gogeos

README

gogeos - Go library for spatial data operations and geometric algorithms

gogeos is a library for Go that provides operations on spatial data and geometric algorithms.

It provides bindings to the GEOS C library.

Quick start

package main

import (
	"fmt"

	"github.com/paulsmith/gogeos/geos"
)

func main() {
	line, _ := geos.FromWKT("LINESTRING (0 0, 10 10, 20 20)")
	buf, _ := line.Buffer(2.5)
	fmt.Println(buf)
	// Output: POLYGON ((18.2322330470336311 21.7677669529663689, 18.61…
}

Overview

Functionality

• Binary predicates - intersects, disjoint, etc.
• Topology operations - difference, union, etc.
• Polygonization, line merging, and simplification
• Prepared geometries (for better performance for common binary predicates)
• Validity checking
• DE-9IM
• Geometry info - area, length, distance, etc.
• IO - WKT & WKB read/write

gogeos is an open source project.

Community

• Source code: GitHub project
• Issues tracker
• Mailing list: gogeos@googlegroups.com
• IRC: #gogeos on freenode

Installation

Requirements

• GEOS 3.3.8 or 3.3.9

GEOS must be installed on your system to build gogeos.

Ubuntu

$ apt-get install libgeos-dev

OS X - homebrew

$ brew install geos

From source (all OSes)

$ wget http://download.osgeo.org/geos/geos-3.3.8.tar.bz2
$ tar xvfj geos-3.3.8.tar.bz2
$ cd geos-3.3.8
$ ./configure
$ make
$ sudo make install

Installing gogeos

$ go get github.com/paulsmith/gogeos/geos

Documentation

• Main gogeos documentation
• godoc

Example

Let’s say you have two polygons, A (blue) and B (orange).

One of the most common things to do with a spatial data library like gogeos is compute the intersection of two or more geometries. Intersection is just a method on geometry objects in gogeos, which takes one argument, the other geometry, and computes the intersection with the receiver. The result is a new geometry, C (magenta):

C := geos.Must(A.Intersection(B))

geos.Must is just a convenience function that takes the output of any gogeos function or method that returns a geometry and an error. It panics if the error is non-null, otherwise returning the geometry, making it more convenient to use in single-value contexts. In production code, though, you’ll want to check the error value.

(NB: these graphics weren't produced by gogeos directly - I used the excellent draw2d package to render the output of gogeos functions.)

License

MIT. See COPYING.

Copyright (c) 2013 Paul Smith