@turf/difference

What is @turf/difference?

@turf/difference is a module in the Turf.js library that allows you to compute the geometric difference between two polygons. This is useful in geospatial analysis for determining the area that is unique to one polygon when compared to another.

What are @turf/difference's main functionalities?

Compute Difference Between Two Polygons

This feature allows you to compute the difference between two polygons. The resulting polygon represents the area that is unique to the first polygon when compared to the second polygon.

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

const polygon1 = turf.polygon([[
  [-82.574787, 35.594087],
  [-82.574787, 35.615581],
  [-82.545261, 35.615581],
  [-82.545261, 35.594087],
  [-82.574787, 35.594087]
]]);

const polygon2 = turf.polygon([[
  [-82.560024, 35.585153],
  [-82.560024, 35.602602],
  [-82.52964, 35.602602],
  [-82.52964, 35.585153],
  [-82.560024, 35.585153]
]]);

const difference = turf.difference(polygon1, polygon2);
console.log(difference);

Other packages similar to @turf/difference

jsts

JSTS is a JavaScript library of spatial predicates and functions for processing geometry. It is a port of the Java Topology Suite (JTS). JSTS provides a more comprehensive set of geometric operations compared to @turf/difference, including union, intersection, and buffer operations.

martinez-polygon-clipping

Martinez Polygon Clipping is a library for performing boolean operations on polygons, such as union, intersection, and difference. It is known for its performance and accuracy, making it a good alternative to @turf/difference for complex polygon operations.

README

turf-difference

difference

Finds the difference between two polygons by clipping the second polygon from the first.

Parameters

• poly1 Feature<Polygon> input Polygon feaure
• poly2 Feature<Polygon> Polygon feature to difference from poly1

Examples

var poly1 = {
  "type": "Feature",
  "properties": {
    "fill": "#0f0"
  },
  "geometry": {
    "type": "Polygon",
    "coordinates": [[
      [-46.738586, -23.596711],
      [-46.738586, -23.458207],
      [-46.560058, -23.458207],
      [-46.560058, -23.596711],
      [-46.738586, -23.596711]
    ]]
  }
};
var poly2 = {
  "type": "Feature",
  "properties": {
    "fill": "#00f"
  },
  "geometry": {
    "type": "Polygon",
    "coordinates": [[
      [-46.650009, -23.631314],
      [-46.650009, -23.5237],
      [-46.509246, -23.5237],
      [-46.509246, -23.631314],
      [-46.650009, -23.631314]
    ]]
  }
};

var differenced = turf.difference(poly1, poly2);
differenced.properties.fill = '#f00';

var polygons = {
  "type": "FeatureCollection",
  "features": [poly1, poly2]
};

//=polygons

//=differenced

Returns Feature<Polygon> a Polygon feature showing the area of poly1 excluding the area of poly2

---

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-difference

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

$ npm install turf