geohash

Documentation

Index

• Constants
• Variables
• func DecodeAreaToLongLat(area *Area) (float64, float64)
• func DecodeToLongLatWGS84(bits uint64) (float64, float64)
• func DistBetweenGeoHashWGS84(hash0 uint64, hash1 uint64) float64
• func EncodeToBase32(hash uint64) []byte
• func EncodeWGS84(longitude, latitude float64) (uint64, error)
• func GetDistance(lon0d, lat0d, lon1d, lat1d float64) float64
• type Area
  • func DecodeWGS84(bits uint64) *Area
• type HashBits
  • func Encode(longRange, latRange *Range, longitude, latitude float64, step uint8) (HashBits, error)
  • func (hash *HashBits) Clean()
  • func (hash HashBits) IsZero() bool
• type Neighbors
  • func GetNeighbors(hash HashBits) *Neighbors
• type Point
• type Radius
  • func GetAreasByRadiusWGS84(longitude, latitude, radius float64) (*Radius, error)
• type Range

Constants

const (
	/* These are constraints from EPSG:900913 / EPSG:3785 / OSGEO:41001
	We can't geocode at the north/south pole.*/
	WGS84_LAT_MIN  = -85.05112878
	WGS84_LAT_MAX  = 85.05112878
	WGS84_LONG_MIN = -180
	WGS84_LONG_MAX = 180

	/* Use 26*2 = 52bits to encode a position in WGS84, the precision is 0.6m.*/
	WGS84_GEO_STEP = 26
)

const (
	MERCATOR_MAX float64 = 20037726.37

	// Earth's quatratic mean radius for WGS-84
	EARTH_RADIUS_IN_METERS float64 = 6372797.560856

	D_R = (math.Pi / 180.0)
)

Variables

var (
	WGS84_LONG_RANGE = &Range{Max: WGS84_LONG_MAX, Min: WGS84_LONG_MIN}
	WGS84_LAT_RANGE  = &Range{Max: WGS84_LAT_MAX, Min: WGS84_LAT_MIN}
)

var (
	ErrPositionOutOfRange = errors.New("position out of range of WGS84")
	ErrStepOutOfRange     = errors.New("geohash encode step must less-equal than 32 and greater than 0")
)

Functions

func DecodeAreaToLongLat

func DecodeAreaToLongLat(area *Area) (float64, float64)

func DecodeToLongLatWGS84

func DecodeToLongLatWGS84(bits uint64) (float64, float64)

func DistBetweenGeoHashWGS84

func DistBetweenGeoHashWGS84(hash0 uint64, hash1 uint64) float64

func EncodeToBase32

func EncodeToBase32(hash uint64) []byte

func EncodeWGS84

func EncodeWGS84(longitude, latitude float64) (uint64, error)

func GetDistance

func GetDistance(lon0d, lat0d, lon1d, lat1d float64) float64

Calculate distance using haversin great circle distance formula.

Types

type Area

type Area struct {
	Hash      HashBits
	Longitude Range
	Latitude  Range
}

func DecodeWGS84

func DecodeWGS84(bits uint64) *Area

type HashBits

type HashBits struct {
	Bits uint64
	Step uint8
}

func Encode

func Encode(
	longRange, latRange *Range,
	longitude, latitude float64,
	step uint8) (HashBits, error)

func (*HashBits) Clean

func (hash *HashBits) Clean()

func (HashBits) IsZero

func (hash HashBits) IsZero() bool

type Neighbors

type Neighbors struct {
	North     HashBits
	East      HashBits
	West      HashBits
	South     HashBits
	NorthEast HashBits
	SouthEast HashBits
	NorthWest HashBits
	SouthWest HashBits
}

func GetNeighbors

func GetNeighbors(hash HashBits) *Neighbors

type Point

type Point struct {
	Longitude float64
	Latitude  float64
}

type Radius

type Radius struct {
	Area
	Hash HashBits
	*Neighbors
}

func GetAreasByRadiusWGS84

func GetAreasByRadiusWGS84(longitude, latitude, radius float64) (*Radius, error)

type Range

type Range struct {
	Max float64
	Min float64
}