turf-average

turf average module

turf.average(polygons, points, field, outputField)

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

Parameters

parameter	type	description
polygons	FeatureCollection.<Polygon>	polygons with values on which to average
points	FeatureCollection.<Point>	points from which to calculate the average
field	String	the field in the points features from which to pull values to average
outputField	String	the field in polygons to put results of the averages

Example

var polygons = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [[
          [10.666351, 59.890659],
          [10.666351, 59.936784],
          [10.762481, 59.936784],
          [10.762481, 59.890659],
          [10.666351, 59.890659]
        ]]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [[
          [10.764541, 59.889281],
          [10.764541, 59.937128],
          [10.866165, 59.937128],
          [10.866165, 59.889281],
          [10.764541, 59.889281]
        ]]
      }
    }
  ]
};
var points = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "population": 200
      },
      "geometry": {
        "type": "Point",
        "coordinates": [10.724029, 59.926807]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 600
      },
      "geometry": {
        "type": "Point",
        "coordinates": [10.715789, 59.904778]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 100
      },
      "geometry": {
        "type": "Point",
        "coordinates": [10.746002, 59.908566]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 200
      },
      "geometry": {
        "type": "Point",
        "coordinates": [10.806427, 59.908910]
      }
    }, {
      "type": "Feature",
      "properties": {
        "population": 300
      },
      "geometry": {
        "type": "Point",
        "coordinates": [10.79544, 59.931624]
      }
    }
  ]
};

var averaged = turf.average(
 polygons, points, 'population', 'pop_avg');

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

//=result

Returns FeatureCollection.<Polygon>, polygons with the value of outField set to the calculated averages

Installation

Requires nodejs.

$ npm install turf-average

Tests

$ npm test