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

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

"""
***************************************************************************
    IdwInterpolation.py
    ---------------------
    Date                 : October 2016
    Copyright            : (C) 2016 by Alexander Bruy
    Email                : alexander dot bruy 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__ = 'Alexander Bruy'
__date__ = 'October 2016'
__copyright__ = '(C) 2016, Alexander Bruy'

# 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.core import (QgsRectangle,
                       QgsProcessingUtils,
                       QgsProcessingParameterDefinition,
                       QgsProcessingParameterNumber,
                       QgsProcessingParameterExtent,
                       QgsProcessingParameterRasterDestination,
                       QgsProcessingException)
from qgis.analysis import (QgsInterpolator,
                           QgsIDWInterpolator,
                           QgsGridFileWriter)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class ParameterInterpolationData(QgsProcessingParameterDefinition):

    def __init__(self, name='', description=''):
        super().__init__(name, description)
        self.setMetadata({
            'widget_wrapper': 'processing.algs.qgis.ui.InterpolationDataWidget.InterpolationDataWidgetWrapper'
        })

    def type(self):
        return 'idw_interpolation_data'

    def clone(self):
        return ParameterInterpolationData(self.name(), self.description())

    @staticmethod
    def parseValue(value):
        if value is None:
            return None

        if value == '':
            return None

        if isinstance(value, str):
            return value if value != '' else None
        else:
            return ParameterInterpolationData.dataToString(value)

    @staticmethod
    def dataToString(data):
        s = ''
        for c in data:
            s += '{}, {}, {:d}, {:d};'.format(c[0],
                                              c[1],
                                              c[2],
                                              c[3])
        return s[:-1]


class IdwInterpolation(QgisAlgorithm):

    INTERPOLATION_DATA = 'INTERPOLATION_DATA'
    DISTANCE_COEFFICIENT = 'DISTANCE_COEFFICIENT'
    COLUMNS = 'COLUMNS'
    ROWS = 'ROWS'
    EXTENT = 'EXTENT'
    OUTPUT = 'OUTPUT'

    def icon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'interpolation.png'))

    def group(self):
        return self.tr('Interpolation')

    def groupId(self):
        return 'interpolation'

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

    def initAlgorithm(self, config=None):

        self.addParameter(ParameterInterpolationData(self.INTERPOLATION_DATA,
                                                     self.tr('Input layer(s)')))
        self.addParameter(QgsProcessingParameterNumber(self.DISTANCE_COEFFICIENT,
                                                       self.tr('Distance coefficient P'), type=QgsProcessingParameterNumber.Double,
                                                       minValue=0.0, maxValue=99.99, defaultValue=2.0))
        self.addParameter(QgsProcessingParameterNumber(self.COLUMNS,
                                                       self.tr('Number of columns'),
                                                       minValue=0, maxValue=10000000, defaultValue=300))
        self.addParameter(QgsProcessingParameterNumber(self.ROWS,
                                                       self.tr('Number of rows'),
                                                       minValue=0, maxValue=10000000, defaultValue=300))
        self.addParameter(QgsProcessingParameterExtent(self.EXTENT,
                                                       self.tr('Extent'),
                                                       optional=False))
        self.addParameter(QgsProcessingParameterRasterDestination(self.OUTPUT,
                                                                  self.tr('Interpolated')))

    def name(self):
        return 'idwinterpolation'

    def displayName(self):
        return self.tr('IDW interpolation')

    def processAlgorithm(self, parameters, context, feedback):
        interpolationData = ParameterInterpolationData.parseValue(parameters[self.INTERPOLATION_DATA])
        coefficient = self.parameterAsDouble(parameters, self.DISTANCE_COEFFICIENT, context)
        columns = self.parameterAsInt(parameters, self.COLUMNS, context)
        rows = self.parameterAsInt(parameters, self.ROWS, context)
        bbox = self.parameterAsExtent(parameters, self.EXTENT, context)
        output = self.parameterAsOutputLayer(parameters, self.OUTPUT, context)

        if interpolationData is None:
            raise QgsProcessingException(
                self.tr('You need to specify at least one input layer.'))

        layerData = []
        layers = []
        for row in interpolationData.split(';'):
            v = row.split(',')
            data = QgsInterpolator.LayerData()

            # need to keep a reference until interpolation is complete
            layer = QgsProcessingUtils.variantToSource(v[0], context)
            data.source = layer
            layers.append(layer)

            data.valueSource = int(v[1])
            data.interpolationAttribute = int(v[2])
            if v[3] == '0':
                data.sourceType = QgsInterpolator.SourcePoints
            elif v[3] == '1':
                data.sourceType = QgsInterpolator.SourceStructureLines
            else:
                data.sourceType = QgsInterpolator.SourceBreakLines
            layerData.append(data)

        interpolator = QgsIDWInterpolator(layerData)
        interpolator.setDistanceCoefficient(coefficient)

        writer = QgsGridFileWriter(interpolator,
                                   output,
                                   bbox,
                                   columns,
                                   rows)

        writer.writeFile(feedback)
        return {self.OUTPUT: output}