title: Show data on mouseover of circle
body: <p>I have a set of data that I am plotting in a scatter.  When I mouseover one of the circles I would like it to popup with data (like x, y values, maybe more).  Here is what I tried using:</p>
  
  <pre><code>vis.selectAll("circle")
     .data(datafiltered).enter().append("svg:circle")
     .attr("cx", function(d) { return x(d.x);})
     .attr("cy", function(d) {return y(d.y)})
     .attr("fill", "red").attr("r", 15)
     .on("mouseover", function() {
          d3.select(this).enter().append("text")
              .text(function(d) {return d.x;})
              .attr("x", function(d) {return x(d.x);})
              .attr("y", function (d) {return y(d.y);}); });
  </code></pre>
  
  <p>I suspect I need to be more informative about what data to enter?</p>