@turf/dissolve

What is @turf/dissolve?

@turf/dissolve is a module in the Turf.js library that allows you to merge adjacent or overlapping polygons into a single polygon. This is particularly useful in geographic information systems (GIS) for simplifying complex polygonal data.

What are @turf/dissolve's main functionalities?

Dissolve Polygons

This feature allows you to merge multiple polygons into a single polygon. The code sample demonstrates how to create a collection of polygons and then dissolve them into one polygon using the @turf/dissolve module.

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

const polygons = turf.featureCollection([
  turf.polygon([[
    [-70.603637, -33.399918],
    [-70.614624, -33.395332],
    [-70.639343, -33.392466],
    [-70.659942, -33.394759],
    [-70.683975, -33.404504],
    [-70.697021, -33.419406],
    [-70.701141, -33.434306],
    [-70.700454, -33.446339],
    [-70.694274, -33.458369],
    [-70.682601, -33.465816],
    [-70.668869, -33.472117],
    [-70.646209, -33.473835],
    [-70.624923, -33.472117],
    [-70.609817, -33.468107],
    [-70.595397, -33.458369],
    [-70.587158, -33.442901],
    [-70.587158, -33.426283],
    [-70.590591, -33.414248],
    [-70.594711, -33.406224],
    [-70.603637, -33.399918]
  ]]),
  turf.polygon([[
    [-70.604705, -33.396344],
    [-70.629425, -33.392466],
    [-70.641098, -33.396344],
    [-70.652771, -33.401084],
    [-70.661697, -33.410803],
    [-70.666504, -33.421617],
    [-70.666504, -33.432428],
    [-70.661697, -33.443237],
    [-70.652771, -33.453045],
    [-70.641098, -33.457784],
    [-70.629425, -33.457784],
    [-70.617752, -33.453045],
    [-70.607452, -33.443237],
    [-70.604705, -33.432428],
    [-70.604705, -33.421617],
    [-70.604705, -33.410803],
    [-70.604705, -33.396344]
  ]])
]);

const dissolved = turf.dissolve(polygons);
console.log(JSON.stringify(dissolved));

Other packages similar to @turf/dissolve

jsts

JSTS (JavaScript Topology Suite) is a JavaScript library for processing and analyzing planar geometric objects. It provides similar functionalities to @turf/dissolve, such as union, intersection, and difference operations on polygons. However, JSTS is a more comprehensive library for geometric operations and may have a steeper learning curve.

martinez-polygon-clipping

Martinez Polygon Clipping is a library for performing boolean operations on polygons, such as union, intersection, and difference. It is highly efficient and can handle complex polygonal data. While it provides similar functionalities to @turf/dissolve, it is more focused on boolean operations rather than general GIS tasks.

README

@turf/dissolve

dissolve

Dissolves a FeatureCollection of polygons based on a property. Note that multipart features within the collection are not supported

Parameters

• featureCollection FeatureCollection<Polygon> input feature collection to be dissolved
• propertyName [string] property name on which to dissolve features

Examples

var features = turf.featureCollection([
  turf.polygon([[[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]]], {"combine": "yes"}),
  turf.polygon([[[0, -1], [0, 0], [1, 0], [1, -1], [0,-1]]], {"combine": "yes"}),
  turf.polygon([[[1,-1],[1, 0], [2, 0], [2, -1], [1, -1]]], {"combine": "no"}),
]);

var dissolved = turf.dissolve(features, 'combine');

//addToMap
var addToMap = [features, dissolved]

Returns FeatureCollection<Polygon> a FeatureCollection containing the dissolved polygons

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/dissolve

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

$ npm install @turf/turf