[GIS] Spatial Queries in Leaflet, select polygons from (A1,A2…An) which intersect with polygon (B)

esri-leafletjavascriptleafletleaflet-drawturf

I am looking for an online solution for leaflet where I can select and export (console log, geojson, addLayer) a group of polygon from a geojson file which intersect with a drawn polygon (with leaflet draw). Please see the picture:

I tested Esri leaflet but for some reason it is not working form me. I am not sure if it requires an online esri license or I did something wrong (my layer was a geojson not an esri source layer), however I did not get any error messages and also nothing happened. Could anybody confirm this plugin works free without the necessity of any esri related license or data?. If not, my second question is can this question be solved with turf javascript? I know there is turf intersect: var intersection = turf.intersect(poly1, poly2); but this is between 2 polygons and also the end result is new geometry and not a selection of existing ones.

I also find this link which looks useful, but doesn't work for me and I guess the end result would be a new geometries of the intersection:
Intersecting FeatureCollections in turf.js?

Best Answer

if you're not generating from your app, you can create a free developer account and publish a new service from your .geojson and use Esri Leaflet to easily perform a spatial query. you can find more info about the terms of use here

you can also just continue to use turf and loop through each and every feature you want to test and call intersect(). if it returns undefined, the polygons don't intersect.

Related Solutions

[GIS] Simplify GeoJSON by retaining external boundaries (clustering)

A few answers but probably not the ones you're looking for:

Manually digitize the boundaries in desktop GIS
Try leaflet beta, it handles polygon rendering a little better.
Convert the geojson to topojson and/or use the geojson-vt plugin to create vector tiles.

See https://getbounds.com/blog/leaflet-and-geojson-tiles and also the original example found by viewing the source.

Leaflet – Turf Intersect Point with Leaflet GeoJSON Error

Okay, here is a possible solution, I used, 3 layers, muni, county, state, variables, a,b,c, when I would click on the map and it would grab the polygons feature Name from each layer, Then I posted the three feature Names to a dialog. Here is the process to get the values.I also create a marker to see where I clicked.

  map.on('click',function(e){  
        lat = e.latlng.lat;
        lon = e.latlng.lng;
        ProcessClick(lat,lon)   
  });

var theMarker;
var a;
var b;
var c;

function ProcessClick(lat,lon){

    if (theMarker != undefined) {
              map.removeLayer(theMarker);
        };
        if (newgeojsonLayer != undefined) {
              map.removeLayer(newgeojsonLayer);
        };  


    theMarker = L.marker([lat,lon]).addTo(map);  //added to show where you clicked.

        muniLayer.eachLayer(function (layer) {

        //isInside =turf.inside(theMarker.toGeoJSON(), layer.toGeoJSON());

       // Newer method in Turf
       isInside =turf.booleanPointInPolygon((theMarker.toGeoJSON(), layer.toGeoJSON());

        if (isInside){
                a = "City/Town: " + layer.feature.properties.NAME;
                console.log("City/Town: " + layer.feature.properties.NAME);
        }
    });

    countyLayer.eachLayer(function (layer) {

        isInside =turf.inside(theMarker.toGeoJSON(), layer.toGeoJSON());

        if (isInside){
                b = "County: " + layer.feature.properties.NAME;
                console.log("County: " + layer.feature.properties.NAME);
        }
    });

    stateLayer.eachLayer(function (layer) {

        isInside =turf.inside(theMarker.toGeoJSON(), layer.toGeoJSON());

        if (isInside){
            console.log("State: " + layer.feature.properties.STATE_NAME);
            c = "State: " + layer.feature.properties.STATE_NAME;
        }
    })

}

Basically I used it as a popup for all three layers, I just put the values for a,b,c in the popup dialog.

http://www.gistechsolutions.com/leaflet/DEMO/pointsinpoly/index.html http://www.gistechsolutions.com/leaflet/DEMO/pointsinpoly/indextab.html

Related Question

[GIS] Turf intersect doesn’t always work with polygons