上記例の全コードは以下のようです
data_set = [ {name:"aaa"},
{name:"bbb"},
{name:"ccc"},
{name:"ddd"},
{name:"eee"},
{name:"fff"} ] ;
link_set = [
{source:"aaa", target:"bbb"},
{source:"bbb", target:"ccc"},
{source:"ccc", target:"ddd"},
{source:"ddd", target:"eee"},
{source:"eee", target:"fff"},
{source:"fff", target:"aaa"},
];
var width=600, height=300;
var force_g = d3.select("#content").append("g") ;
var links = force_g.selectAll(".link")
.data(link_set)
.enter()
.append("line")
.attr("class", "link")
.attr("stroke", "#000")
.attr("stroke-weight", 1)
;
var circles = force_g.selectAll("circle")
.data(data_set)
.enter()
.append("circle")
.attr("class","test-circle")
.attr("r", 5)
.attr("fill","lightblue")
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended)
)
;
var line_force = d3.forceSimulation()
.nodes(data_set)
.on("tick", ticked)
.force("link", d3.forceLink(link_set)
.id(function(d){ return d.name ; })
.distance(20) )
.force("center", d3.forceCenter(width/2, height/2))
.force('charge', d3.forceManyBody().strength(15))
.force("collision", d3.forceCollide(15))
;
function dragstarted(d) {
if (!d3.event.active) line_force.alphaTarget(0.9).restart();
d.fx = d.x;
d.fy = d.y;
}
function dragged(d) {
d.fx = d3.event.x;
d.fy = d3.event.y;
}
function dragended(d) {
if (!d3.event.active) line_force.alphaTarget(0);
d.fx = null;
d.fy = null;
}
function ticked(){
circles
.attr("cx", function(d){ return d.x; })
.attr("cy", function(d){ return d.y; }) ;
links
.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; });
}