spatial-db-ngt

JSON db with n-dimensional nearest neighbors search, combining NGT vector search with JSON stored in leveldb.

Basically ngt-tool with JSON payloads. Similar to spatial-db but faster.

• This tool is experimental

Installation

First install ngt.

Then install with npm.

npm i spatial-db-ngt

Usage

var SpatialDbNgt = require('spatial-db-ngt');
var ngtt = require('ngt-tool');

//create new spatial-db-ngt
var numDimensions = 5;
var sdb = new SpatialDbNgt('mytest',numDimensions);

//add 100 random items with json - one by one
for(var i=0;i<100;i++){
    var itemKey = "my_item"+i;
    var itemJSON = {"something":"stuff"+i};
    var randomVector = ngtt.generateVector(numDimensions); //array of random floats
    sdb.addItemToDb_sync(itemKey, itemJSON, randomVector);

    //note - adding multiple items with the same key will produce
    //multiple vectors associated with the same json object.
    //eg the json data is overwritten but vectors are permanent.
}

//add items, bulk
var keys = ["key1","key2"];
var jsonItems = [{"some1": "json1"},{"some2":"json2"}];
var vectors = ngtt.generateVectorList(numDimensions,jsonItems.length); //array of vectors; each vector is array of floats
sdb.addItemsToDb_sync(keys, jsonItems, vectors);

//update item json
sdb.updateItemJson_sync("my_item32", {"newstuff":"is here now"});

//get item from db
console.log(sdb.getItemFromDb_sync("my_item32"));

//result
/*
{
  vector: [
    0.5486296150852892,
    0.5829361650362115,
    0.5297864223424096,
    0.49587874692720013,
    0.8087344422687666
  ],
  json: { newstuff: 'is here now' },
  ngtId: 35,
  key: 'my_item32'
}
 */


//search for nearest neighbors 

var randomSearchVector = ngtt.generateVector(numDimensions); //array of random floats
var numberOfResults = 2;
var radius = 10.0;

console.log(sdb.searchDb_nearestNeighbors_sync(randomSearchVector, numberOfResults, radius));

//result:
/*
[
    {
        vector: [
            0.18625948240313495,
            0.7975673245218937,
            0.3348365678471359,
            0.16693183181406512,
            0.29184773086562577
        ],
        json: { some1: 'json1' },
        ngtId: 1,
        distance: 0.819544
    },
    {
        vector: [
            0.055458120172628966,
            0.9540835249844943,
            0.2664088896698613,
            0.16366906181043261,
            0.7774182161406313
        ],
        json: { some2: 'json2' },
        ngtId: 2,
        distance: 0.82182
    }
]*/

Async functions

Remove _sync from the end of function names to get async versions with callback(err, result) as the final parameter.

Where is the data stored?

If you named your database "mytest", then ngt data is stored in a folder called ./mytest_ngt_db and leveldb data goes to a folder named ./mytest_level_db.

What is NGT?

Yahoo Japan's Neighborhood Graph and Tree for Indexing High-dimensional Data

Note: spatial-db-ngt is not affiliated with Yahoo or Yahoo Japan.

See Also

• spatial-db
• ngt-tool