ject.y;
    }

    function dragged(event) {
      event.subject.fx = event.x;
      event.subject.fy = event.y;
    }

    function dragended(event) {
      if (!event.active) simulation.alphaTarget(0);
      event.subject.fx = null;
      event.subject.fy = null;
    }

    return d3.drag()
      .on("start", dragstarted)
      .on("drag", dragged)
      .on("end", dragended);
  }

  // Update positions in the animation loop
  function ticked() {
    // Always select current DOM elements for links and nod