grid-point-store

Fast 2D point insertions and spatial querying over a fixed grid.

Usage

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

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 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.
• (optional) types (Array[3]): a size-3 array of comparable storable type 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 installed, run

$ npm install grid-point-store

See Also

• kdb-tree-store
• geohash-point-store

License

ISC