classBreaks | API Reference | ArcGIS Maps SDK for JavaScript 4.31

Method Overview

Name	Return Type	Summary	Function
	Promise<ClassBreaksResult>	Generates class breaks for an input field (or expression) of a FeatureLayer based on a given classification method and normalization type.	classBreaks

Method Details

classBreaks Method classBreaks(params){Promise<ClassBreaksResult>}

Generates class breaks for an input field (or expression) of a FeatureLayer based on a given classification method and normalization type.

Parameters

Specification

params Object

See the table below for details about parameters that may be passed to this function.

Specification

The layer from which to generate class breaks.

field String

optional

The class breaks will be generated based on values of this field. If a field is provided, the values from the given field from all features will be queried in the service.

normalizationField String

optional

The field by which to normalize the values returned from the given field.

classificationMethod String

optional

The method for classifying the data. See the table below for a list of possible values.

Possible Value	Description
natural-breaks	Data values that cluster are placed into a single class. Class breaks occur where gaps exist between clusters. You should use this method if your data is unevenly distributed; that is, many features have the same or similar values and there are gaps between groups of values.
equal-interval	Each class has an equal range of values; in other words, the difference between the high and low value is equal for each class. You should use this method if your data is evenly distributed and you want to emphasize the difference in values between the features.
quantile	Each class has roughly the same number of features. If your data is evenly distributed and you want to emphasize the difference in relative position between features, you should use the quantile classification method. If, for example, the point values are divided into five classes, points in the highest class would fall into the top fifth of all points.
standard-deviation	Class breaks are placed above and below the mean value at intervals of `1`, `0.5`, or `0.25` standard deviations until all the data values are included in a class.

Possible Values:"equal-interval"|"natural-breaks"|"quantile"|"standard-deviation"

standardDeviationInterval Number

optional

When classificationMethod = "standard-deviation", this sets the interval at which each class break should be set (e.g. 0.25, 0.33, 0.5, 1). See the table below for a list of possible values.

Possible Value	Description
field	Divides the data value using the attribute value of the field specified in the normalizationField property. A `normalizationField` must be provided if This value is used.
log	Computes the base 10 logarithm of the data value. This can be a useful approach for some data distributions because it reduces the influence of very large data values.
percent-of-total	Divides the data value by the sum of all data values then multiplies by 100. Use normalizationTotal to define the total value by which to normalize.
then set the total amount with which to normalize field values.

minValue Number

optional

The minimum bounding value for the class breaks definition. Use this in conjunction with maxValue to generate class breaks between lower and upper bounds.

maxValue Number

optional

The maximum bounding value for the class breaks definition. Use this in conjunction with minValue to generate class breaks between lower and upper bounds.

numClasses Number

optional

Indicates the number of classes to generate for the class breaks definition.

valueExpression String

optional

An Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions may reference field values using the $feature profile variable and must return a number. This property overrides the field property and therefore is used instead of an input field value.

sqlExpression String

optional

A SQL expression evaluating to a number.

sqlWhere String

optional

A SQL where clause used to filter features for the statistics query. For example, this is useful in situations where you want to avoid dividing by zero as is the case with creating a predominance visualization.

view View

optional

A SceneView or MapView instance is required when a valueExpression is specified.

filter FeatureFilter

optional

A feature filter used to filter statistic queries by geometry. This parameter is only used for filtering statistics by geometry. Any attribute filters set on the FeatureFilter.where property are ignored. Currently, only the intersects spatial relationship is supported. This is useful if you already define a feature filter by geometry on your layer and want to calculate statistics for the included features. Since version 4.25.

features Graphic []

Deprecated since version 4.23. Use useFeaturesInView instead.

optional

A subset of features for which to generate the class breaks.

useFeaturesInView Boolean

optional

Only applicable when the input layer is a service-backed FeatureLayer. When true, statistics will be calculated on the client from features visible in the view. If false, statistics will be requested from the service. Since version 4.23.

forBinning Boolean

optional

Indicates whether the generated statistics are for a binning or clustering visualization. If true, then the input field(s) in this method should refer to aggregate fields defined in the featureReduction property of the layer.

signal AbortSignal

optional

Allows for cancelable requests. If canceled, the promise will be rejected with an error named AbortError. See also AbortController.

Returns

Type	Description
Promise<ClassBreaksResult>	Resolves to an instance of ClassBreaksResult.

Example

classBreaks({
  layer: featureLayer,
  field: "COL_DEG",
  normalizationField: "TOT_POP",
  classificationMethod: "quantile",
  numClasses: 5
}).then(function(response){
  // class break infos that may be passed to the
  // constructor of a ClassBreaksRenderer
  let breakInfos = response.classBreakInfos;
});

Type Definitions

ClassBreak Type Definition ClassBreak

An object describing a single class break generated from the classBreaks() method.

Properties: label String

The label describing the given class break for use in the Legend.

minValue Number

The lower bound of the class break.

maxValue Number

The upper bound of the class break.

ClassBreaksResult Type Definition ClassBreaksResult

Object returned from the classBreaks() method. This object describes classes generated from data in a FeatureLayer for a given field with a specified classification method.

Properties: classBreakInfos ClassBreak []

An array of objects describing the class breaks generated from the classBreaks() method.

minValue Number

The minimum value of features in the dataset. This will be the lower bound of the lowest class break.

maxValue Number

The maximum value of features in the dataset. This will be the upper bound of the highest class break.

normalizationTotal Number

The normalization total if normalizationType is set to percent-of-total when generating class breaks with createClassBreaksRenderer().