standardDeviationalEllipse
Description
Takes a collection of features and returns a standard deviational ellipse, also known as a “directional distribution.” The standard deviational ellipse aims to show the direction and the distribution of a dataset by drawing an ellipse that contains about one standard deviation’s worth (~ 70%) of the data.
This module mirrors the functionality of Directional Distribution in ArcGIS and the QGIS Standard Deviational Ellipse Plugin
Bibliography
• Robert S. Yuill, “The Standard Deviational Ellipse; An Updated Tool for Spatial Description,” Geografiska Annaler 53, no. 1 (1971): 28–39, doi:{@link [https://doi.org/10.2307/490885 | 10.2307/490885}](https://doi.org/10.2307/490885 | 10.2307/490885}).
• Paul Hanly Furfey, “A Note on Lefever’s “Standard Deviational Ellipse,” American Journal of Sociology 33, no. 1 (1927): 94—98, doi:{@link [https://doi.org/10.1086/214336 | 10.1086/214336}](https://doi.org/10.1086/214336 | 10.1086/214336}).
Parameters
| Name | Type | Description |
|---|---|---|
| points | FeatureCollection<Point> | GeoJSON points |
| options? | Object | Optional parameters (default {}) |
| options.weight? | string | the property name used to weight the center |
| options.steps? | number | number of steps for the polygon (default 64) |
| options.properties? | Object | properties to pass to the resulting ellipse (default {}) |
Returns
Feature<Polygon> an elliptical Polygon that includes approximately 1 SD of the dataset within it.
Examples
const bbox = [-74, 40.72, -73.98, 40.74];
const points = turf.randomPoint(400, { bbox: bbox });
const sdEllipse = turf.standardDeviationalEllipse(points);
Installation
$ npm install @turf/standard-deviational-ellipse
import { standardDeviationalEllipse } from "@turf/standard-deviational-ellipse";
const result = standardDeviationalEllipse(...);
$ npm install @turf/turf
import * as turf from "@turf/turf";
const result = turf.standardDeviationalEllipse(...);