Perform a feature analysis

A feature analysis is the process of using the spatial analysis service to perform server-side geometric and analytic operations on feature data. All feature analysis requests are job requests. The easiest way to programmatically run an analysis request to the spatial analysis service is to use ArcGIS REST JS, which provides a Job class that handles long- running operations.

In this tutorial, you use ArcGIS REST JS to perform a hot spot analysis to find statistically significant clusters of parking violations.

Prerequisites

You need the following to access the spatial analysis service and perform feature analysis operations:

An ArcGIS Online account.
A registered application to obtain its Client ID.
The redirect URL of the registered application to use for authentication in the format "https://<server>[:port]" as in: https://localhost:8080.

Steps

Download the starter code

Download the tutorial starter code zip file from ArcGIS Online.

The zip file contains the following:

feature-analysis.html
authenticate.html

The feature-analysis.html file contains basic HTML scaffolding and the OAuth 2.0 code necessary to perform the analysis. The authenticate.html file is the callback page used as part of the authentication process.

Configure authentication

To access the spatial analysis service, you need to have an ArcGIS Online account and sign in with user authentication, which creates a temporary token using OAuth 2.0 protocol. API keys are not supported.

Use the ArcGISIdentityManager class to configure user authentication. To learn more, go to the Authentication chapter.

Go to the developer dashboard > OAuth2.0 tab and copy your application's Client ID.

In the feature-analysis.html file, replace YOUR_CLIENT_ID with your Client ID.

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      let session = null;
      let lastResultUrl = null;

      const clientId = 'YOUR_CLIENT_ID';


      const signInLabel = "Sign in";

      const modalText = "To perform feature analysis you need an ArcGIS Online account. Learn more in <a href='https://developers.arcgis.com/documentation/mapping-apis-and-services/spatial-analysis/feature-analysis/introduction/#limitations'>Limitations.</a>"
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In the authenticate.html file, replace YOUR_CLIENT_ID with your Client ID.

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    <script type="module">
      import { ArcGISIdentityManager } from 'https://cdn.skypack.dev/@esri/arcgis-rest-request@4.0.0';

      const clientId = "YOUR_CLIENT_ID";

      const redirectUri = "authenticate.html";
      ArcGISIdentityManager.completeOAuth2({
        clientId,
        redirectUri
      })
    </script>
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Run the application and navigate to your localhost, for example https://localhost:8080.

You should be able to click the Sign in button and successfully log in to an ArcGIS Online account.

Get the analysis URL

To make a request to the spatial analysis service, you need to get the URL first. The analysis service URL is unique to your organization.

Call the getSelf operation from ArcGIS REST JS to obtain the analysis URL.

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      const getAnalysisUrl = async (withAuth) => {
        const portalSelf = await getSelf({
          authentication: withAuth,
        });

        return portalSelf.helperServices.analysis.url;
      };


      document
        .getElementById('withPopupButton')
        .addEventListener('click', getAuth);
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Make the request

Use the Job class and set the operationURL and params required for the selected analysis.

Create a function that submits a Job request to the spatial analysis service using your organization's analysis URL. Set the params required for a hot spot analysis and authenticate using the session token.

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      const getAnalysisUrl = async (withAuth) => {
        const portalSelf = await getSelf({
          authentication: withAuth,
        });

        return portalSelf.helperServices.analysis.url;
      };

      const runAnalysis = async () => {
        const analysisUrl = await getAnalysisUrl(session);
        const operationUrl = `${analysisUrl}/FindHotSpots/submitJob`;
        const params = {
          analysisLayer: { url: points },
          shapeType: 'Hexagon',
          outputName: {
            serviceProperties: {
              name: `RestJS_find_hot_spots_${new Date().getTime()}`,
            },
          }, //Outputs results as a hosted feature serivce.
        };

        const jobReq = await Job.submitJob({
          url: operationUrl,
          params: params,
          authentication: session,
        });

        // listen to the status event to get updates every time the job status is checked.
        jobReq.on(JOB_STATUSES.Status, (jobInfo) => {
          console.log(jobInfo.status);
        });

        // get all the results, this will start monitoring and trigger events
        const jobResp = await jobReq.getAllResults();

        // jobResp.aggregatedLayer.value.url
        return jobResp;
      };
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Call the runAnalysis function to run the operation.

