bnfinet / timezonelookup

Timezone lookup API for GPS Coordinates based from GeoJSON

Timezone lookup

Is a timezone lookup API for GPS Coordinates to Timezone based on GeoJSON Polygon and Multipolygon files.

Source Data

Source files can be obtained at https://github.com/evansiroky/timezone-boundary-builder

Performance

Performance is significantly improved between release v1 and release v2 due to the underlying data structure. Timezone database is approxiamtely 50mb in size and lookups range between 50 - 200 microseconds. Recent verion uses an RTree as well as a Memory mapped timezone database for reduced latency and increased throughput.

[]Benchmarks still need to be written.

Authors

Appreciate all who have contributed with Pull Requests and Issues. We eagerly welcome suggestions and PRs.

Rtree source design by Josh Backer tidwall

Example

Build program

go build -o timezone cmd/main.go 

Download datasource and build timezone database ~50mb

./timezone -build

Test query for San Fransisco, United States (Etc/GMT+8)

./timezone -search -lat=37.7749 -lng=-122.4194

Release V2.0 and forward

Based on custom backing that loads data as memory mapped data.

package main

import (
	"fmt"

	timezone "github.com/evanoberholster/[email protected]"
)

func main() {
	var tzc timezone.Timezonecache
	f, err := os.Open("timzone.data")
	if err != nil {
		return timezone.Result{}, err
	}
	defer f.Close()
	if err = tzc.Load(f); err != nil {
		return timezone.Result{}, err
	}
	defer tzc.Close()

	lat := 37.7749
	lng := -122.4194

	result := tzc.Search(lat, lng)
	fmt.Println(result)
}

Release V1.0 and prior

Based on JSON, MsgPack, Protobuf or Cap'n'Proto encodings with boltDB backend

Intructions for V1.0

1. Download data from: https://github.com/evansiroky/timezone-boundary-builder/releases
2. go get github.com/evanoberholster/[email protected]
3. go build github.com/evanoberholster/timezoneLookup/cmd/timezone.go
4. timezone -json "jsonfilename" -db=timezone -type=(memory or boltdb)
5. go run example.go

package main
import (
	"fmt"
	timezone "github.com/evanoberholster/[email protected]"
)
var tz timezone.TimezoneInterface

func main() {
	tz, err := timezone.LoadTimezones(timezone.Config{
		DatabaseType:"boltdb", // memory or boltdb
		DatabaseName:"timezone", // Name without suffix
		Snappy: true,
		Encoding: "msgpack", // json or msgpack
	})
	if err != nil {
		fmt.Println(err)
	}

	res, err := tz.Query(timezone.Coord{
			Lat: 5.261417, Lon: -3.925778,})
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println("Query Result: ", res)

	tz.Close()
}