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b1cadb1822
have specific icons, instead of generic qgis icon We consider these 'top level' algorithms, and using the standard algorithm icon should help reflect this and differentiate them from 3rd party algorithms.
171 lines
6.9 KiB
Python
171 lines
6.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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FieldsCalculator.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf 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__ = 'Victor Olaya'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya'
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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.PyQt.QtCore import QVariant
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from qgis.core import (QgsExpression,
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QgsExpressionContext,
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QgsExpressionContextUtils,
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QgsFeature,
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QgsFeatureSink,
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QgsField,
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QgsDistanceArea,
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QgsProject,
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QgsApplication,
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QgsProcessingUtils)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterString
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from processing.core.parameters import ParameterNumber
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from processing.core.parameters import ParameterBoolean
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from processing.core.parameters import ParameterSelection
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from processing.core.outputs import OutputVector
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from .ui.FieldsCalculatorDialog import FieldsCalculatorDialog
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class FieldsCalculator(QgisAlgorithm):
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INPUT_LAYER = 'INPUT_LAYER'
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NEW_FIELD = 'NEW_FIELD'
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FIELD_NAME = 'FIELD_NAME'
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FIELD_TYPE = 'FIELD_TYPE'
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FIELD_LENGTH = 'FIELD_LENGTH'
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FIELD_PRECISION = 'FIELD_PRECISION'
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FORMULA = 'FORMULA'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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TYPES = [QVariant.Double, QVariant.Int, QVariant.String, QVariant.Date]
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def group(self):
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return self.tr('Vector table tools')
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def __init__(self):
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super().__init__()
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self.type_names = [self.tr('Float'),
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self.tr('Integer'),
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self.tr('String'),
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self.tr('Date')]
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self.addParameter(ParameterVector(self.INPUT_LAYER,
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self.tr('Input layer')))
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self.addParameter(ParameterString(self.FIELD_NAME,
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self.tr('Result field name')))
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self.addParameter(ParameterSelection(self.FIELD_TYPE,
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self.tr('Field type'), self.type_names))
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self.addParameter(ParameterNumber(self.FIELD_LENGTH,
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self.tr('Field length'), 1, 255, 10))
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self.addParameter(ParameterNumber(self.FIELD_PRECISION,
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self.tr('Field precision'), 0, 15, 3))
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self.addParameter(ParameterBoolean(self.NEW_FIELD,
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self.tr('Create new field'), True))
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self.addParameter(ParameterString(self.FORMULA, self.tr('Formula')))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Calculated')))
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def name(self):
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return 'fieldcalculator'
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def displayName(self):
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return self.tr('Field calculator')
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def processAlgorithm(self, parameters, context, feedback):
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layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)
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fieldName = self.getParameterValue(self.FIELD_NAME)
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fieldType = self.TYPES[self.getParameterValue(self.FIELD_TYPE)]
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width = self.getParameterValue(self.FIELD_LENGTH)
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precision = self.getParameterValue(self.FIELD_PRECISION)
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newField = self.getParameterValue(self.NEW_FIELD)
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formula = self.getParameterValue(self.FORMULA)
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output = self.getOutputFromName(self.OUTPUT_LAYER)
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fields = layer.fields()
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if newField:
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fields.append(QgsField(fieldName, fieldType, '', width, precision))
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writer = output.getVectorWriter(fields, layer.wkbType(), layer.crs(), context)
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exp = QgsExpression(formula)
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da = QgsDistanceArea()
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da.setSourceCrs(layer.crs())
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da.setEllipsoid(QgsProject.instance().ellipsoid())
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exp.setGeomCalculator(da)
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exp.setDistanceUnits(QgsProject.instance().distanceUnits())
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exp.setAreaUnits(QgsProject.instance().areaUnits())
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exp_context = QgsExpressionContext(QgsExpressionContextUtils.globalProjectLayerScopes(layer))
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if not exp.prepare(exp_context):
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raise GeoAlgorithmExecutionException(
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self.tr('Evaluation error: {0}').format(exp.evalErrorString()))
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outFeature = QgsFeature()
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outFeature.initAttributes(len(fields))
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outFeature.setFields(fields)
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error = ''
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calculationSuccess = True
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features = QgsProcessingUtils.getFeatures(layer, context)
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total = 100.0 / layer.featureCount() if layer.featureCount() else 0
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rownum = 1
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for current, f in enumerate(features):
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rownum = current + 1
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exp_context.setFeature(f)
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exp_context.lastScope().setVariable("row_number", rownum)
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value = exp.evaluate(exp_context)
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if exp.hasEvalError():
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calculationSuccess = False
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error = exp.evalErrorString()
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break
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else:
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outFeature.setGeometry(f.geometry())
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for fld in f.fields():
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outFeature[fld.name()] = f[fld.name()]
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outFeature[fieldName] = value
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writer.addFeature(outFeature, QgsFeatureSink.FastInsert)
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feedback.setProgress(int(current * total))
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del writer
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if not calculationSuccess:
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raise GeoAlgorithmExecutionException(
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self.tr('An error occurred while evaluating the calculation '
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'string:\n{0}').format(error))
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def checkParameterValues(self, parameters, context):
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newField = self.getParameterValue(self.NEW_FIELD)
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fieldName = self.getParameterValue(self.FIELD_NAME).strip()
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if newField and len(fieldName) == 0:
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return self.tr('Field name is not set. Please enter a field name')
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return super(FieldsCalculator, self).checkParameterValues(parameters, context)
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def createCustomParametersWidget(self, parent):
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return FieldsCalculatorDialog(self)
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