FeatureSets can feel a bit unfamiliar if you\u2019re just getting started with Arcade but you don\u2019t need to write long, complicated Arcade expressions just to take advantage of this new functionality.\u00a0 On that note, let\u2019s break down FeatureSets and how they can be used to make better pop-ups. FeatureSets, as the name suggests, are a set of features.\u00a0 How many features will depend on your data and the functions used in the expression.\u00a0 In the simplest case, if you define a FeatureSet from a feature layer, it is all the features in the feature layer.\u00a0 The second aspect of FeatureSets is how you reference or access them.\u00a0 When defining a FeatureSet from a feature layer, you need to tell the Arcade expression where to look.\u00a0 That is done with global variables:<\/p>\n Before we dive into some examples, I suggest you take a quick look at the following web map<\/a> to familiarize yourself with the two layers\u2014Neighborhoods and Street Tree locations\u2014from Toronto\u2019s Open Data Catalogue<\/a>. If you want to follow along, save a copy of the map to your account.<\/p>\n Crack open the Arcade editor for the Neighborhoods layer by configuring the pop-up and adding a new expression, give the expression the name \u201cNumber of Trees\u201d, paste in the following code, and then click Test.<\/p>\n The expression above tells you how many trees are in the neighborhood when you open the pop-up.\u00a0 First it defines a FeatureSet called trees using the name of the layer in the web map ($map).\u00a0 On the next line, we define a variable that stores the number of trees that intersect the polygon ($feature). Arcade allows you to chain functions together for convenience. The last line returns the count value to be used in the pop-up.\u00a0 Properly referencing the layer for a FeatureSet can be tricky to type out by hand.\u00a0 The good news is you don\u2019t have to; you can browse to the layer from the Globals tab and just insert the snippet.<\/p>\n <\/p>\n"},{"acf_fc_layout":"image","image":{"ID":378082,"id":378082,"title":"FeatureSets","filename":"featuresets_map01.gif","filesize":184623,"url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcade\/mapping\/whats-new-with-arcade-taking-a-stroll-through-featuresets-part-1\/featuresets_map01","alt":"","author":"6981","description":"","caption":"","name":"featuresets_map01","status":"inherit","uploaded_to":378032,"date":"2018-12-12 13:08:27","modified":"2018-12-12 13:08:43","menu_order":0,"mime_type":"image\/gif","type":"image","subtype":"gif","icon":"https:\/\/www.esri.com\/arcgis-blog\/wp-includes\/images\/media\/default.png","width":1528,"height":938,"sizes":{"thumbnail":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","thumbnail-width":213,"thumbnail-height":131,"medium":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","medium-width":425,"medium-height":261,"medium_large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","medium_large-width":768,"medium_large-height":471,"large":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","large-width":1528,"large-height":938,"1536x1536":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","1536x1536-width":1528,"1536x1536-height":938,"2048x2048":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","2048x2048-width":1528,"2048x2048-height":938,"card_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","card_image-width":757,"card_image-height":465,"wide_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/12\/featuresets_map01.gif","wide_image-width":1528,"wide_image-height":938}},"image_position":"center","orientation":"horizontal","hyperlink":""},{"acf_fc_layout":"content","content":" You\u2019ll notice in the video above that there are two ways to define a FeatureSet: by Name or by Id.\u00a0 Both are identical in functionality, and how you refer to the layer is up to you.\u00a0 If you expect your layer\u2019s name to change, then I would recommend using the Id instead.<\/p>\n Save the pop-up and click on a Neighborhood on the map, and you\u2019ll see your expression in the pop-up.<\/p>\n With the basics out of the way, let\u2019s take a look at a few other functions that compliment FeatureSets, such as Filter().\u00a0 The Filter function allows you to filter the FeatureSet based on a SQL\u201992 where clause. Maybe within the context of your map you are interested in Maple trees.\u00a0 Starting with the expression above, you can add a new expression (or modify the existing one) to keep only Maple trees.<\/p>\n You can also modify the expression to understand the density of trees in the neighborhood:<\/p>\n Bundle that all up in a nice pop-up and you now have dynamic information coming from another layer.<\/p>\n <\/p>\n"},{"acf_fc_layout":"storymap","title":"","description":"","static":false,"storymap_url":"https:\/\/www.arcgis.com\/apps\/Minimalist\/index.html?appid=9b448fa56ba8461fade10049cd15daee<\/a>"},{"acf_fc_layout":"content","content":" FeatureSets are hot off the press and not supported everywhere yet.\u00a0 If you want to take advantage of FeaturesSets in your maps and apps, you will need to use web apps that are written with the ArcGIS API for Javascript 3.27.\u00a0 Support for FeatureSets will be arriving in the 4.x Javascript API, ArcGIS Pro (2.3), ArcGIS Runtime, and our Native apps in future releases.<\/p>\n As you get more familiar with FeatureSets, you\u2019ll quickly learn how to write more rich and complicated expressions (iteration, multiple layers, and more), as with any dynamic calculation you have to balance performance and user experience.\u00a0 If your data is too large and your expression complex or you have too many expressions, you may find the Arcade expression evaluates too slowly to make for an effective user experience.\u00a0 This can happen because FeatureSets are a connection to a set of features in memory or on a server and all the information must be retrieved first before evaluating the expression(s). If you find yourself in that situation after creating your expression, I highly recommend taking the time to calculate the expression to an existing field in your layer using Calculate Field<\/a> (more on in a future blog article).<\/p>\n Keep an eye on our blog<\/a>\u00a0page for a deeper dive into FeatureSets in the coming weeks.\u00a0 In the meantime, if you want to read more about Arcade, be sure to check out the Developers Site<\/a> along with our Community Github<\/a> site with great Arcade examples. Or checkout Geonet<\/a> for a sneak peak of\u00a0 some things we’ll cover in Part 2<\/a>.<\/p>\n"}],"authors":[{"ID":6981,"user_firstname":"Paul","user_lastname":"Barker","nickname":"Paul Barker","user_nicename":"pbarker_esri","display_name":"Paul Barker","user_email":"PBarker@esri.com","user_url":"http:\/\/www.arcgis.com","user_registered":"2018-03-02 00:19:05","user_description":"Product Engineer for ArcGIS Online and technology enthusiast.","user_avatar":"
\n<\/a><\/p>\nUsing FeatureSets<\/h3>\n
\n
\/\/ get the count for all trees in the Neighborhood
\nvar trees = FeatureSetByName($map,\"Urban Forestry\")
\nvar countTrees = Count(Intersects(trees,$feature))
\nreturn countTrees<\/code><\/p>\nvar mapleTrees = Filter(FeatureSetByName($map, \"Urban Forestry\"),\"COMMON_NAM LIKE '%MAPLE%'\")
\nvar countMapleTrees = Count(Intersects(mapleTrees, $feature))
\nreturn countMapleTrees <\/code><\/p>\nvar trees = FeatureSetByName($map,\"Urban Forestry\")
\nvar countTrees = Count(Intersects(trees,$feature))
\nvar treeDensity = countTrees \/ AreaGeodetic($feature, 'square-kilometers')
\nreturn Round(treeDensity,2)<\/code><\/p>\nThings to consider<\/h3>\n
Learn more<\/h3>\n
