Better (non-linear) binning

Question

The last question I asked concerned how to bin data by x co-ordinate. The solution was simple and elegant, and I\'m ashamed I didn\'t see it. This question may be harder (

Answer 1

I've never used matlab but from looking at your previous question I suspect your looking for something along the lines of a Kdtree or a variation.

Clarification: Since there seems to be some confusion about this I think an pseudocode example is in order.

// Some of this shamelessly borrowed from the wikipedia article
function kdtree(points, lower_bound, upper_bound) {
    // lower_bound and upper_bound are the boundaries of your bucket
    if(points is empty) {
        return nil
    }
    // It's a trivial exercise to control the minimum size of a partition as well
    else {
        // Sort the points list and choose the median element
        select median from points.x

        node.location = median;

        node.left = kdtree(select from points where lower_bound < points.x <= median, lower_bound, median);
        node.right = kdtree(select from points where median < points.x <= upper_bound, median, upper_bound);

        return node
    }
}

kdtree(points, -inf, inf)

// or alternatively

kdtree(points, min(points.x), max(points.x))