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