turf-deviation

turf deviation module

turf.deviation(polygons, points, inField, outField)

Calculates the standard deviation value of a field for a set of Point|points within a set of Polygon|polygons.

Parameters

parameter	type	description
polygons	FeatureCollection.<Polygon>	input polygons
points	FeatureCollection.<Point>	input points
inField	String	the field in points from which to aggregate
outField	String	the field to append to polygons representing deviation

Example

var polygons = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [[
          [-97.807159, 30.270335],
          [-97.807159, 30.369913],
          [-97.612838, 30.369913],
          [-97.612838, 30.270335],
          [-97.807159, 30.270335]
        ]]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [[
          [-97.825698, 30.175405],
          [-97.825698, 30.264404],
          [-97.630691, 30.264404],
          [-97.630691, 30.175405],
          [-97.825698, 30.175405]
        ]]
      }
    }
  ]
};
var points = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "population": 500
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-97.709655, 30.311245]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 400
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-97.766647, 30.345028]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 600
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-97.765274, 30.294646]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 500
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-97.753601, 30.216355]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 200
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-97.667083, 30.208047]
      }
    }
  ]
};

var inField = "population";
var outField = "pop_deviation";

var deviated = turf.deviation(
  polygons, points, inField, outField);

var resultFeatures = points.features.concat(
  deviated.features);
var result = {
  "type": "FeatureCollection",
  "features": resultFeatures
};

//=result

Returns FeatureCollection.<Polygon>, polygons with appended field representing deviation

Installation

Requires nodejs.

$ npm install turf-deviation

Tests

$ npm test