Find service area

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Find the service area within a network from a given point.

Image of find service area

Use case

A service area shows locations that can be reached from a facility based off a certain impedance, such as travel time or distance. Barriers can increase impedance by either adding to the time it takes to pass through the barrier or by altogether preventing passage.

You might calculate the region around a hospital in which ambulances can service in 30 min or less.

How to use the sample

In order to find any service areas at least one facility needs to be added to the map view.

  • To add a facility, tap the facility button, then tap anywhere on the map.
  • To add a barrier, tap the barrier button, and tap multiple locations on map. Hit the barrier button again to finish drawing barrier. Hitting any other button will also stop the barrier from drawing.
  • To show service areas around facilities that were added, tap show service areas button.
  • The reset button clears all graphics and resets the service area task.

How it works

  1. Create a new ServiceAreaTask from a network service.
  2. Create default ServiceAreaParameters from the service area task.
  3. Set the parameters to return polygons (true) to return all service areas.
  4. Add a ServiceAreaFacility to the parameters.
  5. Get the ServiceAreaResult by solving the service area task using the parameters.
  6. Get any ServiceAreaPolygons that were returned.
  7. Display the service area polygons as graphics in a GraphicsOverlay on the MapView.

Relevant API

  • PolylineBarrier
  • ServiceAreaFacility
  • ServiceAreaParameters
  • ServiceAreaPolygon
  • ServiceAreaResult
  • ServiceAreaTask

Tags

Routing and Logistics, barriers, facilities, impedance

Sample Code

FindServiceArea.cs
                                                                                                                                                                                                                                                                                                                                                              
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// Copyright 2018 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.

using Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks.NetworkAnalysis;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace ArcGISRuntime.Samples.FindServiceArea
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Find service area",
        category: "Network analysis",
        description: "Find the service area within a network from a given point.",
        instructions: "In order to find any service areas at least one facility needs to be added to the map view.",
        tags: new[] { "Routing and Logistics", "barriers", "facilities", "impedance" })]
    public class FindServiceArea : Activity
    {
        // Hold a reference to the map view.
        private MapView _myMapView;

        // Uri for the service area around San Diego.
        private Uri _serviceAreaUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/NetworkAnalysis/SanDiego/NAServer/ServiceArea");

        // Create buttons for the UI.
        private Button _facilityButton;
        private Button _barrierButton;
        private Button _serviceAreasButton;
        private Button _resetButton;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Find service area (interactive)";

            CreateLayout();
            Initialize();
        }

        private void CreateLayout()
        {
            // Create a new layout for the entire page.
            LinearLayout layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Add layouts for the buttons.
            LinearLayout topRow = new LinearLayout(this) { Orientation = Orientation.Horizontal };
            LinearLayout bottomRow = new LinearLayout(this) { Orientation = Orientation.Horizontal };

            // Make a layout parameter for the buttons.
            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MatchParent,
                ViewGroup.LayoutParams.MatchParent,
                1.0f
            );

            // Create a button to reset the route display, add it to the toolbar.
            _facilityButton = new Button(this) { Text = "Place Facility", LayoutParameters = param };
            _facilityButton.Click += PlaceFacilityButtonClick;
            topRow.AddView(_facilityButton);

            // Create a button to reset the route display, add it to the toolbar.
            _barrierButton = new Button(this) { Text = "Draw Barrier", LayoutParameters = param };
            //_barrierButton.SetWidth(toolbar.Width);
            _barrierButton.Click += DrawBarrierButtonClick;
            topRow.AddView(_barrierButton);

            // Create a button to reset the route display, add it to the toolbar.
            _serviceAreasButton = new Button(this) { Text = "Show Service Areas", LayoutParameters = param };
            _serviceAreasButton.Click += ShowServiceAreasButtonClick;
            bottomRow.AddView(_serviceAreasButton);

            // Create a button to reset the route display, add it to the toolbar.
            _resetButton = new Button(this) { Text = "Reset", LayoutParameters = param };
            _resetButton.Click += ResetClick;
            bottomRow.AddView(_resetButton);

            // Add rows of buttons to the layout.
            layout.AddView(topRow);
            layout.AddView(bottomRow);

            // Add the map view to the layout.
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

            // Show the layout in the app.
            SetContentView(layout);
        }

        private void Initialize()
        {
            // Center the map on San Diego.
            Map streetsMap = new Map(BasemapStyle.ArcGISLightGray)
            {
                InitialViewpoint = new Viewpoint(32.73, -117.14, 30000)
            };
            _myMapView.Map = streetsMap;

            // Create graphics overlays for all of the elements of the map.
            _myMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Add a new behavior for double taps on the MapView.
            _myMapView.GeoViewDoubleTapped += (s, e) =>
            {
                // If the sketch editor complete command is enabled, a sketch is in progress.
                if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
                {
                    // Set the event as handled.
                    e.Handled = true;

                    // Finish any drawing.
                    _myMapView.SketchEditor.CompleteCommand.Execute(null);

                    // Update UI.
                    _barrierButton.Text = "Draw barrier";
                }
            };
        }

        private async void PlaceFacilityButtonClick(object sender, EventArgs e)
        {
            // Disable the button so the user recognizes that they are placing a facility.
            _facilityButton.Enabled = false;

            try
            {
                // Let the user tap on the map view using the point sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Point;
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbology for a facility.
                PictureMarkerSymbol facilitySymbol = new PictureMarkerSymbol(new Uri("https://static.arcgis.com/images/Symbols/SafetyHealth/Hospital.png"))
                {
                    Height = 30,
                    Width = 30
                };

                // Create a graphic for the facility.
                Graphic facilityGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Facility" } }, facilitySymbol)
                {
                    ZIndex = 2
                };

