6257ddba78
The big change is that the GeoJSON package has been completely rewritten to fix a few of geometry calculation bugs, increase performance, and to better follow the GeoJSON spec RFC 7946. GeoJSON updates - A LineString now requires at least two points. - All json members, even foreign, now persist with the object. - The bbox member persists too but is no longer used for geometry calculations. This is change in behavior. Previously Tile38 would treat the bbox as the object's physical rectangle. - Corrections to geometry intersects and within calculations. Faster spatial queries - The performance of Point-in-polygon and object intersect operations are greatly improved for complex polygons and line strings. It went from O(n) to roughly O(log n). - The same for all collection types with many children, including FeatureCollection, GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon. Codebase changes - The pkg directory has been renamed to internal - The GeoJSON internal package has been moved to a seperate repo at https://github.com/tidwall/geojson. It's now vendored. Please look out for higher memory usage for datasets using complex shapes. A complex shape is one that has 64 or more points. For these shapes it's expected that there will be increase of least 54 bytes per point.
215 lines
4.9 KiB
Markdown
215 lines
4.9 KiB
Markdown
# geohash
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Go [geohash](https://en.wikipedia.org/wiki/Geohash) library offering encoding
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and decoding for string and integer geohashes.
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[](http://godoc.org/github.com/mmcloughlin/geohash)
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[](https://travis-ci.org/mmcloughlin/geohash)
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[](https://coveralls.io/r/mmcloughlin/geohash)
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[](https://goreportcard.com/report/github.com/mmcloughlin/geohash)
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## Install
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Fetch the package with
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```
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go get github.com/mmcloughlin/geohash
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```
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And import it into your programs with
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```go
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import "github.com/mmcloughlin/geohash"
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```
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## Usage
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#### func Decode
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```go
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func Decode(hash string) (lat, lng float64)
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```
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Decode the string geohash to a (lat, lng) point.
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#### func DecodeCenter
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```go
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func DecodeCenter(hash string) (lat, lng float64)
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```
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DecodeCenter decodes the string geohash to the central point of the bounding
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box.
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#### func DecodeInt
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```go
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func DecodeInt(hash uint64) (lat, lng float64)
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```
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DecodeInt decodes the provided 64-bit integer geohash to a (lat, lng) point.
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#### func DecodeIntWithPrecision
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```go
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func DecodeIntWithPrecision(hash uint64, bits uint) (lat, lng float64)
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```
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DecodeIntWithPrecision decodes the provided integer geohash with bits of
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precision to a (lat, lng) point.
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#### func Encode
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```go
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func Encode(lat, lng float64) string
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```
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Encode the point (lat, lng) as a string geohash with the standard 12 characters
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of precision.
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#### func EncodeInt
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```go
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func EncodeInt(lat, lng float64) uint64
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```
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EncodeInt encodes the point (lat, lng) to a 64-bit integer geohash.
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#### func EncodeIntWithPrecision
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```go
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func EncodeIntWithPrecision(lat, lng float64, bits uint) uint64
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```
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EncodeIntWithPrecision encodes the point (lat, lng) to an integer with the
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specified number of bits.
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#### func EncodeWithPrecision
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```go
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func EncodeWithPrecision(lat, lng float64, chars uint) string
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```
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EncodeWithPrecision encodes the point (lat, lng) as a string geohash with the
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specified number of characters of precision (max 12).
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#### func Neighbor
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```go
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func Neighbor(hash string, direction Direction) string
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```
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Neighbor returns a geohash string that corresponds to the provided geohash's
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neighbor in the provided direction
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#### func NeighborInt
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```go
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func NeighborInt(hash uint64, direction Direction) uint64
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```
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NeighborInt returns a uint64 that corresponds to the provided hash's neighbor in
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the provided direction at 64-bit precision.
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#### func NeighborIntWithPrecision
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```go
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func NeighborIntWithPrecision(hash uint64, bits uint, direction Direction) uint64
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```
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NeighborIntWithPrecision returns a uint64s that corresponds to the provided
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hash's neighbor in the provided direction at the given precision.
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#### func Neighbors
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```go
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func Neighbors(hash string) []string
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```
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Neighbors returns a slice of geohash strings that correspond to the provided
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geohash's neighbors.
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#### func NeighborsInt
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```go
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func NeighborsInt(hash uint64) []uint64
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```
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NeighborsInt returns a slice of uint64s that correspond to the provided hash's
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neighbors at 64-bit precision.
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#### func NeighborsIntWithPrecision
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```go
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func NeighborsIntWithPrecision(hash uint64, bits uint) []uint64
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```
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NeighborsIntWithPrecision returns a slice of uint64s that correspond to the
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provided hash's neighbors at the given precision.
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#### type Box
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```go
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type Box struct {
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MinLat float64
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MaxLat float64
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MinLng float64
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MaxLng float64
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}
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```
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Box represents a rectangle in latitude/longitude space.
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#### func BoundingBox
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```go
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func BoundingBox(hash string) Box
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```
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BoundingBox returns the region encoded by the given string geohash.
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#### func BoundingBoxInt
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```go
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func BoundingBoxInt(hash uint64) Box
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```
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BoundingBoxInt returns the region encoded by the given 64-bit integer geohash.
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#### func BoundingBoxIntWithPrecision
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```go
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func BoundingBoxIntWithPrecision(hash uint64, bits uint) Box
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```
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BoundingBoxIntWithPrecision returns the region encoded by the integer geohash
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with the specified precision.
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#### func (Box) Center
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```go
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func (b Box) Center() (lat, lng float64)
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```
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Center returns the center of the box.
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#### func (Box) Contains
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```go
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func (b Box) Contains(lat, lng float64) bool
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```
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Contains decides whether (lat, lng) is contained in the box. The containment
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test is inclusive of the edges and corners.
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#### func (Box) Round
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```go
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func (b Box) Round() (lat, lng float64)
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```
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Round returns a point inside the box, making an effort to round to minimal
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precision.
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#### type Direction
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```go
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type Direction int
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```
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Direction represents directions in the latitute/longitude space.
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```go
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const (
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North Direction = iota
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NorthEast
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East
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SouthEast
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South
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SouthWest
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West
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NorthWest
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)
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```
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Cardinal and intercardinal directions
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