README
¶
go-geoindex
A simple in-memory geoindex for Go, based on the geohash-int library.
Proximity search largely based on the StackExchange discussion: http://gis.stackexchange.com/questions/18330/would-it-be-possible-to-use-geohash-for-proximity-searches/92331#92331
Original geohash-int library: https://github.com/yinqiwen/geohash-int
The modified fork of the geohash-int: https://github.com/mattsta/geohash-int
Some more documentations: https://github.com/yinqiwen/ardb/blob/master/doc/spatial-index.md https://matt.sh/redis-geo#_how-it-works
Usage
Add location:
prop := []string{"property1", "property2"}
AddCoord(&GeoData{Latitude: -32.1, Longitude: 120.3, Name: "myLocationName", Properties: &prop})
Search locations at lat/long (-32.1, 120.3) within a 12 km bound:
locations := SearchBound(-32.2, 120.3, 12)
Get location details by ID. The ID is in the format {geohash}-{name} (included in search results):
locationId := "3139639761105107-myLocationName"
GetLocation(locationId)
Limitations
- Search bounds are approximate square, and become gradually curved as the area increases.
- Bound distance are approximate and does not take the flat polar region into account.
- Latitude/Longitude approximation:
- 1 deg latitude = 110.574 km
- 1 deg longitude = 111.320*cos(latitude) km
- This geohash based proximity search does not search across the boundary at the poles (0) and at the international date line (180/-180).
- Name of location should be unique for the same coordinate.
- Limited to 100 locations at the same coordinate.
Documentation
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Overview ¶
* Copyright (c) 2015, Ian Chan <icha024@gmail.com>. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of Redis nor the names of its contributors may be used * to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF * THE POSSIBILITY OF SUCH DAMAGE.
Index ¶
Constants ¶
const MAX_STEPS C.uint8_t = 26
Variables ¶
This section is empty.
Functions ¶
func AddLocation ¶
AddLocation data to search index.
Types ¶
type GeoData ¶
type GeoData struct {
// Must be unique
Id int
// Generated automatically
GeoHash uint64
// User must specify these
Latitude, Longitude float64
Properties *[]string
}
func GetLocation ¶
GetLocation data for a location ID.
func SearchLocations ¶
SearchLocations around latitude/longitude in bounded area (km) for known location points.
type GeoIdSlice ¶
type GeoIdSlice []*GeoData
GeoIdSlice sorted by ID
func (GeoIdSlice) Len ¶
func (s GeoIdSlice) Len() int
func (GeoIdSlice) Less ¶
func (s GeoIdSlice) Less(i, j int) bool
func (GeoIdSlice) Swap ¶
func (s GeoIdSlice) Swap(i, j int)
Source Files