README
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♫ around the world ♪
what
This library provides convenience functions for translating, geocoding, and calculating distances between geographical points. It is inspired by ruby's geokit and geokit-rails gems, and aims to make working with geographical data a little bit easier in golang.
documentation
You can read the documentation here.
usage
Import from github to get started!
package main
import("github.com/kellydunn/golang-geo"
"fmt")
func main() {
// Make a few points
p := geo.NewPoint(42.25, 120.2)
p2 := geo.NewPoint(30.25, 112.2)
// find the great circle distance between them
dist := p.GreatCircleDistance(p2)
fmt.Printf("great circle distance: %d\n", dist)
}
Currently, golang-geo provides the following functionality:
- Transposing a point for a given distance and bearing.
- Calculating the Great Circle Distance bewteen two points.
- Geocoding an address using Google Maps API or Open Street Maps API.
- Reverse Geocoding a Point using the same services.
- Querying for points within a radius using your own SQL data tables.
Keep in mind that you do not need to use SQL in order to perform simple Point operations and the only function that relies on SQL is PointsWithinRadius.
using SQL
As of 0.1.0, golang-geo will shift its scope of responsiblity with SQL management. The library will still support the functions exposed in its public API in the past, however, it will not concern itself so much with creating and maintaining *sql.DB connections as it has done in previous versions. It is suggested that if you are using geo.HandleWithSql that you should instead consider creating a geo.SQLMapper yourself by calling the newly introduced geo.NewSQLMapper method, which accepts a *sql.DB connection and a filepath to the configuration file used to inform golang-geo of your particular SQL setup.
That being said, geo.HandleWithSQL is configured to connect to a SQL database by reading a config/geo.yml file in the root level of your project. If it does not exist, it will use a Default SQL configuration that will use the postgres driver as described by lib/pq. The Default SQL configuration will attempt to connect as a user named "postgres" and with the password "postgres" to a database named "points".
examples of SQL database configurations
Here are some examples of valid config files that golang-geo knows how to process:
PostgreSQL
development:
driver: postgres
openStr: user=username password=password dbname=points sslmode=disable
table: points
latCol: lat
lngCol: lng
MySQL
development:
driver: mysql
openStr: points/username/password
table: points
latCol: lat
lngCol: lng
notes
golang-geocurrently only uses metric measurements to do calculations- The
$GO_ENVenvironment variable is used to determine which configuration group inconfig.ymlis to be used. For example, if you wanted to use the PostgreSQL configuration listed above, you could specifyGO_ENV=developmentwhich would readconfig.ymland use the configuration under the root-level keydevelopment.
installing older versions of golang-geo
With the advent of gopin.org, you can now install older versions of golang-geo! Consult CHANGELOG.md for the commit hash of the version you wish to build against.
roadmap
- More Tests!
- Redis / NOSQL Mapper
- Bing Maps?
- Add an abstraction layer for PostgreSQL earthdistance / PostGIS
testing
By default, golang-geo will attempt to run its test suite against a PostgreSQL database. However, you may run the tests with mocked SQL queries by specifying that you want to do so on the command line:
DB=mock GO_ENV=test go test
The $DB environment variable is used to specify which database you'd like to run the tests against. You may specify postgres, mysql, or mock. The Travis CI builds for this project currently runs against all of these when running the test suite.
contributing
- Fork the project
- Create a topic branch (preferably the in the
gitflowstyle offeature/,hotfix/, etc) - Make your changes and write complimentary tests to ensure coverage.
- Submit Pull Request (on develop) once the full test suite is passing.
- Pull Requests will then be reviewed by the maintainer and the community and hopefully merged!
Thanks!
Documentation
¶
Index ¶
Constants ¶
const ( DEFAULT_PGSQL_OPEN_STR = "user=postgres dbname=points sslmode=disable" DEFAULT_MYSQL_OPEN_STR = "points/root/" DEFAULT_TEST_OPEN_STR = "\"\"" )
const (
// According to Wikipedia, the Earth's radius is about 6,371km
EARTH_RADIUS = 6371
)
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Geocoder ¶
type Geocoder interface {
Geocode(query string) (*Point, error)
ReverseGeocode(p *Point) (string, error)
}
This interface describes a Geocoder, which provides the ability to Geocode and Reverse Geocode geographic points of interest. Geocoding should accept a string that represents a street address, and returns a pointer to a Point that most closely identifies it. Reverse geocoding should accept a pointer to a Point, and return the street address that most closely represents it.