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        const clearResults = () => {
            document.getElementById('clearResultsBtn').disabled = true;
            document.getElementById('runAnalysisBtn').disabled = false;
            document.getElementById('resultsCBox').checked = false;
        };

      const runAnalysisBtnWasClicked = (evt) => {
        document.getElementById('runAnalysisBtn').hidden = true;
        document.getElementById('progressBar').hidden = false;
        document.getElementById('withPopupButton').disabled = true;

        runAnalysis().then(
          (results) => {
            document.getElementById('runAnalysisBtn').hidden = false;
            document.getElementById('progressBar').hidden = true;
            document.getElementById('withPopupButton').disabled = false;

          },
          (err) => {
            console.log(err);
            document.getElementById('progressBar').hidden = true;
            document.getElementById('runAnalysisBtn').hidden = false;
            document.getElementById('withPopupButton').disabled = false;
            showAlert(err);
          }
        );

      };
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Handle the results

The results of a feature analysis are returned as feature data.

Access the URL of the resulting hosted feature layer.

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        const getResults = () => {
        // You can use this URL to display the results on a map with ArcGIS API for JavaScript or an open source mapping API.
        console.log(lastResultUrl)
        document.getElementById('clearResultsBtn').disabled = false;
        document.getElementById('runAnalysisBtn').disabled = true;
        };

        const clearResults = () => {
            document.getElementById('clearResultsBtn').disabled = true;
            document.getElementById('runAnalysisBtn').disabled = false;
            document.getElementById('resultsCBox').checked = false;
        };

      const runAnalysisBtnWasClicked = (evt) => {
        document.getElementById('runAnalysisBtn').hidden = true;
        document.getElementById('progressBar').hidden = false;
        document.getElementById('withPopupButton').disabled = true;

        runAnalysis().then(
          (results) => {
            document.getElementById('runAnalysisBtn').hidden = false;
            document.getElementById('progressBar').hidden = true;
            document.getElementById('withPopupButton').disabled = false;

            lastResultUrl = results.hotSpotsResultLayer.value.url;
            getResults();

          },
          (err) => {
            console.log(err);
            document.getElementById('progressBar').hidden = true;
            document.getElementById('runAnalysisBtn').hidden = false;
            document.getElementById('withPopupButton').disabled = false;
            showAlert(err);
          }
        );

      };
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Run the app

Run the application and navigate to your localhost, for example: https://localhost:8080.

When you click Run analysis button, you submit a request to the spatial analysis service to perform a hot spot analysis. When the job is complete, you can use the URL of the resulting feature layer in the app. The metadata of the layer will look something like this:

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{
  "currentVersion": 11,
  "id": 0,
  "name": "HotSpotsLayer",
  "type": "Feature Layer",
  "serviceItemId": "898aacb4ea5c4b00b4a51c634f268459",
  "cacheMaxAge": 30,
  "displayField": "",
  "description": "",
  "copyrightText": "",
  "defaultVisibility": true,
  "editingInfo": {
    "lastEditDate": 1667488958822,
    "schemaLastEditDate": 1667488958822,
    "dataLastEditDate": 1667488958822
  },
  "relationships": [],
  "isDataVersioned": false,
  "hasContingentValuesDefinition": false,
  "supportsAppend": true,
  "supportsCalculate": true,
  "supportsASyncCalculate": true,
  "supportsTruncate": true,
  "supportsAttachmentsByUploadId": true,
  "supportsAttachmentsResizing": true,
  "supportsRollbackOnFailureParameter": true,
  "supportsStatistics": true,
  "supportsExceedsLimitStatistics": true,
  "supportsAdvancedQueries": true,
  "supportsValidateSql": true,

See full response

What's next?

To learn how to perform other types of feature analysis, go to the related tutorials in the Mapping APIs and location services guide:

Find and extract data

Find data with attribute and spatial queries using find analysis operations.

Combine data

Overlay, join, and dissolve features using combine analysis operations.

Summarize data

Aggregate and summarize features using summarize analysis operations.

Discover patterns in data

Find patterns and trends in data using spatial analysis operations.