Find closest facility to an incident (interactive)

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Find a route to the closest facility from a location.

screenshot

Use case

Quickly and accurately determining the most efficient route between a location and a facility is a frequently encountered task. For example, a paramedic may need to know which hospital in the vicinity offers the possibility of getting an ambulance patient critical medical care in the shortest amount of time. Solving for the closest hospital to the ambulance's location using an impedance of "travel time" would provide this information.

How to use the sample

Click near any of the hospitals and a route will be displayed from that clicked location to the nearest hospital.

How it works

  1. Create a ClosestFacilityTask using an Url from an online service.
  2. Get a ClosestFacilityParameters from this task, using createDefaultParameters.
  3. Add a list of facilities to the task parameters, using ClosestFacilityParameters::setFacilities(const QList<Facility>& facilities);.
  4. Add an incident to the parameters, using ClosestFacilityParameters::setIncidents(const QList<Incident>& incidents);.
  5. Get the ClosestFacilityResult from solving the task with parameters: , ClosestFacilityTask::solveClosestFacility(const ClosestFacilityParameters& closestFacilityParameters);.
  6. Get the ranked list of the indices of the closest facilities to the incident, ClosestFacilityResult::rankedFacilities(int incidentIndex) const;.
  7. Get the index of the closest facility (e.g. the first index in the ranked list).
  8. Find the closest facility route, ClosestFacilityResult::route(int facilityIndex, int incidentIndex) const;.
  9. Display the route on the MapView:
  • create a Graphic from the route geometry, new Graphic(route.routeGeometry(), this).
  • add graphic to GraphicsOverlay which is attached to the mapview.

Relevant API

  • ClosestFacilityParameters
  • ClosestFacilityResult
  • ClosestFacilityRoute
  • ClosestFacilityTask
  • Facility
  • Graphic
  • GraphicsOverlay
  • Incident
  • MapView

Tags

incident, network analysis, route, search

Sample Code

ClosestFacility.cppClosestFacility.cppClosestFacility.hClosestFacility.qml
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// [WriteFile Name=FindClosestFacilityToAnIncidentInteractive, Category=Routing]
// [Legal]
// Copyright 2017 Esri.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "ClosestFacility.h"

#include "ClosestFacilityParameters.h"
#include "ClosestFacilityTask.h"
#include "Facility.h"
#include "Map.h"
#include "MapQuickView.h"
#include "PictureMarkerSymbol.h"
#include "SimpleMarkerSymbol.h"
#include "SimpleRenderer.h"

using namespace Esri::ArcGISRuntime;

const QUrl ClosestFacility::facilityImageUrl(
    QStringLiteral("https://static.arcgis.com/images/Symbols/SafetyHealth/Hospital.png"));

const QUrl ClosestFacility::sanDiegoRegion(
    QStringLiteral("https://sampleserver6.arcgisonline.com/arcgis/rest/services/NetworkAnalysis/SanDiego/NAServer/ClosestFacility"));

ClosestFacility::ClosestFacility(QQuickItem* parent /* = nullptr */):
  QQuickItem(parent),
  m_task(new ClosestFacilityTask(sanDiegoRegion, this))
{
}

ClosestFacility::~ClosestFacility() = default;

void ClosestFacility::init()
{
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<ClosestFacility>("Esri.Samples", 1, 0, "ClosestFacilitySample");
}


void ClosestFacility::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML MapView component
  m_mapView = findChild<MapQuickView*>("mapView");
  m_mapView->setWrapAroundMode(WrapAroundMode::Disabled);

  // Create a map using the streets basemap
  m_map = new Map(BasemapStyle::ArcGISStreets, this);

  // set view to be over San Diego
  m_map->setInitialViewpoint(Viewpoint(Point(-13041154, 3858170, SpatialReference(3857)), 1e5));

  // Set map to map view
  m_mapView->setMap(m_map);

  createFacilities();
  createGraphics();

  connect(m_task, &ClosestFacilityTask::doneLoading, this, [this] (Error loadError)
  {
    if (!loadError.isEmpty())
      return;

    if (m_task->loadStatus() != LoadStatus::Loaded)
      return;

    setupRouting();
  });

  m_task->load();
}

bool ClosestFacility::busy() const
{
  return m_busy;
}

QString ClosestFacility::message() const
{
  return m_message;
}

void ClosestFacility::setBusy(bool val)
{
  if (m_busy == val)
    return;

  m_message.clear();
  m_busy = val;
  emit busyChanged();
  emit messageChanged();
}

void ClosestFacility::createFacilities()
{
  // List of facilities to be placed around San Diego area
  m_facilities.append(Facility(Point(-1.3042129900625112E7, 3860127.9479775648, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3042193400557665E7, 3862448.873041752, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3046882875518233E7, 3862704.9896770366, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3040539754780494E7, 3862924.5938606677, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3042571225655518E7, 3858981.773018156, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3039784633928463E7, 3856692.5980474586, SpatialReference::webMercator())));
  m_facilities.append(Facility(Point(-1.3049023883956768E7, 3861993.789732541, SpatialReference::webMercator())));
}

void ClosestFacility::createGraphics()
{
  // create a symbol for the graphics
  PictureMarkerSymbol* facilitySymbol = new PictureMarkerSymbol(facilityImageUrl, this);
  facilitySymbol->setHeight(30);
  facilitySymbol->setWidth(30);

