Method Overview

Method Details

histogram(params){Promise<HistogramResult>}

Generates a histogram for data returned from a field in a given layer. The returned object can be used for displaying a histogram to the UI in visualization authoring applications and analytical apps that query and display statistics.

Parameters:

params Object See the table below for details on parameters that may be passed to this function. Specification: layer FeatureLayer|SceneLayer|CSVLayer|PointCloudLayer The layer for which to generate a histogram. field String optional The name of the numeric field for which the histogram will be generated. This property is ignored if a valueExpression is used. 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 histogram. Use this in conjunction with maxValue to generate a histogram between custom lower and upper bounds. maxValue Number optional The maximum bounding value for the histogram. Use this in conjunction with minValue to generate a histogram between custom lower and upper bounds. numBins Number optional Default Value: 10 Indicates the number of classes to generate for the histogram. 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 histogram.

Returns:

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

Example:

histogram({
  layer: featureLayer,
  valueExpression: "( ($feature.POP2020 - $feature.POP2010) / $feature.POP2010 ) * 100"
  view: mapView,
  numBins: 30
}).then(function(histogramResult){
  colorSlider.histogram = histogramResult;
});

Type Definitions

HistogramResult

The result returned from the histogram() method.

Properties:

bins Object[] An array of objects representing each bin in the histogram. Specification: count Number The number of features that are contained between the indicated minValue and maxValue. minValue Number The minimum value of the bin. maxValue Number The maximum value of the bin.

minValue Number The minimum value returned by the field.

maxValue Number The maximum value returned by the field.