NotImplementedError() | ||
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def parentLayerParameter(self): | ||
return self._parentLayerParameter | ||
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self.addParameter(ParameterAggregates(self.AGGREGATES, | ||
description=self.tr('Aggregates'))) | ||
self.parameterDefinition(self.AGGREGATES).setMetadata({ | ||
'widget_wrapper': 'processing.algs.qgis.ui.AggregatesPanel.AggregatesWidgetWrapper' | ||
}) | ||
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, | ||
self.tr('Aggregated'))) | ||
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def parameterAsAggregates(self, parameters, name, context): | ||
return parameters[name] | ||
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def prepareAlgorithm(self, parameters, context, feedback): | ||
source = self.parameterAsSource(parameters, self.INPUT, context) | ||
group_by = self.parameterAsExpression(parameters, self.GROUP_BY, context) | ||
aggregates = self.parameterAsAggregates(parameters, self.AGGREGATES, context) | ||
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da = QgsDistanceArea() | ||
da.setSourceCrs(source.sourceCrs()) | ||
da.setEllipsoid(context.project().ellipsoid()) | ||
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self.source = source | ||
self.group_by = group_by | ||
self.group_by_expr = self.createExpression(group_by, da, context) | ||
self.geometry_expr = self.createExpression('collect($geometry, {})'.format(group_by), da, context) | ||
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self.fields = QgsFields() | ||
self.fields_expr = [] | ||
for field_def in aggregates: | ||
self.fields.append(QgsField(name=field_def['name'], | ||
type=field_def['type'], | ||
typeName="", | ||
len=field_def['length'], | ||
prec=field_def['precision'])) | ||
aggregate = field_def['aggregate'] | ||
if aggregate == 'first_value': | ||
expression = field_def['input'] | ||
elif aggregate == 'concatenate': | ||
expression = ('{}({}, {}, {}, \'{}\')' | ||
.format(field_def['aggregate'], | ||
field_def['input'], | ||
group_by, | ||
'TRUE', | ||
field_def['delimiter'])) | ||
else: | ||
expression = '{}({}, {})'.format(field_def['aggregate'], | ||
field_def['input'], | ||
group_by) | ||
expr = self.createExpression(expression, da, context) | ||
self.fields_expr.append(expr) | ||
return True | ||
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def processAlgorithm(self, parameters, context, feedback): | ||
expr_context = self.createExpressionContext(parameters, context) | ||
self.group_by_expr.prepare(expr_context) | ||
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# Group features in memory layers | ||
source = self.source | ||
count = self.source.featureCount() | ||
if count: | ||
progress_step = 50.0 / count | ||
current = 0 | ||
groups = {} | ||
keys = [] # We need deterministic order for the tests | ||
feature = QgsFeature() | ||
for feature in self.source.getFeatures(): | ||
expr_context.setFeature(feature) | ||
group_by_value = self.evaluateExpression(self.group_by_expr, expr_context) | ||
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# Get an hashable key for the dict | ||
key = group_by_value | ||
if isinstance(key, list): | ||
key = tuple(key) | ||
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group = groups.get(key, None) | ||
if group is None: | ||
sink, id = QgsProcessingUtils.createFeatureSink( | ||
'memory:', | ||
context, | ||
source.fields(), | ||
source.wkbType(), | ||
source.sourceCrs()) | ||
layer = QgsProcessingUtils.mapLayerFromString(id, context) | ||
group = { | ||
'sink': sink, | ||
'layer': layer, | ||
'feature': feature | ||
} | ||
groups[key] = group | ||
keys.append(key) | ||
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group['sink'].addFeature(feature, QgsFeatureSink.FastInsert) | ||
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current += 1 | ||
feedback.setProgress(int(current * progress_step)) | ||
if feedback.isCanceled(): | ||
return | ||
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(sink, dest_id) = self.parameterAsSink(parameters, | ||
self.OUTPUT, | ||
context, | ||
self.fields, | ||
QgsWkbTypes.multiType(source.wkbType()), | ||
source.sourceCrs()) | ||
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# Calculate aggregates on memory layers | ||
if len(keys): | ||
progress_step = 50.0 / len(keys) | ||
for current, key in enumerate(keys): | ||
group = groups[key] | ||
expr_context = self.createExpressionContext(parameters, context) | ||
expr_context.appendScope(QgsExpressionContextUtils.layerScope(group['layer'])) | ||
expr_context.setFeature(group['feature']) | ||
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geometry = self.evaluateExpression(self.geometry_expr, expr_context) | ||
if geometry is not None and not geometry.isEmpty(): | ||
geometry = QgsGeometry.unaryUnion(geometry.asGeometryCollection()) | ||
if geometry.isEmpty(): | ||
raise QgsProcessingException( | ||
'Impossible to combine geometries for {} = {}' | ||
.format(self.group_by, group_by_value)) | ||
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attrs = [] | ||
for fields_expr in self.fields_expr: | ||
attrs.append(self.evaluateExpression(fields_expr, expr_context)) | ||
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# Write output feature | ||
outFeat = QgsFeature() | ||
if geometry is not None: | ||
outFeat.setGeometry(geometry) | ||
outFeat.setAttributes(attrs) | ||
sink.addFeature(outFeat, QgsFeatureSink.FastInsert) | ||
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feedback.setProgress(50 + int(current * progress_step)) | ||
if feedback.isCanceled(): | ||
return | ||
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return {self.OUTPUT: dest_id} | ||
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def createExpression(self, text, da, context): | ||
expr = QgsExpression(text) | ||
expr.setGeomCalculator(da) | ||
expr.setDistanceUnits(context.project().distanceUnits()) | ||
expr.setAreaUnits(context.project().areaUnits()) | ||
if expr.hasParserError(): | ||
raise QgsProcessingException( | ||
self.tr(u'Parser error in expression "{}": {}') | ||
.format(text, expr.parserErrorString())) | ||
return expr | ||
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def evaluateExpression(self, expr, context): | ||
value = expr.evaluate(context) | ||
if expr.hasEvalError(): | ||
raise QgsProcessingException( | ||
self.tr(u'Evaluation error in expression "{}": {}') | ||
.format(expr.expression(), expr.evalErrorString())) | ||
return value |
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