  // create a graphics overlay for the facilities and add a renderer for the symbol
  m_facilityOverlay = new GraphicsOverlay(this);
  SimpleRenderer* facilityRenderer = new SimpleRenderer(facilitySymbol, this);
  m_facilityOverlay->setRenderer(facilityRenderer);

  // add a graphic at the location of each of the facilities
  for (const Facility& facility : qAsConst(m_facilities))
  {
    Graphic* facilityGraphic = new Graphic(facility.geometry(), this);
    m_facilityOverlay->graphics()->append(facilityGraphic);
  }

  // add the overlay to the map view
  m_mapView->graphicsOverlays()->append(m_facilityOverlay);

  // create a symbol for the route graphic
  float lineWidth = 2.0f;
  SimpleLineSymbol* routeSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, Qt::blue, lineWidth, this);

  // create a graphics overlay for the routes and add a renderer for the symbol
  m_resultsOverlay = new GraphicsOverlay(this);
  SimpleRenderer* routeRenderer = new SimpleRenderer(routeSymbol, this);
  m_resultsOverlay->setRenderer(routeRenderer);

  // add the overlay to the map view
  m_mapView->graphicsOverlays()->append(m_resultsOverlay);

  // add a graphic to the route overlay
  m_routeGraphic = new Graphic(this);
  m_resultsOverlay->graphics()->append(m_routeGraphic);

  // create a symbol for the incident graphics
  SimpleMarkerSymbol* incidentSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Cross, Qt::black, 20, this);

  // create a graphics overlay for the incidents and add a renderer for the symbol
  m_incidentsOverlay = new GraphicsOverlay(this);
  SimpleRenderer* incidentRenderer = new SimpleRenderer(incidentSymbol, this);
  m_incidentsOverlay->setRenderer(incidentRenderer);

  // add the overlay to the map view
  m_mapView->graphicsOverlays()->append(m_incidentsOverlay);

  // add a graphic to the incident overlay
  m_incidentGraphic = new Graphic(this);
  m_incidentsOverlay->graphics()->append(m_incidentGraphic);
}

void ClosestFacility::setupRouting()
{
  connect(m_task, &ClosestFacilityTask::createDefaultParametersCompleted, this, [this](
          QUuid, Esri::ArcGISRuntime::ClosestFacilityParameters defaultParameters)
  {
    setBusy(false);

    m_facilityParams = defaultParameters;
    m_facilityParams.setFacilities(m_facilities);
  });

  connect(m_task, &ClosestFacilityTask::solveClosestFacilityCompleted, this, [this]
          (QUuid, ClosestFacilityResult closestFacilityResult)
  {
    setBusy(false);

    if (closestFacilityResult.isEmpty())
    {
      m_message = "Incident not within San Diego Area!";
      emit messageChanged();
    }

    QList<int> rankedList = closestFacilityResult.rankedFacilityIndexes(0);
    int closestFacilityIdx = rankedList.first();

    int incidentIndex = 0; // 0 since there is just 1 incident at a time
    ClosestFacilityRoute route = closestFacilityResult.route(closestFacilityIdx, incidentIndex);

    m_routeGraphic->setGeometry(route.routeGeometry());
  });

  connect(m_mapView, &MapQuickView::mouseClicked, this, [this](QMouseEvent& mouseEvent)
  {
    if (busy())
      return;

    Point mapPoint = m_mapView->screenToLocation(mouseEvent.x(), mouseEvent.y());
    Point incidentPoint(mapPoint.x(), mapPoint.y(), SpatialReference::webMercator());

    m_incidentGraphic->setGeometry(incidentPoint);

    solveRoute(incidentPoint);
  });

  setBusy(true);
  m_task->createDefaultParameters();
}

void ClosestFacility::solveRoute(const Esri::ArcGISRuntime::Point& incidentPoint)
{
  m_facilityParams.clearIncidents();
  m_facilityParams.setIncidents(QList<Incident> {Incident(incidentPoint)});

  setBusy(true);
  // find the closest facility to the incident
  m_task->solveClosestFacility(m_facilityParams);
}

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