GoToNewWorld / osm

General purpose library for reading, writing and working with OpenStreetMap data

osm

This package is a general purpose library for reading, writing and working with OpenStreetMap data in Go (golang). It has the ability to read OSM XML and PBF data formats available at planet.osm.org or via the v0.6 API.

Made available by the package are the following types:

• Node
• Way
• Relation
• Changeset
• Note
• User

And the following “container” types:

• OSM - container returned via API
• Change - used by the replication API
• Diff - corresponds to Overpass Augmented diffs

List of sub-package utilities

• annotate - adds lon/lat, version, changeset and orientation data to way and relation members
• osmapi - supports all the v0.6 read/data endpoints
• osmgeojson - OSM to GeoJSON conversion compatible with osmtogeojson
• osmpbf - stream processing of *.osm.pbf files
• osmxml - stream processing of *.osm xml files
• replication - fetch replication state and change files

Concepts

This package refers to the core OSM data types as Objects. The Node, Way, Relation, Changeset, Note and User types implement the osm.Object interface and can be referenced using the osm.ObjectID type. As a result it is possible to have a slice of []osm.Object that contains nodes, changesets and users.

Individual versions of the core OSM Map Data types are referred to as Elements and the set of versions for a give Node, Way or Relation is referred to as a Feature. For example, an osm.ElementID could refer to "Node with id 10 and version 3" and the osm.FeatureID would refer to "all versions of node with id 10." Put another way, features represent a road and how it's changed over time and an element is a specific version of that feature.

A number of helper methods are provided for dealing with features and elements. The idea is to make it easy to work with a Way and its member nodes, for example.

Scanning large data files

For small data it is possible to use the encoding/xml package in the Go standard library to marshal/unmarshal the data. This is typically done using the osm.OSM or osm.Change "container" structs.

For large data the package defines the Scanner interface implemented in both the osmxml and osmpbf sub-packages.

type osm.Scanner interface {
	Scan() bool
	Object() osm.Object
	Err() error
	Close() error
}

This interface is designed to mimic the bufio.Scanner interface found in the Go standard library.

Example usage:

f, err := os.Open("./delaware-latest.osm.pbf")
if err != nil {
	panic(err)
}
defer f.Close()

scanner := osmpbf.New(context.Background(), f, 3)
defer scanner.Close()

for scanner.Scan() {
	o := scanner.Object()
	// do something
}

scanErr := scanner.Err()
if scanErr != nil {
	panic(scanErr)
}

Note: Scanners are not safe for parallel use. One should feed the objects into a channel and have workers read from that.