@turf/collect

collect

Merges a specified property from a FeatureCollection of points into a
FeatureCollection of polygons. Given an inProperty on points and an outProperty
for polygons, this finds every point that lies within each polygon, collects the
inProperty values from those points, and adds them as an array to outProperty
on the polygon.

$3

* polygons [FeatureCollection][1]<[Polygon][2]> polygons with values on which to aggregate
* points [FeatureCollection][1]<[Point][3]> points to be aggregated
* inProperty [string][4] property to be nested from
* outProperty [string][4] property to be nested into

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``javascript
var poly1 = turf.polygon([[[0,0],[10,0],[10,10],[0,10],[0,0]]]);
var poly2 = turf.polygon([[[10,0],[20,10],[20,20],[20,0],[10,0]]]);
var polyFC = turf.featureCollection([poly1, poly2]);
var pt1 = turf.point([5,5], {population: 200});
var pt2 = turf.point([1,3], {population: 600});
var pt3 = turf.point([14,2], {population: 100});
var pt4 = turf.point([13,1], {population: 200});
var pt5 = turf.point([19,7], {population: 300});
var pointFC = turf.featureCollection([pt1, pt2, pt3, pt4, pt5]);
var collected = turf.collect(polyFC, pointFC, 'population', 'values');
var values = collected.features[0].properties.values
//=values => [200, 600]

//addToMap
var addToMap = [pointFC, collected]
`

Returns [FeatureCollection][1]<[Polygon][2]> polygons with properties listed based on outField

[1]: https://tools.ietf.org/html/rfc7946#section-3.3

[2]: https://tools.ietf.org/html/rfc7946#section-3.1.6

[3]: https://tools.ietf.org/html/rfc7946#section-3.1.2

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

---

This module is part of the Turfjs project, an open source module collection dedicated to geographic algorithms. It is maintained in the Turfjs/turf repository, where you can create PRs and issues.

$3

Install this single module individually:

`sh
$ npm install @turf/collect
`

Or install the all-encompassing @turf/turf module that includes all modules as functions:

`sh
$ npm install @turf/turf
``