localtimezone

README

github.com/albertyw/localtimezone

LatLong conversion to time zone. This is a fork of github.com/ugjka/go-tz.

Usage / Example

import localtimezone "github.com/albertyw/localtimezone/v2"

// Loading Zone for Line Islands, Kiritimati
tz, err := localtimezone.NewLocalTimeZone()
if err != nil {
    panic(err)
}
zone, err := tz.GetZone(localtimezone.Point{
    Lon: -157.21328, Lat: 1.74294,
})
if err != nil {
    panic(err)
}
fmt.Println(zone[0])

Uses simplified shapefile from timezone-boundary-builder

GeoJson Simplification done with orb.

Features

• The timezone shapefile is embedded in the build binary
• Supports overlapping zones
• You can load your own geojson shapefile if you want
• Sub millisecond lookup even on old hardware

Problems

• Shapefile is simplified using a lossy method so it may be innacurate along the borders
• This is purely in-memory. Uses ~50MB of ram

Updating data

Get the most current timezone release version at https://github.com/evansiroky/timezone-boundary-builder/tags

go run tzshapefilegen/main.go

Licenses

The code used to lookup the timezone for a location is licensed under the MIT License.

The data in timezone shapefile is licensed under the Open Data Commons Open Database License (ODbL).

Documentation

Overview

Package localtimezone provides timezone lookup for a given location

Features

* The timezone shapefile is embedded in the build binary using go-bindata

* Supports overlapping zones

* You can load your own geojson shapefile if you want

* Sub millisecond lookup even on old hardware

Problems

* The shapefile is simplified using a lossy method so it may be innacurate along the borders

* This is purely in-memory. Uses ~50MB of ram

Index

• Constants
• Variables
• type Feature
• type FeatureCollection
• type Geometry
  • func (g *Geometry) UnmarshalJSON(data []byte) (err error)
• type LocalTimeZone
  • func NewLocalTimeZone() (LocalTimeZone, error)
  • func NewMockLocalTimeZone() LocalTimeZone
• type Point

Constants

const MockTimeZone = "America/Los_Angeles"

MockTimeZone is the timezone that is always returned from the NewMockLocalTimeZone client

const TZBoundaryVersion = "2022f"

TZBoundaryVersion is the version of tzdata that was used to generate timezone boundaries

Variables

var ErrNoZoneFound = errors.New("no corresponding zone found in shapefile")

ErrNoZoneFound is returned when a zone for the given point is not found in the shapefile

var ErrOutOfRange = errors.New("point's coordinates out of range")

ErrOutOfRange is returned when latitude exceeds 90 degrees or longitude exceeds 180 degrees

var MockTZShapeFile []byte

MockTZShapeFile is similar to TZShapeFile but maps the entire world to the timezone America/Los_Angeles. This data is a small json blob compressed with gzip. It is meant for testing.

var TZShapeFile []byte

TZShapeFile is the data containing geographic shapes for timezone borders. This data is a large json blob compressed with gzip.

Types

type Feature

type Feature struct {
	Geometry   Geometry
	Properties struct {
		Tzid string
	}
}

Feature maps a Geometry with TZids

type FeatureCollection

type FeatureCollection struct {
	Features []*Feature
}

FeatureCollection is a set of Features

type Geometry

type Geometry struct {
	Coordinates   [][]Point
	BoundingBoxes [][]Point
}

Geometry represents a set of points that draw a geographic geometry

func (*Geometry) UnmarshalJSON

func (g *Geometry) UnmarshalJSON(data []byte) (err error)

UnmarshalJSON parses json data into a geometry

type LocalTimeZone

type LocalTimeZone interface {
	GetZone(p Point) (tzid []string, err error)
}

LocalTimeZone is a client for looking up time zones by Points

func NewLocalTimeZone

func NewLocalTimeZone() (LocalTimeZone, error)

NewLocalTimeZone creates a new LocalTimeZone with real timezone data The client is threadsafe

func NewMockLocalTimeZone

func NewMockLocalTimeZone() LocalTimeZone

NewMockLocalTimeZone creates a new LocalTimeZone that always returns America/Los_Angeles as the timezone The client is threadsafe

type Point

type Point struct {
	Lon float64
	Lat float64
}

Point describes a location by Latitude and Longitude