anchor.diff:  }
   
   function createCards(data) {
  +  $('.card').remove()
  +
     var card = contributions.select('.contributions_content')
       .selectAll('div')
       .data(data)
  
positive.code: var current_user_id = <%= current_user.id %>;
  var format_date = d3.timeFormat("%Y-%m-%d");
  
  var now = new Date;
  var px, py, vx, vy, offsetX, offsetY, maxVelocity = 8;
  
  
negative.code:   .range([-5, 5])
    .domain([0, data.length]);
  
  var nodes = createNodes(viewdata);
  
  var collisionForce = rectCollide()
    .size(function (d) { return [d.width, d.height] });
  