Question

I’m using one of the force layout examples (http://bl.ocks.org/1153292) to show a network on my web site.

I allow the user to choose which type of links to see at any given time. I notice that when I choose to see link type A, then add link type B and then remove link type A the remain links of type B are presented with A colors.

This is the code that runs to add the links to the svg diagram. I am changing the array this.links by adding and removing links from it. As you can see I set the class attribute but it is not updating – it remains of type of link A.

var path = svg.append("svg:g")
    .selectAll("path")
    .data(this.links)
   .enter()
    .append("svg:path")
    .attr("class", function(d) { return "link " + d.type; })
    .attr("marker-end", function(d) { return "url(#" + d.type + ")"; });

I currently work around this problem by updating the class attribute inside the tick function but this off course cause much un-needed work.

I read that the enter operation return a merged selection of the exist elements and also the new ones so the attr operation should update the exist one and set the new one.

What am I missing?

Answer 1

I’ve found the answer in this post

var circle = svg.selectAll("circle")
    .data(data);

circle.enter().append("circle")
    .attr("r", 2.5);

circle
    .attr("cx", function(d) { return d.x; })
    .attr("cy", function(d) { return d.y; });

circle.exit().remove();

The answer is that I need to call attr operator on the result of selectAll.data and not on the result of the append operator.