FeatureReductionCluster

Defines the symbol size of the largest cluster in points (or pixels if specified). Adjusting clusterMaxSize generally should be considered if the clusterRadius is modified.

For example, if you prefer cluster icons to not overlap, then the clusterMaxSize should be substantially smaller than the clusterRadius.

If a custom renderer is defined for cluster, and that renderer contains a SizeVariable, then this property is ignored and cluster sizes are determined using the renderer's size variable.

Defines the symbol size of the smallest cluster in points (or pixels if specified). If labeling clusters with a count or some other information in the center of the cluster, then having a clusterMinSize larger than the default is generally preferred.

Keep in mind that this size may be smaller than the symbol size of individual non-clustered features in the layer. In that scenario, you should either reduce the size of the symbol(s) in the layer's renderer or increase the clusterMinSize to be larger than the size of individual point symbols to avoid confusion for the end user. This is most likely to happen when cluster size represents feature count.

If a custom renderer is defined for cluster, and that renderer contains a SizeVariable, then this property is ignored and cluster sizes are determined using the renderer's size variable.

Defines the radius in points (or pixels if specified) of the area in which multiple features will be grouped and visualized as a single cluster. Adjusting clusterRadius generally should be considered if the clusterMaxSize is modified.

For example, if you prefer cluster graphics to not overlap, then the clusterRadius should be substantially larger than the clusterMaxSize.

An array of aggregate fields that summarize layer fields from features contained within each cluster. These fields may be used by the popupTemplate, labelingInfo, and renderer.

Some fields are internally automatically created by the JS API's rendering engine for use in default cluster renderers (not set by the developer). The AggregateField.isAutoGenerated property indicates whether a field was internally created by the JS API. All auto-generated fields are read-only. They are discarded and replaced with new fields each time the user changes the underlying layer's renderer. Therefore, auto-generated fields should always be used with caution.

The table below describes the general rules for how the rendering engine names auto-generated aggregate fields.

Defines labels for clusters as an array of LabelClass. When set, labels independent of the layer.labelingInfo are used to convey information about the clusters, including the count of all features in the cluster, the average, or predominant values of fields mapped by the renderer.

Label expressions may only refer to aggregate fields defined in the fields property. Auto-generated fields may be used, but are at risk of being discarded if the underlying layer's renderer changes. See fields for more information.

It is advisable to turn off label deconfliction when labeling clusters with a count in the center of the cluster. To generate suggested labels for your cluster configuration based on the layer's renderer, see clusterLabelCreator.

Multiple Label classes with different where clauses can be used to define several labels with varying styles on the same feature. Likewise, multiple label classes may be used to label different types of clusters (e.g. blue labels for small clusters and red labels for large ones).

Indicates whether to display labels for the clusters. If true, labels will appear as defined in the labelingInfo property.

Defines the maximum view scale at which clustering is enabled. If the user zooms in beyond the scale specified here, clustering will be disabled and only individual features will be displayed in the view. Once the user zooms out past this scale, clustering will be re-enabled. A value of 0 means clustering is always enabled, and therefore clusters may be visible at any view scale.

Indicates whether to display the cluster popup. If true, popups will open when the user clicks or taps a cluster. If false, the popup as defined in the popupTemplate will be persisted, but won't be displayed on click/tap.

The PopupTemplate to apply to clustered graphics. When set, a popupTemplate independent of the layer.popupTemplate is used. This popup can display summary information for the cluster, including the count of all features in the cluster and the average or predominant values of fields mapped by the renderer.

To generate a suggested predefined popup template for your cluster configuration based on the layer's renderer, see clusterPopupTemplateCreator.

The PopupTemplate may contain one or more Arcade expressions following the specification defined by the Arcade Feature Reduction Popup Profile. Expressions must return a string or a number and may access data values from the cluster and its aggregated features with the $feature and $aggregatedFeatures profile variables.

Popup expressions may only refer to aggregate fields defined in the fields property. Auto-generated fields may be used, but are at risk of being discarded if the underlying layer's renderer changes. See fields for more information about this behavior.

The following popupTemplate configurations will display the popups shown in the images below.

Cluster count

layer.featureReduction = {
  type: "cluster",
  popupTemplate: {
    content: "This cluster represents {cluster_count} earthquakes."
  }
};

Clusters by predominant type

The following featureReduction configuration assumes the layer's renderer is a UniqueValueRenderer who's field is named religion.

layer.featureReduction = {
  type: "cluster",
  popupTemplate: {
    content: [{
      type: "text",
      text: "This cluster represents <b>{cluster_count}</b> features."
    }, {
      type: "text",
      text: "The predominant place of worship in this cluster is <b>{cluster_type_religion}</b>."
    }]
  }
};

Clusters with visual variables

The following featureReduction configuration assumes the layer's renderer contains visual variables referencing fields named WIND_SPEED, WIND_DIRECT, TEMP.

layer.featureReduction = {
  type: "cluster",
  popupTemplate: {
    content: [{
      type: "text",
      text: "This cluster represents <b>{cluster_count}</b> weather stations."
    }, {
      type: "fields",
      fieldInfos: [{
        fieldName: "cluster_avg_WIND_SPEED",
        label: "Average wind speed (km/h)",
        format: {
          places: 0
        }
      }, {
        fieldName: "cluster_avg_WIND_DIRECT",
        label: "Average wind direction (degrees)",
          format: {
            places: 0
          }
      }, {
          fieldName: "cluster_avg_TEMP",
          label: "Average temperature (°F)",
          format: {
           places: 0
          }
       }]
    }]
  }
};

The renderer used to override the default style of the clusters. All fields used by this renderer must be AggregateFields defined in the fields property of this class.

For points, the default cluster style is inferred by the underlying layer's renderer. Each cluster will be styled with a symbol summarizing the points included in the cluster based on the underlying layer's renderer configuration. See Styles and configurations for more information about this behavior. In this scenario, the renderer will be persisted when the layer is saved to the web map, but it will be flagged as "auto generated" in the isAutoGenerated property of the the renderer.authoringInfo object. All auto generated renderers are discarded and replaced each time the underlying layer's renderer is changed.

This property allows you to override the auto generated cluster styling using any renderer type suitable for point geometries. For example, if you want to render clusters as pie charts, you can define a PieChartRenderer in this property. Custom renderers set on this property are not discarded when the underlying layer's renderer changes. Setting this property to null will cause clusters to render using the auto-generated renderer based on the layer's renderer.

Defining a renderer here will override the symbols of all aggregate and individual features in the view. If you want to define a dedicated cluster symbol, but retain the layer's renderer for individual features, then use the symbol property (for point layers only).

For polyline and polygon layers, you must define a renderer with marker symbols (or pie charts) to display clusters as there is no auto generated cluster renderer for these geometry types.

A symbol used to override the default cluster style. Unlike the renderer property, this symbol doesn't affect individual features (i.e. clusters of size 1). Use this property to create a dedicated cluster symbol while retaining the symbology of individual features.

The feature reduction type.