title: D3 change the charge of a single node
body: <p>When I click on a node, my node get bigger, and as it's now bigger, I would like his charge to repulse other node even more. How can I change the charge of a node ?</p>
  
  <p>Code excerpt:</p>
  
  <pre><code>[...]
  
  //draw new graph
  d3.json(file, function(error, graph) {
  
  force
  .nodes(graph.nodes)
  .links(graph.links)
  .start();
  
  var nodeCircle = node.append("circle")
  .attr("id", function(d) { return "node"+d.id })
  .attr("class", function(d) {return "node "+d.nodeclass; })
  .attr("r", 8) // R = Radius of node
  .style("fill", function(d) { return d.color; }) // Will overwrite CSS style
  .on("click",function(d) {
  
      //When CTRL key is pressed ....
      if (d3.event.ctrlKey) {
          if(d3.select(this).attr('r')==8){
              d3.select(this).attr('r', 12);
              //ToDo: node Charge = -1000
          }else{
              d3.select(this).attr('r', 8);
              //ToDo: node Charge = -500
          }
      }
  
  }).call(force.drag);
  [...]
  </code></pre>