@turf/nearest-neighbor-analysis/dist/cjs/index.cjs

Calculates an index based the average distances between points in the dataset, thereby providing inference as to whether the data is clustered, dispersed, or randomly distributed within the study area.

"use strict";Object.defineProperty(exports, "__esModule", {value: true});// index.ts
var _area = require('@turf/area');
var _bbox = require('@turf/bbox');
var _bboxpolygon = require('@turf/bbox-polygon');
var _centroid = require('@turf/centroid');
var _distance = require('@turf/distance');
var _nearestpoint = require('@turf/nearest-point');
var _meta = require('@turf/meta');



var _helpers = require('@turf/helpers');
function nearestNeighborAnalysis(dataset, options) {
  options = options || {};
  const studyArea = options.studyArea || _bboxpolygon.bboxPolygon.call(void 0, _bbox.bbox.call(void 0, dataset));
  const properties = options.properties || {};
  const units = options.units || "kilometers";
  const features = [];
  _meta.featureEach.call(void 0, dataset, (feature) => {
    features.push(_centroid.centroid.call(void 0, feature));
  });
  const n = features.length;
  const observedMeanDistance = features.map((feature, index) => {
    const otherFeatures = _helpers.featureCollection.call(void 0, 
      features.filter((f, i) => {
        return i !== index;
      })
    );
    return _distance.distance.call(void 0, 
      feature,
      _nearestpoint.nearestPoint.call(void 0, feature, otherFeatures).geometry.coordinates,
      { units }
    );
  }).reduce((sum, value) => {
    return sum + value;
  }, 0) / n;
  const populationDensity = n / _helpers.convertArea.call(void 0, _area.area.call(void 0, studyArea), "meters", units);
  const expectedMeanDistance = 1 / (2 * Math.sqrt(populationDensity));
  const variance = 0.26136 / Math.sqrt(n * populationDensity);
  properties.nearestNeighborAnalysis = {
    units,
    arealUnits: units + "\xB2",
    observedMeanDistance,
    expectedMeanDistance,
    nearestNeighborIndex: observedMeanDistance / expectedMeanDistance,
    numberOfPoints: n,
    zScore: (observedMeanDistance - expectedMeanDistance) / variance
  };
  studyArea.properties = properties;
  return studyArea;
}
var index_default = nearestNeighborAnalysis;



exports.default = index_default; exports.nearestNeighborAnalysis = nearestNeighborAnalysis;
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