README
¶
GeoHashi
Geohash library for Go, optimised for performance. Inspired by geohash-int.
Examples
Encode coordinates:
func Encode() {
lat, lon := 51.52463, -0.08411
hash1 := geohashi.EncodeWithPrecision(lat, lon, 10)
fmt.Printf("%d (%d)\n", hash1, hash1.Precision())
hash2 := geohashi.EncodeWithPrecision(lat, lon, 20)
fmt.Printf("%d (%d)\n", hash2, hash2.Precision())
}
Decode hash:
func Decode() {
hash := geohashi.Hash(90072520759854475)
area := hash.Decode()
lat, lon := area.Center()
fmt.Printf("%.5f,%.5f\n", lat, lon)
fmt.Println(area.Contains(51.52463, -0.08411))
}
Precision
This library allows you to select the precision of the hash you want to create, up to a maximum of 26 bits.
The following table shows the maximum uncertainty (at the equator) for a given bit-precision:
| Bits | Uncertainty |
|---|---|
| 26 | ±0.35m |
| 25 | ±0.65m |
| 24 | ±1.3m |
| 23 | ±2.6m |
| 22 | ±5.3m |
| 21 | ±11m |
| 20 | ±21m |
| 19 | ±42m |
| 18 | ±84m |
| 17 | ±170m |
| 16 | ±340m |
| 15 | ±680m |
| 14 | ±1400m |
| 13 | ±2700m |
| 12 | ±5400m |
| 11 | ±11000m |
| 10 | ±22000m |
| 9 | ±43000m |
| 8 | ±86000m |
| 7 | ±170000m |
| 6 | ±350000m |
| 5 | ±690000m |
| 4 | ±1400000m |
| 3 | ±2800000m |
| 2 | ±5400000m |
| 1 | ±10000000m |
Documentation
¶
Index ¶
Examples ¶
Constants ¶
const ( LatMin = -85.05112878 LatMax = -LatMin LonMin = -180.0 LonMax = -LonMin PrecisionMin = 1 PrecisionMax = 26 )
Limits from EPSG:900913 / EPSG:3785 / OSGEO:41001
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Area ¶
type Area struct{ MinLat, MaxLat, MinLon, MaxLon float64 }
Area is a rectangle area defined through a min and max lat/lon
type Hash ¶
type Hash uint64
A Hash a numeric geohash value
Example ¶
package main
import (
"fmt"
"github.com/bsm/geohashi"
)
func main() {
hash := geohashi.Hash(90072520759854475)
area := hash.Decode()
lat, lon := area.Center()
fmt.Printf("%.5f,%.5f\n", lat, lon)
fmt.Println(area.Contains(51.52463, -0.08411))
}
Output: 51.52460,-0.08394 true
func Encode ¶
Encode converts a lat/lon to an geohash with maximum precision
Example ¶
package main
import (
"fmt"
"github.com/bsm/geohashi"
)
func main() {
lat, lon := 51.52463, -0.08411
hash1 := geohashi.EncodeWithPrecision(lat, lon, 10)
fmt.Printf("%d (%d)\n", hash1, hash1.Precision())
hash2 := geohashi.EncodeWithPrecision(lat, lon, 20)
fmt.Printf("%d (%d)\n", hash2, hash2.Precision())
}
Output: 45035996274208702 (10) 90072520759854475 (20)
func EncodeWithPrecision ¶
EncodeWithPrecision converts a lat/lon to an numeric geohash
func (Hash) Children ¶
Children zooms in, returning four child hashes, in the following order SW, SE, NW, NE. This function may return nil if unable to zoom in further
func (Hash) MoveX ¶
MoveX moves n steps east (positive number) or west (negative number) and returns the resulting hash
func (Hash) MoveY ¶
MoveY moves n steps north (positive number) or south (negative number) and returns the resulting hash
Source Files