![]() Without this constraint, outlier points can get selected even though the pointer isn't very close. This is useful for ensuring the returned point is close to the requested point. find returns undefined because the closest point is more than 5 away. find returns because this is the closest point and is within a distance of 20. ![]() find ( 60, 100, 5 ) // returns undefined You can also add a distance (as the third argument) so that only points within that distance are returned: quadtree. Given a coodinate x, y you can find the nearest point in the quadtree using. In the above example two points have been added: 50, 100 and 100, 100. You can then add single points to it using. You can create a quadtree by calling d3.quadtree(). With D3's quadtree module you can create a quadtree, add some points to it, then find the closest point within the quadtree to a given coordinate. Line charts can also benefit from quadtrees for picking points along a line. This can be an expensive operation but can be made more efficient using D3's quadtree module.Ī quadtree is a tree data structure that recursively divides an area into smaller and smaller areas and can make searching for items more efficient. You can make picking small items easier by searching for the closest item to the mouse pointer each time the mouse is moved.
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