oh-snap

Snap points to nearest point in a different set.

Installation

Install via npm:

npm install oh-snap

Usage

snap(points,snapTo[,maxDistance])

points is a GeoJSON feature collection of points.

snapTo is another GeoJSON feature collection of points.

maxDistance is an optional maximum distance, in meters (the default is no maximum). If specified, a point in points will only be counted as being at the nearest point in snapTo if it's less than maxDistance meters away.

Example

Let's say you have a GeoJSON collection of points where car crashes happened, and a GeoJSON collection of points for intersections, and you want to get a list of intersections with the number of crashes at/near each.

var snap = require("oh-snap");

//crashes is a GeoJSON FeatureCollection of points
//intersections is another GeoJSON FeatureCollection of points

var result = snap(crashes,intersections);

result will be another GeoJSON FeatureCollection with the same points as intersections. Each one will have one new property, called snapped:

snapped: {
  count: 4,
  details: [{...},{...},{...},{...}]
}

That means 4 points in crashes were closest to this intersection. details is an array of those four crashes' properties, in case you want it.