title: How to find all points which distance to a given point lie in a small interval (python)?
body: <p>I have a 3D point cloud P and a point p, I want to find all points q such that <code>d-eps &lt; ||q-p|| &lt; d+eps</code>, where <code>d</code> and <code>eps</code> are given. What is the most efficient way to do such a search in python ?</p>
  <p>Usually I'd use a spherical neighbours query with a KD-Tree however this doesn't seem efficient, especially when d is much bigger than eps</p>