@turf/tag

What is @turf/tag?

@turf/tag is a module within the Turf.js library that allows you to tag points with properties from polygons. This is particularly useful for geospatial analysis where you need to associate point data with the regions they fall into.

What are @turf/tag's main functionalities?

Tagging Points with Polygon Properties

This feature allows you to tag points with properties from polygons they fall into. In this example, points are tagged with the 'name' property from the polygons.

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

const points = turf.points([
  [-77, 44],
  [-77, 38],
  [-77, 39]
]);

const polygons = turf.featureCollection([
  turf.polygon([[[-80, 41], [-70, 41], [-70, 39], [-80, 39], [-80, 41]]], { name: 'polygon1' }),
  turf.polygon([[[-80, 45], [-70, 45], [-70, 43], [-80, 43], [-80, 45]]], { name: 'polygon2' })
]);

const taggedPoints = turf.tag(points, polygons, 'name', 'polygonName');
console.log(taggedPoints);

Other packages similar to @turf/tag

geolib

Geolib is a library for geospatial calculations. It provides functions for distance calculations, finding points within a radius, and more. Unlike @turf/tag, it does not specifically focus on tagging points with polygon properties but offers a broader range of geospatial utilities.

leaflet

Leaflet is a popular open-source JavaScript library for mobile-friendly interactive maps. While it provides extensive functionalities for map visualization and interaction, it does not offer built-in support for tagging points with polygon properties like @turf/tag.

jsts

JSTS is a JavaScript library of spatial predicates and functions for processing geometry. It is more focused on geometric operations and spatial analysis, providing a different set of functionalities compared to @turf/tag.

README

@turf/tag

tag

Takes a set of points and a set of polygons and performs a spatial join.

Parameters

• points FeatureCollection<Point> input points
• polygons FeatureCollection<Polygon> input polygons
• field string property in polygons to add to joined {} features
• outField string property in points in which to store joined property from polygons

Examples

var pt1 = turf.point([-77, 44]);
var pt2 = turf.point([-77, 38]);
var poly1 = turf.polygon([[
  [-81, 41],
  [-81, 47],
  [-72, 47],
  [-72, 41],
  [-81, 41]
]], {pop: 3000});
var poly2 = turf.polygon([[
  [-81, 35],
  [-81, 41],
  [-72, 41],
  [-72, 35],
  [-81, 35]
]], {pop: 1000});

var points = turf.featureCollection([pt1, pt2]);
var polygons = turf.featureCollection([poly1, poly2]);

var tagged = turf.tag(points, polygons, 'pop', 'population');

//addToMap
var addToMap = [tagged, polygons]

Returns FeatureCollection<Point> points with containingPolyId property containing values from polyId

---

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/tag

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)