AggregateField | References | ArcGIS Maps SDK for JavaScript

import AggregateField from "@arcgis/core/layers/support/AggregateField.js";

Inheritance:: AggregateField→Accessor

Since: ArcGIS Maps SDK for JavaScript 4.24

Defines the aggregate fields used in a layer visualized with FeatureReductionBinning or FeatureReductionCluster. An aggregate field aggregates data from a layer's field using a statistic type such as the average or sum.

See also

Example

featureReduction.fields = [{
  name: "SUM_population",
  alias: "Total population",
  onStatisticField: "population",
  statisticType: "sum"
}, {
  name: "AVG_age",
  alias: "Average age",
  onStatisticField: "age",
  statisticType: "avg"
}];

Constructors

Constructor

Parameters

Parameter	Type	Description	Required
properties	`AggregateFieldProperties`

See the properties table for a list of all the properties that may be passed into the constructor.

Properties

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

Property	Type	Class
`alias`	`string \| null \| undefined`
`declaredClass` readonly inherited	`string`	Accessor
`isAutoGenerated`	`boolean`
`name`	`string`
`onStatisticExpression`	`ExpressionInfo`
`onStatisticField`	`string`
`statisticType`	`"avg" \| "avg_angle" \| "sum" \| "mode" \| "count" \| "min" \| "max"`

alias

Property

Type: string | null | undefined

The display name that describes the aggregate field in the Legend, Popup, and other UI elements.

Example

aggregateField.alias = "Total population";

declaredClass

readonlyinherited Property

Type: string

Inherited from: Accessor

The name of the class. The declared class name is formatted as esri.folder.className.

isAutoGenerated

Property

Type: boolean

Since: ArcGIS Maps SDK for JavaScript 4.25

Indicates whether the field was created internally by the JS API's rendering engine for default FeatureReductionCluster visualizations. You should avoid setting or changing this value. If true, then all other properties of the AggregateField are read-only.

Default value: false

name

Property

Type: string

The name of the aggregate field. This should describe the layer's field and aggregation method used. For example, if creating a field that contains the total population for a set of features with a population field, then you could name this field total_population or population_sum.

This field name must start with a letter, and may only contain alphanumeric characters and underscore.

Example

// names the aggregate field that will display the sum of the population
// for all points representing cities in the bin
aggregateField.name = "SUM_population";

onStatisticExpression

autocast Property

Type: ExpressionInfo

Since: ArcGIS Maps SDK for JavaScript 4.25

An object containing an Arcade expression, which evaluates for each child feature represented by the aggregate graphic. All results of the expression will be aggregated using the given statisticType. This expression must follow the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the layer's feature with the $feature profile variable.

Example

// will create an aggregate field for the Population field of the layer.
aggregateField.onStatisticExpression = new ExpressionInfo({
  title: "Population per square kilometer",
  returnType: "number",
  expression: "$feature.population / AreaGeodetic($feature, 'square-kilometers')"
});

onStatisticField

Property

Type: string

Since: ArcGIS Maps SDK for JavaScript 4.25

The name of the layer field to summarize with the given statisticType.

Example

// will create an aggregate field for the Population field of the layer.
aggregateField.onStatisticField = "Population";

statisticType

Property

Type: "avg" | "avg_angle" | "sum" | "mode" | "count" | "min" | "max"

Since: ArcGIS Maps SDK for JavaScript 4.25

Defines the type of statistic used to aggregate data returned from onStatisticField or onStatisticExpression.

Possible Values

Value	Description
`avg`	The average of values in the aggregate. Only available for fields and expressions that return numbers.
`count`	The total number of features in the aggregate. A field does not need to be specified in this case.
`max`	The maximum of all values in the aggregate. Only available for fields and expressions that return numbers.
`min`	The minimum of all values in the aggregate. Only available for fields and expressions that return numbers.
`mode`	The most common or predominant value in the aggregate. Available for fields and expressions that return numbers or strings.
`sum`	The sum of all values in the aggregate. Only available for fields and expressions that return numbers.

Example

// will calculate the sum of the field specified in onStatisticField for all features in the bin.
outStatistic.statisticType = "sum";

Methods

Method	Signature	Class
`fromJSON` inherited static	`fromJSON(json: any): any`	JSONSupportMixin
`clone`	`clone(): AggregateField`
`toJSON` inherited	`toJSON(): any`	JSONSupportMixin

fromJSON

inheritedstatic Method

Signature: fromJSON (json: any): any

Inherited from: JSONSupportMixin

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameters

Parameter	Type	Description	Required
json	`any`	A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns: any
Returns a new instance of this class.

clone

Method

Signature: clone (): AggregateField

Creates a deep clone of the AggregateField object.

Returns: AggregateField
A deep clone of the object that invoked this method.

Example

// Creates a deep clone of the AggregateField object
const sumPopulationField = layer.featureReduction.fields.find( field => field.name === "SUM_population" ).clone();

toJSON

inherited Method

Signature: toJSON (): any

Inherited from: JSONSupportMixin

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns: any
The ArcGIS portal JSON representation of an instance of this class.