## leaflet-knn

Next-nearest neighbor searches with [sphere-knn](https://github.com/darkskyapp/sphere-knn),
with a [Leaflet](http://leafletjs.com/)-friendly API.

## example

```js
var gj = L.geoJson(GEOJSON_DATA);
var nearest = leafletKnn(gj).nearest(L.latLng(38, -78), 5);
```

## using it

    wget https://raw.github.com/mapbox/leaflet-knn/master/leaflet-knn.min.js

(or without the `.min.` if you want more debugging power)

With [browserify](https://github.com/substack/node-browserify)

    npm install leaflet-knn

## api

### `var index = leafletKnn(layer)`

Generates a lookup function from an `L.geoJson` layer object.

API is the same as the [sphere-knn](https://github.com/darkskyapp/sphere-knn) API
for the lookup function, but with nice handling for `l.latLng`

### `index.nearest(point: L.LatLng or [lon, lat], n, max_distance)`

Given a point, find the nearest points to it. If the index contains multi-point
features, like lines, polygons, and so on, it returns _points in those features_
and can return more than one point in each feature.

* point: L.LatLng or [lon, lat], index, [max points: int], [max distance: number])`
* n: the maximum number of points returned from the search
* max_distance: maximum distance in meters

### `index.nearestLayer(point: L.LatLng or [lon, lat], n, max_distance)`

Like `nearest`, except multiple matches in the same multi-point feature are
collapsed, so the array returned has one result per layer.

* point: L.LatLng or [lon, lat], index, [max points: int], [max distance: number])`
* n: the maximum number of points returned from the search
* max_distance: maximum distance in meters