@turf/collect

What is @turf/collect?

@turf/collect is a module from the Turf.js library that allows you to collect properties from one set of features (points) and aggregate them into another set of features (polygons). This is particularly useful for spatial analysis tasks where you need to summarize or aggregate data based on spatial relationships.

What are @turf/collect's main functionalities?

Collect properties from points into polygons

This feature allows you to collect properties from a set of point features and aggregate them into polygon features. In this example, the population property from the points is collected into the polygons.

const turf = require('@turf/turf');

const points = turf.featureCollection([
  turf.point([0, 0], {population: 200}),
  turf.point([2, 2], {population: 300}),
  turf.point([2, 0], {population: 150})
]);

const polygons = turf.featureCollection([
  turf.polygon([[
    [0, 0], [2, 0], [2, 2], [0, 2], [0, 0]
  ]], {name: 'polygon1'})
]);

const collected = turf.collect(polygons, points, 'population', 'collectedPopulations');
console.log(JSON.stringify(collected, null, 2));

Other packages similar to @turf/collect

geostats

The geostats package provides a range of statistical functions for geospatial data, including classification and aggregation. While it does not directly offer the same point-to-polygon aggregation as @turf/collect, it can be used for similar statistical analysis tasks on geospatial data.

jsts

The jsts (JavaScript Topology Suite) package offers a wide range of spatial analysis and geometry operations. It includes functionalities for spatial relationships and operations, but it is more complex and lower-level compared to the specific point-to-polygon aggregation provided by @turf/collect.

README

@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.

Parameters

• polygons FeatureCollection<Polygon> polygons with values on which to aggregate
• points FeatureCollection<Point> points to be aggregated
• inProperty string property to be nested from
• outProperty string property to be nested into

Examples

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<Polygon> polygons with properties listed based on outField

---

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.

Installation

Install this module individually:

$ npm install @turf/collect

Or install the Turf module that includes it as a function:

$ npm install @turf/turf

Changelog

6.2.0

After a bit of hiatus, TurfJS is resuming releases.

⭐️ Major Updates

• ES Modules available for all packages
• Tree shaking should significantly reduce import size of @turf/turf
• Better support for ESM modules (PR https://github.com/Turfjs/turf/pull/1942 - Author @diachedelic)
• Clean-up of test and benchmark running to make publishing easier
• Enforce styling using Prettier
• Enable ESLint and get rid of unused variables
• Upgrade rollup for more correct javascript module builds
• Only include ES5 code

🚀 New Modules

[@turf/boolean-touches][boolean-touches]

Determines if two features touch but do not intersect

[@turf/boolean-valid][boolean-valid]

Checks if the geometry is a valid according to the OGC Simple Feature Specification

[@turf/quadrat-analysis][quadrat-analysis]

Performs a quadrat analysis on a set of points

[@turf/rectangle-grid][rectangle-grid]

Creates a grid of rectangles from a bounding box

[@turf/voroni][voronoi]

Typescript types for the options parameter have been fixed (PR https://github.com/Turfjs/turf/pull/1424 - Author @stevage)

[@turf/points-within-polygon][points-within-polygon]

Typescript types around the Feature's Properties will now be preserved. (PR https://github.com/Turfjs/turf/pull/1761 - Author @rugheid)

[@turf/rewind][rewind]

Typescript types for the 'reverse' option are now correct. Previously it was misnamed as 'reversed'. (PR https://github.com/Turfjs/turf/pull/1786 - Author @jonnycornwell)

[@turf/difference][difference]

No longer publishes an .mjs file.

[@turf/meta][meta]

No longer publishes an .mjs file.

[@turf/tag][tag]

Add MultiPolygon support. (PR https://github.com/Turfjs/turf/pull/1996 - Author bryceroney)

🐛 Bug Fixes

• @turf/centroid Don't visit first point twice when calculating centroid (PR https://github.com/Turfjs/turf/pull/1894 - Author @rowanwins)

• @turf/transform-translate Better handling of negative distances (PR https://github.com/Turfjs/turf/pull/1895 - Author @rowanwins)

• @turf/union, @turf/difference, @turf/intersect Use polygon-clipping library to fix correctness issues (PR https://github.com/Turfjs/turf/pull/1916 - Authors @mbullington, @ngottlieb)

• @turf/buffer Change default number of steps to 8, and actually support the steps option (PR https://github.com/Turfjs/turf/pull/1931 - Author stevenchanin)

• @turf/buffer Fix projection issues that produce undersized buffers at non-equatorial latitudes (PR https://github.com/Turfjs/turf/pull/1956 - Author dyakovlev)

• @turf/helpers Add runtime checks to point() method, fixing an API break (PR https://github.com/Turfjs/turf/pull/1964)

🏅 New Features/Enhancements

• @turf/boolean-overlap Better performance for MultiPoint geometries (PR https://github.com/Turfjs/turf/pull/1910 - Author @mfedderly)

• @turf/helpers Add hectares to convertArea (PR https://github.com/Turfjs/turf/pull/1943 - Author @DanielJDufour)

• @turf/great-circle Update Typescript types to support MultiLineString input (PR https://github.com/Turfjs/turf/pull/1928 - Author kronick)

📖 Documentation

• @turf/square-grid Clarify inputs (PR https://github.com/Turfjs/turf/pull/1885 - Author @raphael-leger)

• @turf/greater-circle Clarify properties option example (PR https://github.com/Turfjs/turf/pull/1888 - Author @chris-catignani)

⚠️ Breaking Change

• @turf/line-to-polygon no longer modifies its input unless the mutate option is true (PR https://github.com/Turfjs/turf/pull/1879 - Author @MortenBirk)

• @turf/unkink-polygon remove Number.prototype.modulo override (PR https://github.com/Turfjs/turf/pull/1978)