@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

• polygon1 Feature<(Polygon | MultiPolygon)> input Polygon feature
• polygon2 Feature<(Polygon | MultiPolygon)> Polygon feature to difference from polygon1

Examples

var polygon1 = turf.polygon([[
  [128, -26],
  [141, -26],
  [141, -21],
  [128, -21],
  [128, -26]
]], {
  "fill": "#F00",
  "fill-opacity": 0.1
});
var polygon2 = turf.polygon([[
  [126, -28],
  [140, -28],
  [140, -20],
  [126, -20],
  [126, -28]
]], {
  "fill": "#00F",
  "fill-opacity": 0.1
});

var difference = turf.difference(polygon1, polygon2);

//addToMap
var addToMap = [polygon1, polygon2, difference];

Returns (Feature<(Polygon | MultiPolygon)> | null) a Polygon or MultiPolygon feature showing the area of polygon1 excluding the area of polygon2 (if empty returns null)

---

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/turf

Changelog

6.4.0

🏅 New Features/Enhancements

• @turf/boolean-point-on-line Added an epislon option to help in floating point comparison. (PR https://github.com/Turfjs/turf/pull/2051 - Author @okcoker)

🐛 Bug Fixes

• @turf/line-slice-along Fixed a bug where the offset distance equal to the length of the line (PR https://github.com/Turfjs/turf/pull/2030 - Author @EricPKerr)

• @turf/helpers Fixed the conversion ratio for converting meters to yards and vice-versa (PR https://github.com/Turfjs/turf/pull/2046 - Author @anotherhale)

• @turf/center-median Fixed a missing TS type import (PR https://github.com/Turfjs/turf/pull/2044 - Author @Seairth)

• `@turf/bezier-spline Fix a bug ensuring the spline result reaches the end of the input (PR https://github.com/Turfjs/turf/pull/2090 - Author @the-nemz)

📖 Documentation

• @turf/transform-rotate and @turf/ellipse) Improve documentation for angle parameter (PR https://github.com/Turfjs/turf/pull/2016 - Author @pasieronen)

• @turf/line-chunk Fix an invalid anchor (PR https://github.com/Turfjs/turf/pull/2071 - Author @GraxMonzo)

• @turf/distance Enhance distance doco so supported inputs are clearer (PR https://github.com/Turfjs/turf/pull/2032 - Author @rowanwins)

🔔 Misc

• @turf/concave Replace deprecated topojson dependency (PR https://github.com/Turfjs/turf/pull/2037 - Author @elliots)

• Work towards enabling TS Strict Mode (PR https://github.com/Turfjs/turf/pull/2053 - Author @mfedderly)