Select a one- or two-dimensional region using the mouse or touch.

Kerry Rodden

Brushable parallel coordinates

Quadtree brush

Mike Bostock

Focus + Context

brush.filter

Mona Lisa Histogram

Click to Recenter Brush

Brush Snapping (Transitions)

Ordinal Brushing

Empty Brush Selection

Brush Handles

Brush Snapping

Double-Click to Brush

Brushable scatterplot matrix

Brush transitions

Brushable scatterplot

D3 Documentation

d3-brush

Two-dimensional recursive spatial subdivision.

d3-quadtree

Suggest to add ISC License please. Thanks!

Curran Kelleher

It's probably generally faster if you just bulk add points once you're in an interior quad, right? As at https://observablehq.com/@bmschmidt/quadtree-brush-optimization

Benjamin Schmidt

I think you're right! (But I disagree on the choice of pink 😅)

Wouldn't this be easier if quadtree.visit accepted a starting node?
as in https://observablehq.com/d/312fcfaca223e27f

I’m also wondering if quads should be iterable over the contained data.

Yes that would be rad. Some working code based on the previous visit(callback, startNode), to test the API:

node[Symbol.iterator] = function*() {
  const nodes = [];
  visit.apply(quadtree, [
    node => void (node.data && nodes.push(node)),
    node
  ]);
  yield* nodes;
};

Usage:
> for (const { data } of node) data.immediate = true;

(the actual implementation would not store the nodes but yield them immediately)

Here’s a prototype: https://observablehq.com/d/526b5aaee6bbcf5b