topic Re: How to select polygons using a feature set of points? in ArcGIS JavaScript Maps SDK Questions

How to select polygons using a feature set of points?

JaniceBaird — Mon, 13 Jul 2015 20:41:01 GMT

I have a list of id's that I use to select points with matching id's. I then want to use the selected points to select all of the polygons which contain them. I am using a querytask with a where clause to select the points. Now I am not sure how to go about selecting the polygons. Do I need to step through the set of points and use each point geometry individually to select the polygon which contains it?

Any ideas welcome!

Re: How to select polygons using a feature set of points?

ChrisSmith7 — Mon, 13 Jul 2015 20:44:31 GMT

Janice,

I'm not sure if you want to use this yet (it's in Beta in v3.13), but there's a way to process this client-side:

esri/geometry/geometryEngineAsync | API Reference | ArcGIS API for JavaScript

Specifically, contains() would probably help you:

esri/geometry/geometryEngineAsync | API Reference | ArcGIS API for JavaScript

I haven't worked with the client-side geoprocessing yet... I would need to set-up some test apps to see what we can do with it. Perusing the API, though, it seems you would need to step over your points. There's also a way to do this synchronously:

esri/geometry/geometryEngine | API Reference | ArcGIS API for JavaScript

Here's the difference:

A client-side asynchronous geometry engine. The difference between the geometryEngineAsync and geometryEngine modules is the async functions return a Promise that are resolved with the same argument as is returned by the sync functions. See the union method for a code sample.

You could also union your points then run an intersect - that should probably work... Although, now that I think about it, intersect would give you points on the border, too. I'm not sure what the cluster tolerance would be in the API.

Re: How to select polygons using a feature set of points?

thejuskambi — Mon, 13 Jul 2015 20:48:26 GMT

you can use geomertyEngine.union to combine all the points into single geometry and then use that in you queryTask.

check out this post Re: Multiple query tasks

Re: How to select polygons using a feature set of points?

RobertScheitlin__GISP — Mon, 13 Jul 2015 20:55:37 GMT

Janice,

If it is not important to know which point intersects which polygon, then I would create a Multipoint from your point geometries and use that in a single spatial Query by setting the Query object geometry property to that created Multipoint.

Re: How to select polygons using a feature set of points?

JaniceBaird — Mon, 13 Jul 2015 21:52:14 GMT

You all nailed it! I went ahead and used union and used the resulting multipoint to query the polygons. I suppose I could have just created a multipoint from my points as suggested by Robert but was well into my union code before reading his response.

If you are interested, here is the code:

require(["dojo/_base/array","esri/tasks/query","esri/geometry/geometryEngine", "esri/SpatialReference"],

function (array, Query, GeometryEngine, SpatialReference) {

var urlParcelMap = dataLink + "/Assessor/PropertyMap/MapServer/";

var arrayOutFields = ["PNUMBER"];

initQueryTask(urlParcelMap, 4, arrayOutFields);

query.where = "PNUMBER IN (" + searchString + ")";

var pnums = queryTask.execute(query);

pnums.then(function (fset) {

var pts = array.map(fset.features, function (feature) {

return feature.geometry;

});

var union = esriConfig.defaults.geometryService.union(pts);

union.then(function (results) {

arrayOutFields = ["PARCELID"];

initQueryTask(urlParcelMap, 5, arrayOutFields);

query.spatialRelationship = Query.SPATIAL_REL_INTERSECTS;

query.geometry = results;

queryTask.execute(query, showCompQueryResults);

});