QGIS/python/plugins/processing/algs/qgis/EquivalentNumField.py

# -*- coding: utf-8 -*-

"""
***************************************************************************
    EquivalentNumField.py
    ---------------------
    Date                 : August 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf 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__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsField,
                       QgsFeature,
                       QgsFeatureSink,
                       QgsApplication,
                       QgsProcessingUtils)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterTableField
from processing.core.outputs import OutputVector


class EquivalentNumField(QgisAlgorithm):

    INPUT = 'INPUT'
    OUTPUT = 'OUTPUT'
    FIELD = 'FIELD'

    def group(self):
        return self.tr('Vector table tools')

    def __init__(self):
        super().__init__()

    def initAlgorithm(self, config=None):
        self.addParameter(ParameterVector(self.INPUT,
                                          self.tr('Input layer')))
        self.addParameter(ParameterTableField(self.FIELD,
                                              self.tr('Class field'), self.INPUT))
        self.addOutput(OutputVector(self.OUTPUT, self.tr('Layer with index field')))

    def name(self):
        return 'adduniquevalueindexfield'

    def displayName(self):
        return self.tr('Add unique value index field')

    def processAlgorithm(self, parameters, context, feedback):
        fieldname = self.getParameterValue(self.FIELD)
        output = self.getOutputFromName(self.OUTPUT)
        vlayer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT), context)
        fieldindex = vlayer.fields().lookupField(fieldname)
        fields = vlayer.fields()
        fields.append(QgsField('NUM_FIELD', QVariant.Int))
        writer = output.getVectorWriter(fields, vlayer.wkbType(), vlayer.crs(), context)
        outFeat = QgsFeature()
        classes = {}

        features = QgsProcessingUtils.getFeatures(vlayer, context)
        total = 100.0 / vlayer.featureCount() if vlayer.featureCount() else 0
        for current, feature in enumerate(features):
            feedback.setProgress(int(current * total))
            inGeom = feature.geometry()
            outFeat.setGeometry(inGeom)
            atMap = feature.attributes()
            clazz = atMap[fieldindex]

            if clazz not in classes:
                classes[clazz] = len(list(classes.keys()))

            atMap.append(classes[clazz])
            outFeat.setAttributes(atMap)
            writer.addFeature(outFeat, QgsFeatureSink.FastInsert)

        del writer