How to place text on the circle when using D3.js force layout?

<!DOCTYPE html>
<html>
<meta charset="utf-8">

<style>

.node {
  stroke: #fff;
  stroke-width: 1.5px;
}

.link {
  stroke: #999;
  stroke-opacity: .6;
}

</style>
<body>
</body>
<script src="d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
    .charge(-120)
    .linkDistance(30)
    .size([width, height]);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

d3.json("data.json", function(error, graph) {
  force
      .nodes(graph.nodes)
      .links(graph.links)
      .start();

  var link = svg.selectAll(".link")
      .data(graph.links)
    .enter().append("line")
      .attr("class", "link")
      .style("stroke-width", function(d) { return Math.sqrt(d.value); });

  var node = svg.selectAll(".node")
      .data(graph.nodes)
    .enter().append("circle")
      .attr("class", "node")
      .attr("r", function(d) {return d.r;})
      .style("fill", function(d) { return color(d.group); })

  node.append("title")
      .text(function(d) { return d.name; });

  node.append("text")
       .text("A");

  force.on("tick", function() {
    link.attr("x1", function(d) { return d.source.x; })
        .attr("y1", function(d) { return d.source.y; })
        .attr("x2", function(d) { return d.target.x; })
        .attr("y2", function(d) { return d.target.y; });

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

</script>
</html>

The code above is using D3js to draw a Force-directed graph drawing from some data, and I just want to place some text on the circle so I use node.append("text") you can see it above.

But however when add it it does not work, there is still not text on the circle so I wonder how could it be????

SVG does not allow a text element inside an circle element. You should put the circle and the text element inside a common g. Try something like this (not tested):

  var node = svg.selectAll(".node")
      .data(graph.nodes).enter().append('g').classed('node', true);

  node.append("circle")
      .attr("r", function(d) {return d.r;})
      .style("fill", function(d) { return color(d.group); })
      .append("title")
      .text(function(d) { return d.name; });

  node.append("text")
       .text("A");

And then instead of setting cx and cy on nodes, set the transform property on the g.node:

  force.on("tick", function() {
    // ...

    node.attr("transform", function(d) { return 'translate(' + [d.x, d.y] + ')'; })
  });

来源：https://stackoverflow.com/questions/20662192/how-to-place-text-on-the-circle-when-using-d3-js-force-layout

标签

javascript

d3.js

force-layout