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"""
***************************************************************************
Dissolve.py
---------------------
Date : Janaury 2015
Copyright : (C) 2015 by Giovanni Manghi
Email : giovanni dot manghi at naturalgis dot pt
***************************************************************************
* *
* 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__ = "Giovanni Manghi"
__date__ = "January 2015"
__copyright__ = "(C) 2015, Giovanni Manghi"
from qgis.core import (
QgsProcessingException,
QgsProcessingParameterDefinition,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterField,
QgsProcessingParameterString,
QgsProcessingParameterBoolean,
QgsProcessingParameterVectorDestination,
)
from processing.algs.gdal.GdalAlgorithm import GdalAlgorithm
from processing.algs.gdal.GdalUtils import GdalUtils
class Dissolve(GdalAlgorithm):
INPUT = "INPUT"
FIELD = "FIELD"
GEOMETRY = "GEOMETRY"
EXPLODE_COLLECTIONS = "EXPLODE_COLLECTIONS"
KEEP_ATTRIBUTES = "KEEP_ATTRIBUTES"
COUNT_FEATURES = "COUNT_FEATURES"
COMPUTE_AREA = "COMPUTE_AREA"
COMPUTE_STATISTICS = "COMPUTE_STATISTICS"
STATISTICS_ATTRIBUTE = "STATISTICS_ATTRIBUTE"
OPTIONS = "OPTIONS"
OUTPUT = "OUTPUT"
def __init__(self):
super().__init__()
def initAlgorithm(self, config=None):
self.addParameter(
QgsProcessingParameterFeatureSource(self.INPUT, self.tr("Input layer"))
)
self.addParameter(
QgsProcessingParameterField(
self.FIELD,
self.tr("Dissolve field"),
None,
self.INPUT,
QgsProcessingParameterField.DataType.Any,
optional=True,
)
)
self.addParameter(
QgsProcessingParameterString(
self.GEOMETRY, self.tr("Geometry column name"), defaultValue="geometry"
)
)
params = [
QgsProcessingParameterBoolean(
self.EXPLODE_COLLECTIONS,
self.tr(
"Produce one feature for each geometry in any kind of geometry collection in the source file"
),
defaultValue=False,
),
QgsProcessingParameterBoolean(
self.KEEP_ATTRIBUTES,
self.tr("Keep input attributes"),
defaultValue=False,
),
QgsProcessingParameterBoolean(
self.COUNT_FEATURES,
self.tr("Count dissolved features"),
defaultValue=False,
),
QgsProcessingParameterBoolean(
self.COMPUTE_AREA,
self.tr("Compute area and perimeter of dissolved features"),
defaultValue=False,
),
QgsProcessingParameterBoolean(
self.COMPUTE_STATISTICS,
self.tr("Compute min/max/sum/mean for attribute"),
defaultValue=False,
),
QgsProcessingParameterField(
self.STATISTICS_ATTRIBUTE,
self.tr("Numeric attribute to calculate statistics on"),
None,
self.INPUT,
QgsProcessingParameterField.DataType.Numeric,
optional=True,
),
QgsProcessingParameterString(
self.OPTIONS,
self.tr("Additional creation options"),
defaultValue="",
optional=True,
),
]
for param in params:
param.setFlags(
param.flags() | QgsProcessingParameterDefinition.Flag.FlagAdvanced
)
self.addParameter(param)
self.addParameter(
QgsProcessingParameterVectorDestination(self.OUTPUT, self.tr("Dissolved"))
)
def name(self):
return "dissolve"
def displayName(self):
return self.tr("Dissolve")
def group(self):
return self.tr("Vector geoprocessing")
def groupId(self):
return "vectorgeoprocessing"
def commandName(self):
return "ogr2ogr"
def getConsoleCommands(self, parameters, context, feedback, executing=True):
source = self.parameterAsSource(parameters, self.INPUT, context)
if source is None:
raise QgsProcessingException(
self.invalidSourceError(parameters, self.INPUT)
)
fields = source.fields()
input_details = self.getOgrCompatibleSource(
self.INPUT, parameters, context, feedback, executing
)
geometry = self.parameterAsString(parameters, self.GEOMETRY, context)
fieldName = self.parameterAsString(parameters, self.FIELD, context)
options = self.parameterAsString(parameters, self.OPTIONS, context)
outFile = self.parameterAsOutputLayer(parameters, self.OUTPUT, context)
self.setOutputValue(self.OUTPUT, outFile)
output_details = GdalUtils.gdal_connection_details_from_uri(outFile, context)
other_fields_exist = any(True for f in fields if f.name() != geometry)
other_fields = ",*" if other_fields_exist else ""
arguments = [
output_details.connection_string,
input_details.connection_string,
"-nlt PROMOTE_TO_MULTI",
"-dialect",
"sqlite",
"-sql",
]
tokens = []
if self.parameterAsBoolean(parameters, self.COUNT_FEATURES, context):
tokens.append(f"COUNT({geometry}) AS count")
if self.parameterAsBoolean(parameters, self.COMPUTE_AREA, context):
tokens.append(
"SUM(ST_Area({0})) AS area, ST_Perimeter(ST_Union({0})) AS perimeter".format(
geometry
)
)
statsField = self.parameterAsString(
parameters, self.STATISTICS_ATTRIBUTE, context
)
if statsField and self.parameterAsBoolean(
parameters, self.COMPUTE_STATISTICS, context
):
tokens.append(
'SUM("{0}") AS sum, MIN("{0}") AS min, MAX("{0}") AS max, AVG("{0}") AS avg'.format(
statsField
)
)
params = ",".join(tokens)
if params:
params = ", " + params
group_by = ""
if fieldName:
group_by = f' GROUP BY "{fieldName}"'
if self.parameterAsBoolean(parameters, self.KEEP_ATTRIBUTES, context):
sql = f'SELECT ST_Union({geometry}) AS {geometry}{other_fields}{params} FROM "{input_details.layer_name}"{group_by}'
else:
sql = 'SELECT ST_Union({}) AS {}{}{} FROM "{}"{}'.format(
geometry,
geometry,
f', "{fieldName}"' if fieldName else "",
params,
input_details.layer_name,
group_by,
)
arguments.append(sql)
if self.parameterAsBoolean(parameters, self.EXPLODE_COLLECTIONS, context):
arguments.append("-explodecollections")
if input_details.open_options:
arguments.extend(input_details.open_options_as_arguments())
if input_details.credential_options:
arguments.extend(input_details.credential_options_as_arguments())
if options:
arguments.append(options)
if output_details.format:
arguments.append(f"-f {output_details.format}")
return [self.commandName(), GdalUtils.escapeAndJoin(arguments)]
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