                // Add the graphic to the graphics overlay.
                _myMapView.GraphicsOverlays[0].Graphics.Add(facilityGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                CreateErrorDialog("Error drawing facility:\n" + ex.Message);
            }

            // Enable the button when the user is done.
            _facilityButton.Enabled = true;
        }

        private async void DrawBarrierButtonClick(object sender, EventArgs e)
        {
            // Finish any drawings in progress.
            if (_barrierButton.Text != "Draw barrier")
            {
                // Finish the sketch.
                if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
                {
                    _myMapView.SketchEditor.CompleteCommand.Execute(null);
                }

                // Update the UI.
                _barrierButton.Text = "Draw barrier";

                return;
            }

            try
            {
                // Update the UI.
                _barrierButton.Text = "Finish drawing";

                // Let the user draw on the map view using the polyline sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Polyline;
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbol for the barriers.
                SimpleLineSymbol barrierSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Black, 5.0f);

                // Create the graphic to be used for barriers.
                Graphic barrierGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Barrier" } }, barrierSymbol)
                {
                    ZIndex = 1
                };

                // Add a graphic from the polyline the user drew.
                _myMapView.GraphicsOverlays[0].Graphics.Add(barrierGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                CreateErrorDialog("Error drawing barrier:\n" + ex.Message);
            }

            // Enable the button when the user is done.
            _barrierButton.Enabled = true;
        }

        private async void ShowServiceAreasButtonClick(object sender, EventArgs e)
        {
            // Finish any drawings in progress.
            if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.CompleteCommand.Execute(null);
            }

            // Update the UI.
            _barrierButton.Text = "Draw barrier";

            // Use a local variable for the graphics overlay.
            GraphicCollection allGraphics = _myMapView.GraphicsOverlays[0].Graphics;

            // Get a list of the facilities from the graphics overlay.
            List<ServiceAreaFacility> serviceAreaFacilities = (from g in allGraphics
                                                               where (string)g.Attributes["Type"] == "Facility"
                                                               select new ServiceAreaFacility((MapPoint)g.Geometry)).ToList();

            // Check that there is at least 1 facility to find a service area for.
            if (!serviceAreaFacilities.Any())
            {
                CreateErrorDialog("Must have at least one Facility!");
                return;
            }

            // Create the service area task and parameters based on the Uri.
            ServiceAreaTask serviceAreaTask = await ServiceAreaTask.CreateAsync(_serviceAreaUri);

            // Store the default parameters for the service area in an object.
            ServiceAreaParameters serviceAreaParameters = await serviceAreaTask.CreateDefaultParametersAsync();

            // Add impedance cutoffs for facilities (drive time minutes).
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(2.0);
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(5.0);

            // Set the level of detail for the polygons.
            serviceAreaParameters.PolygonDetail = ServiceAreaPolygonDetail.High;

            // Get a list of the barriers from the graphics overlay.
            List<PolylineBarrier> polylineBarriers = (from g in allGraphics
                                                      where (string)g.Attributes["Type"] == "Barrier"
                                                      select new PolylineBarrier((Polyline)g.Geometry)).ToList();

            // Add the barriers to the service area parameters.
            serviceAreaParameters.SetPolylineBarriers(polylineBarriers);

            // Update the parameters to include all of the placed facilities.
            serviceAreaParameters.SetFacilities(serviceAreaFacilities);

            // Clear existing graphics for service areas.
            foreach (Graphic g in allGraphics.ToList())
            {
                // Check if the graphic g is a service area.
                if ((string)g.Attributes["Type"] == "ServiceArea")
                {
                    allGraphics.Remove(g);
                }
            }

            try
            {
                // Solve for the service area of the facilities.
                ServiceAreaResult result = await serviceAreaTask.SolveServiceAreaAsync(serviceAreaParameters);

                // Loop over each facility.
                for (int i = 0; i < serviceAreaFacilities.Count; i++)
                {
                    // Create list of polygons from a service facility.
                    List<ServiceAreaPolygon> polygons = result.GetResultPolygons(i).ToList();

                    // Symbol for the outline of the service areas.
                    SimpleLineSymbol serviceOutline = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.DarkGray, 3.0f);

                    // Create a list of fill symbols for the polygons.
                    List<SimpleFillSymbol> fillSymbols = new List<SimpleFillSymbol>();
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 0, 0), serviceOutline));
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 165, 0), serviceOutline));

                    // Loop over every polygon in every facilities result.
                    for (int j = 0; j < polygons.Count; j++)
                    {
                        // Create the graphic for the service areas, alternating between fill symbols.
                        Graphic serviceGraphic = new Graphic(polygons[j].Geometry, new Dictionary<string, object>() { { "Type", "ServiceArea" } }, fillSymbols[j % 2])
                        {
                            ZIndex = 0
                        };

                        // Add graphic for service area. Alternate the color of each polygon.
                        allGraphics.Add(serviceGraphic);
                    }
                }
            }
            catch (Esri.ArcGISRuntime.Http.ArcGISWebException exception)
            {
                if (exception.Message.ToString().Equals("Unable to complete operation."))
                {
                    CreateErrorDialog("Facility not within San Diego area!");
                }
                else
                {
                    CreateErrorDialog("An ArcGIS web exception occurred. \n" + exception.Message);
                }
            }
        }

        private void ResetClick(object sender, EventArgs e)
        {
            // Clear all of the graphics.
            _myMapView.GraphicsOverlays[0].Graphics.Clear();
        }

        private void CreateErrorDialog(string message)
        {
            // Create a dialog to show message to user.
            AlertDialog alert = new AlertDialog.Builder(this).Create();
            alert.SetMessage(message);
            alert.Show();
        }
    }
}

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