Method Overview

Method Details

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:

params Object See the table below for details about parameters that may be passed to this function. Specification: layer FeatureLayer|SceneLayer|CSVLayer|PointCloudLayer 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. 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). 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 that returns a number. This expression can reference field values using the $feature global variable. 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. features Graphic[] optional A subset of features for which to generate the class breaks.

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
  var breakInfos = response.classBreakInfos;
});

Type Definitions

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:

classBreaksInfos Object[] An array of objects describing the class breaks generated from the classBreaks() method. Specification: 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.

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().