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

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

"""
***************************************************************************
    HubDistancePoints.py
    ---------------------
    Date                 : May 2010
    Copyright            : (C) 2010 by Michael Minn
    Email                : pyqgis at michaelminn 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.                                   *
*                                                                         *
***************************************************************************
"""
from builtins import next

__author__ = 'Michael Minn'
__date__ = 'May 2010'
__copyright__ = '(C) 2010, Michael Minn'

# 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,
                       QgsGeometry,
                       QgsFeatureSink,
                       QgsDistanceArea,
                       QgsFeature,
                       QgsFeatureRequest,
                       QgsWkbTypes,
                       QgsApplication,
                       QgsProject,
                       QgsProcessingUtils)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterTableField
from processing.core.parameters import ParameterSelection
from processing.core.outputs import OutputVector

from processing.tools import dataobjects

from math import sqrt


class HubDistancePoints(QgisAlgorithm):
    POINTS = 'POINTS'
    HUBS = 'HUBS'
    FIELD = 'FIELD'
    UNIT = 'UNIT'
    OUTPUT = 'OUTPUT'

    UNITS = ['Meters',
             'Feet',
             'Miles',
             'Kilometers',
             'Layer units'
             ]

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

    def __init__(self):
        super().__init__()
        self.units = [self.tr('Meters'),
                      self.tr('Feet'),
                      self.tr('Miles'),
                      self.tr('Kilometers'),
                      self.tr('Layer units')]

        self.addParameter(ParameterVector(self.POINTS,
                                          self.tr('Source points layer')))
        self.addParameter(ParameterVector(self.HUBS,
                                          self.tr('Destination hubs layer')))
        self.addParameter(ParameterTableField(self.FIELD,
                                              self.tr('Hub layer name attribute'), self.HUBS))
        self.addParameter(ParameterSelection(self.UNIT,
                                             self.tr('Measurement unit'), self.units))

        self.addOutput(OutputVector(self.OUTPUT, self.tr('Hub distance'), datatype=[dataobjects.TYPE_VECTOR_POINT]))

    def name(self):
        return 'distancetonearesthubpoints'

    def displayName(self):
        return self.tr('Distance to nearest hub (points)')

    def processAlgorithm(self, parameters, context, feedback):
        layerPoints = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.POINTS), context)
        layerHubs = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.HUBS), context)
        fieldName = self.getParameterValue(self.FIELD)

        units = self.UNITS[self.getParameterValue(self.UNIT)]

        if layerPoints.source() == layerHubs.source():
            raise GeoAlgorithmExecutionException(
                self.tr('Same layer given for both hubs and spokes'))

        fields = layerPoints.fields()
        fields.append(QgsField('HubName', QVariant.String))
        fields.append(QgsField('HubDist', QVariant.Double))

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fields, QgsWkbTypes.Point, layerPoints.crs(),
                                                                     context)

        index = QgsProcessingUtils.createSpatialIndex(layerHubs, context)

        distance = QgsDistanceArea()
        distance.setSourceCrs(layerPoints.crs())
        distance.setEllipsoid(QgsProject.instance().ellipsoid())

        # Scan source points, find nearest hub, and write to output file
        features = QgsProcessingUtils.getFeatures(layerPoints, context)
        total = 100.0 / layerPoints.featureCount() if layerPoints.featureCount() else 0
        for current, f in enumerate(features):
            src = f.geometry().boundingBox().center()

            neighbors = index.nearestNeighbor(src, 1)
            ft = next(layerHubs.getFeatures(QgsFeatureRequest().setFilterFid(neighbors[0]).setSubsetOfAttributes([fieldName], layerHubs.fields())))
            closest = ft.geometry().boundingBox().center()
            hubDist = distance.measureLine(src, closest)

            attributes = f.attributes()
            attributes.append(ft[fieldName])
            if units == 'Feet':
                attributes.append(hubDist * 3.2808399)
            elif units == 'Miles':
                attributes.append(hubDist * 0.000621371192)
            elif units == 'Kilometers':
                attributes.append(hubDist / 1000.0)
            elif units != 'Meters':
                attributes.append(sqrt(
                    pow(src.x() - closest.x(), 2.0) +
                    pow(src.y() - closest.y(), 2.0)))
            else:
                attributes.append(hubDist)

            feat = QgsFeature()
            feat.setAttributes(attributes)

            feat.setGeometry(QgsGeometry.fromPoint(src))

            writer.addFeature(feat, QgsFeatureSink.FastInsert)
            feedback.setProgress(int(current * total))

        del writer