Data expression - list of merged polygons that intersect with another polygon layer (two FeatureSets)

KerryKang

Hello, 

 

I hope to get some direction on how I can get the list of merged polygons (A+B) that intersect another polygon layer (C).

 

I have two polygon layer A. Municipalities and B. Regional Districts. I merged A and B into a new FeatureSet in Data Expression using common attributes such as admin type and name of the area.

 

Then, I want to count how many of these admin areas are affected by a weather event (polygon C), ideally returning all the names & geometry, not just count of intersects so that I can use the returned FeatureSet for further like filters.

 

-- This is what I did so far. The third  variable (fs3) is the one need to be used to define intersect, and has not been used yet.

 

====================================

// Portal

var p = Portal('https://xyz.maps.arcgis.com');

// Create FeatureSet for points - municipality

var fs1 = FeatureSetByPortalItem(p,'xyz', 0, ['*'], true);

// Create Featureset for lines - regional district

var fs2 = FeatureSetByPortalItem(p,'yyy', 13 ,['*'], true);

 

var fs3  = Filter(FeatureSetByPortalItem(Portal('https://arcgis.com/'), 'zzz',1,['*'], true),"ImpactLevel=5");

 

// Create empty feature array and feat object for output

var features = [];

var feat;

// Iterate fs1

for (var feature in fs1) {

   

    // Create feature with aggregated values

    feat = {

        'attributes': {    

            'admin_type': ['Municipality'],

            'name':feature['Admin_area_name']

        }

    };

   

    // Push feature into array

    Push(features, feat);

};

for (var feature in fs2) {

 

   

    // Create feature with aggregated values

    feat = {

        'attributes': {

            'admin_type': ['Regional District'],

            'name':feature['admin_area_name']

        }

    };

   

    // Push feature into array

    Push(features, feat);

};

// Create dict for merged output FeatureSet

var out_dict = {

    'fields': [

       

        {'name': 'admin_type', 'type': 'esriFieldTypeString'},

        {'name': 'name', 'type': 'esriFieldTypeString'}

       

    ],

  'geometryType': '',

  'features': features

};

// Convert dictionary to feature set - mergend A and B

//return FeatureSet(Text(out_dict));

 

//Intersect the new FeatureSet with fs3 (polygon C)

JohannesLindner

To post formatted code:

 

• In your loops over fs1 and fs2, you use feature as iteration variable. This overwrites the native Arcade function Feature. That's not a problem here, but in general, it's not recommended to do that, because you can't use those native functions anymore.
• You try to input arrays into the admin_type field. 'admin_type': ['Municipality'] should be 'admin_type': 'Municipality'
• You say you want to output the geometry, but you don't set it in your output fs nor in your out features.
  • Upon further inspection, you seem to have points (municipalities), lines (districts) and polygons (weather events). You can't combine these in the same featureset.

 

You can get  the features intersecting a target feature with Intersects(). You would need a third loop over your merged features that intersects those features with the weather events.

But actually, it should be faster to do it the other way around: 

• loop over the weather events
  • intersects with fs1 and copy each intersected feature
  • do the same for fs2

Something like this:

var municipalities = 
var districts = 
var weather_events = 

out_fs = {
    fields: [
        {name: "admin_type", type: "esriFieldTypeString"},
        {name: "name", type: "esriFieldTypeString"},
    ],
    geometryType: "",
    features: []
}

for(var weather_event in weather_events) {
    var i_municipalities = Intersects(weather_event, municipalities)
    for(var m in i_municipalities) {
        var f = {attributes: {admin_type: "Municipality", name: m.Municipality}}
        Push(out_fc.features, f)
    }
    var i_districts = Intersects(weather_event, districts)
    for(var d in i_districts) {
        var f = {attributes: {admin_type: "Regional District", name: d.admin_area_name}}
        Push(out_fc.features, f)
    }
}
return Featureset(out_fs)