type GoogleGeocoder ¶
type GoogleGeocoder struct{}
func (*GoogleGeocoder) Geocode ¶
func (g *GoogleGeocoder) Geocode(query string) (*Point, error)
Geocodes the passed in query string and returns a pointer to a new Point struct. Returns an error if the underlying request cannot complete.
func (*GoogleGeocoder) Request ¶
func (g *GoogleGeocoder) Request(params string) ([]byte, error)
Issues a request to the google geocoding service and forwards the passed in params string as a URL-encoded entity. Returns an array of byes as a result, or an error if one occurs during the process.
func (*GoogleGeocoder) ReverseGeocode ¶
func (g *GoogleGeocoder) ReverseGeocode(p *Point) (string, error)
Reverse geocodes the pointer to a Point struct and returns the first address that matches or returns an error if the underlying request cannot complete.
type MapQuestGeocoder ¶
type MapQuestGeocoder struct{}
A Geocoder that makes use of open street map's geocoding service
func (*MapQuestGeocoder) Geocode ¶
func (g *MapQuestGeocoder) Geocode(query string) (*Point, error)
Returns the first point returned by MapQuest's geocoding service or an error if one occurs during the geocoding request.
func (*MapQuestGeocoder) Request ¶
func (g *MapQuestGeocoder) Request(url string) ([]byte, error)
Issues a request to the open mapquest api geocoding services using the passed in url query. Returns an array of bytes as the result of the api call or an error if one occurs during the process.
func (*MapQuestGeocoder) ReverseGeocode ¶
func (g *MapQuestGeocoder) ReverseGeocode(p *Point) (string, error)
Returns the first most available address that corresponds to the passed in point. It may also return an error if one occurs during execution.
type Mapper ¶
This interface describes a Mapper, which should be a data storage mechanism that can execute interesting queries. Currently, mappers should be able to find points within a radius of an origin point.
type Point ¶
type Point struct {
// contains filtered or unexported fields
}
Represents a Physical Point in geographic notation [lat, lng].
func NewPoint ¶
Returns a new Point populated by the passed in latitude (lat) and longitude (lng) values.
func (*Point) BearingTo ¶ added in v0.2.0
Calculates the initial bearing (sometimes referred to as forward azimuth) Original Implementation from: http://www.movable-type.co.uk/scripts/latlong.html
func (*Point) GreatCircleDistance ¶
Calculates the Haversine distance between two points. Original Implementation from: http://www.movable-type.co.uk/scripts/latlong.html
func (*Point) PointAtDistanceAndBearing ¶
Returns a Point populated with the lat and lng coordinates of transposing the origin point the distance (in meters) supplied by the compass bearing (in degrees) supplied. Original Implementation from: http://www.movable-type.co.uk/scripts/latlong.html
type SQLConf ¶
type SQLConf struct {
// contains filtered or unexported fields
}
Provides a set of configuration variables that describe how to interact with a SQL database.
func GetSQLConf ¶
Attempts to read config/geo.yml, and creates a SQLConf as described therein. Returns the DefaultSQLConf if no config/geo.yml is found, or an error if one arises during the process of parsing the configuration file.
func GetSQLConfFromFile ¶ added in v0.1.0
Attempts to read from the passed in filename and creates a SQLconf as described therin. Retruns the DefaultSQLConf if the file cannot be found, or an error if one arises during the process of parsing the configuration file.
type SQLMapper ¶
type SQLMapper struct {
// contains filtered or unexported fields
}
A Mapper that uses Standard SQL Syntax to perform mapping functions and queries
func HandleWithSQL ¶
Retrieves the SQL configuration specified in config.yml that resides at the root level of the project. Returns a pointer to a SQLMapper if successful, or an error if there is an issue opening a database connection.
func NewSQLMapper ¶ added in v0.1.0
Creates and returns a pointer to a new geo.SQLMapper.
func (*SQLMapper) PointsWithinRadius ¶
Uses SQL to retrieve all points within the radius (in meters) passed in from the origin point passed in. Original implemenation from : http://www.movable-type.co.uk/scripts/latlong-db.html Returns a pointer to a sql.Rows as a result, or an error if one occurs during the query.
Source Files