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https://github.com/hackergrrl/grid-point-store
Fast 2D point insertions and spatial querying over grid of fixed size cells.
https://github.com/hackergrrl/grid-point-store
Last synced: 1 day ago
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Fast 2D point insertions and spatial querying over grid of fixed size cells.
- Host: GitHub
- URL: https://github.com/hackergrrl/grid-point-store
- Owner: hackergrrl
- Created: 2017-08-18T19:18:01.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2018-02-03T01:07:27.000Z (over 6 years ago)
- Last Synced: 2024-05-13T16:25:50.139Z (5 months ago)
- Language: JavaScript
- Homepage:
- Size: 33.2 KB
- Stars: 11
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# grid-point-store
> Fast 2D point insertions and spatial querying over a fixed grid.
## Usage
```js
var GeoStore = require('grid-point-store')
var memdb = require('memdb')
var store = GeoStore({
store: memdb(),
zoomLevel: 14
})
var pending = 10
var spread = 0.1 // ~10km
function insert () {
if (!pending) return check()
var x = Math.random() * spread - spread / 2
var y = Math.random() * spread - spread / 2
var loc = parseInt(Math.random().toString().substring(15))
store.insert([y, x], loc, function (err) {
pending--
insert()
})
}
insert()
function check () {
var bbox = [ [ -1, 1 ], [ -1, 1 ] ]
var q = store.queryStream(bbox)
q.on('data', function (pt) {
console.log('data', pt)
})
}
```
outputs
```
data { point: 0.021974959554208737, -0.036042143780795316 }, value: 486 }
data { point: 0.01731653112725491, 0.04090562190958498 }, value: 398 }
data { point: -0.0059460250360946695, -0.027539338463307098 }, value: 3 }
data { point: -0.037361984139033334, -0.002493949477883839 }, value: 3795 }
data { point: -0.043988977366412524, -0.03764949331648002 }, value: 4426 }
data { point: -0.045367303981649724, -0.03634679567215611 }, value: 356 }
data { point: 0.023642309425643854, 0.017864021495420324 }, value: 81 }
data { point: -0.031037061354238983, 0.006035785956166738 }, value: 407 }
data { point: 0.03480660267412845, 0.032896501435967895 }, value: 46 }
data { point: 0.02960226742605787, 0.027872606373290573 }, value: 788 }
```
## API
```js
var GeoStore = require('grid-point-store')
```
### var store = GeoStore(opts)
Create a new point store `store` backed by the LevelUP instance `leveldb`.
Valid `opts` include:
- (required) `store`: an [LevelUP](https://github.com/Level/LevelUP) compatible
database instance.
- (optional) `zoomLevel` (integer): an OSM-style zoom level to divide the world
up by. `zoomLevel == 1` captures the entire world in 1 tile, `2` in 4 tiles,
`3` in 16 tiles, and so forth. Read more on [OSM zoom
levels](wiki.openstreetmap.org/wiki/Zoom_levels).
- (optional) `types` (Array[3]): a size-3 array of [comparable storable type](https://github.com/substack/comparable-storable-types) strings for the
X and Y components, with the 3rd being the value format. Defaults to `['float64', 'float64', 'uint32']`.
### store.insert([x, y], value, cb)
Insert a point `[x, y]` with value `value` into the store.
`cb` is a callback that will be called as `cb(err)` if an error occurs, or
`cb(null)` if the insertion succeeded.
### store.query(bbox[, opts], cb)
Query a rectangular region for points. `cb` is called with the array of points
in the region.
`bbox` is an array of arrays of the form
```
[
[ minX, maxX ],
[ minY, maxY ]
]
```
### var stream = store.queryStream(bbox)
Query a rectangular region for points. Returns the Readable stream `stream`.
### store.remove(pt[, opts], cb)
Deletes points at `pt` (a size-2 array of the form `[x, y]`).
Valid `opts` include
- (optional) `opts.value`: Only delete points at this location with this
specific value.
`cb` is a callback that will be called as `cb(err)` if an error occurs, or
`cb(null)` if the deletion succeeded.
## Caveats
- Missing: stream backpressure on `queryStream`
PRs very welcome! :heart:
## Install
With [npm](https://npmjs.org/) installed, run
```
$ npm install grid-point-store
```
## See Also
- [kdb-tree-store](https://github.com/peermaps/kdb-tree-store)
- [geohash-point-store](https://github.com/noffle/geohash-point-store)
## License
ISC