The d3.voronoi module has the handyvoronoi.find(x,y,r)(#17) method, which returns the closest site to a given point, which is very useful for a number of applications. But what if we wanted all the sites within a given radius?

I've been working on a few things where a built in method would be handy, but also saw a questionquestionon StackOverflow yesterday on the same topic that got me thinking, if we have a method to find the closest site, why not a method to find all sites within a given radius?

I've mocked up a potential method here, it takes the same parameters asvoronoi.find,but spits out an array of sites rather than a single one.

findAll: function(x, y, r) {
var diagram = this, center = diagram.find(x,y,r); // use the existing method to find central point
if(!center) return [];
var queue = [center], checked = []; // queue holds cells within the boundary

for(var i = 0; i < queue.length; i++) {
checked.push(queue[i].index); // don't check any cell twice

// find neighbors of current item:
var edges = diagram.cells[queue[i].index].halfedges;
var neighbors = edges.map(function(e) {
return (diagram.edges[e].left == queue[i])? diagram.edges[e].right: diagram.edges[e].left;
})

// for each neighbor, see if it is within the radius (and unchecked), if so, add to queue
neighbors.forEach(function(n) {
if(n && checked.indexOf(n.index) == -1) {
var dx = n[0] - x, dy = n[1] - y;
var d2 = dx*dx+dy*dy;
(d2>r*r)? checked.push(n.index): queue.push(n);
}
})
}
return queue;
}

Andhere'sa demonstration.

Granted, this implementation leads to some cells potentially being examined more than once (first through the use ofvoronoi.find()to get the initial cell); consequently, it could be re-worked to include a slightly modified voronoi.find() method to get started.

But, this might be getting ahead of myself. Is there value in including such a method in d3.voronoi?