@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');

//=tagged

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