Display clusters

Display a web map with a point feature layer that has feature reduction enabled to aggregate points into clusters.

Use case

Feature clustering can be used to dynamically aggregate groups of points that are within proximity of each other in order to represent each group with a single symbol. Such grouping allows you to see patterns in the data that are difficult to visualize when a layer contains hundreds or thousands of points that overlap and cover each other.

How to use the sample

Pan and zoom the map to view how clustering is dynamically updated. Toggle clustering off to view the original point features that make up the clustered elements. When clustering is toggled on, you can tap on a clustered geoelement to view aggregated information and summary statistics for that cluster as well as a list of containing geoelements. When clustering is disabled and you tap on the original feature you get access to information about individual power plant features.

How it works

1. Create a map from a web map PortalItem.
2. Get the cluster enabled layer from the map’s operational layers.
3. Get the FeatureReduction from the feature layer and set isEnabled to enable or disable clustering on the feature layer.
4. Use the onSingleTapGesture modifier to listen for tap events on the map view.
5. Identify tapped features on the map using identify(on:screenPoint:tolerance:returnPopupsOnly:maximumResults:) on the feature layer and pass in the map screen point location.
6. Get the Popup from the resulting IdentifyLayerResult and use it to construct a PopupView.
7. Get the AggregateGeoElement from the IdentifyLayerResult and use geoElements to retrieve the contained GeoElement objects.
8. Use a FloatingPanel to display the popup information from the PopupView and the list containing the GeoElement objects.

Relevant API

• AggregateGeoElement
• FeatureLayer
• FeatureReduction
• GeoElement
• IdentifyLayerResult

About the data

This sample uses a web map that displays the Esri Global Power Plants feature layer with feature reduction enabled. When enabled, the cluster’s symbology shows the color of the most common power plant type, and a size relative to the average plant capacity of the cluster.

Additional information

Graphics in a graphics overlay can also be aggregated into clusters. To do this, set the featureReduction property on the GraphicsOverlay to a new ClusteringFeatureReduction.

Tags

aggregate, bin, cluster, group, merge, normalize, reduce, summarize