circle radius not updating on transition in d3 - d3.js

Question

I am having trouble with a transtion in d3. This jsfiddle illustrates the problem: http://jsfiddle.net/3bzsE/
When the page loads, dataset01 is used to create a circle for each person in the array. d.name is used as the key.
The blue rectangles below the chart are buttons that update the data on click.
Here is the update funciton:
function updateVis(data) {
var points = svg.selectAll('.nameinfo')
.data(data, function(d) { return d.name;});
var pointsEnter = points
.enter()
.append('g')
.attr('class', 'nameinfo');
pointsEnter
.append('circle')
.attr('cx', function(d) { return 10 + d.position * 100; })
.attr('cy', width/2)
.attr('r', 0)
.style('fill', function(d) { return z(d.position); })
.style('fill-opacity', 0.5)
.style('stroke', '#232323')
.append("title")
.text(function(d) { return d.name; });
pointsEnter
.append('text')
.attr('x', function(d) { return 10 + d.position * 100; })
.attr('y', width/2)
.attr("dy", "0.35em")
.style("text-anchor", "middle")
.style("font-size", "11px")
.text(function(d, i) { return d.name; });
pointsUpdate = points
.selectAll('circle')
.transition().duration(500)
.attr('r', function(d){ return d.value/2;});
var pointsExit = points.exit().transition().duration(500).remove();
pointsExit
.selectAll('circle')
.attr('r', 0);
}
The enter and exits are behaving as expected, but circle radius is not changing for names that are present in the entering and exiting datasets.
An example using the values for Jim:
clicking on button three with button one active:
Joe, Janet and Julie exit
Jane and John enter
But, the radius of Jim does not change (it should shrink because d.value changes from 130 to 50)
Clicking on two with three active causes Jim to exit. Clicking on three from two causes Jim to enter with the proper radius from dataset03.
The same behavior can be see with the other names. In all cases enters and exits work, but if two datasets have an element with the same name, radius is not updated on transition

Answer 1

You might have to specifically select the circles for your transition rather than trying to do it on the outer group element. So instead of this:
pointsUpdate = points
.selectAll('circle')
.transition().duration(500)
.attr('r', function(d){ return d.value/2;});
Do this:
svg.selectAll('.nameinfo circle')
.data(data, function(d) { return d.name;})
.transition().duration(500)
.attr('r', function(d){ return d.value/2;});
UPDATE: Below is another way that fits better with the overall D3 philosophy of reusing the existing data/selection:
points
.select('circle').transition().duration(500)
.attr('r', function(d){ return d.value/2;});