I have developed a force layout to represent relationships between social groups. Now I would like to get the nodes to be distributed in a circle with links joining them. What is the best way to do this?
The complete version of the code (without data) is here http://jsfiddle.net/PatriciaW/zZSJT/ (Why do I have to include code here too? Here is the main portion)
d3.json("/relationships?nocache=" + (new Date()).getTime(),function(error,members){
var links=members.organizations.map(function(members) {
return members.member;
});
var nodes = {};
links.forEach(function(link) {
link.source = nodes[link.xsource] || (nodes[link.xsource] = {source: link.xsource, name: link.xsource, category: link.categorysource, path: link.pathsource, desc: link.descsource, title: link.titlesource});
link.target = nodes[link.xtarget] || (nodes[link.xtarget] = {target: link.xtarget, name: link.xtarget, category: link.categorytarget, path: link.pathtarget, desc: link.desctarget, title: link.titletarget});
});
force = d3.layout.force()
.nodes(d3.values(nodes))
.links(links)
.size([width, height])
.charge(-120)
.linkDistance(function() {return (Math.random() * 200) + 100;})
.linkStrength(0.5)
.on("tick", tick)
.start();
var link = svg.selectAll(".link")
.data(force.links())
.enter().append("line")
.attr("class", "link");
var node_drag = d3.behavior.drag()
.on("dragstart", dragstart)
.on("drag", dragmove)
.on("dragend", dragend);
var loading = svg.append("text")
.attr("x", width / 2)
.attr("y", height / 2)
.attr("dy", ".35em")
.style("text-anchor", "middle")
.text("Simulating. One moment please…");
function dragstart(d, i) {
force.stop() // stops the force auto positioning before you start dragging
}
function dragmove(d, i) {
d.px += d3.event.dx;
d.py += d3.event.dy;
d.x += d3.event.dx;
d.y += d3.event.dy;
tick(); // this is the key to make it work together with updating both px,py,x,y on d !
}
function dragend(d, i) {
d.fixed = true; // of course set the node to fixed so the force doesn't include the node in its auto positioning stuff
tick();
force.resume();
};
var node = svg.selectAll(".node")
.data(force.nodes())
.enter().append("g")
.attr("class", "node")
.on("mouseover", mouseover)
.on("mouseout", mouseout)
.on("click", clickAlert)
.call(node_drag);
node.append("circle")
.attr("r", 8)
.style("fill", function(d) {
return categoryColour [d.category];
})
// add an image marker
node.append("image")
.attr("x",-8)
.attr("y",-8)
.attr("width", 16)
.attr("height", 16)
.attr("xlink:href", function(d) {
return categoryImage [d.category]
})
.on("click", clickAlert)
.style("cursor", "pointer")
node.append("text")
.attr("x", 12)
.attr("dy", ".35em")
.text(function(d) {
return d.name;
});
// Use a timeout to allow the rest of the page to load first.
setTimeout(function() {
// Run the layout a fixed number of times.
// The ideal number of times scales with graph complexity.
force.start();
for (var i = n * n; i > 0; --i) force.tick();
force.stop();
svg.selectAll("line")
.data(links)
.enter().append("line")
.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; });
svg.selectAll("circle")
.data(nodes)
.enter().append("circle")
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", 4.5);
loading.remove();
}, 10);
function tick() {
link
.attr("x1", function(d) {
return d.source.x + xadj; })
.attr("y1", function(d) {
return d.source.y + yadj; })
.attr("x2", function(d) {
return d.target.x +xadj; })
.attr("y2", function(d) {
return d.target.y +yadj; });
node
.attr("transform", function(d) {
return "translate(" + (d.x + xadj) + "," + (d.y + yadj) + ")";
});
};
function mouseover() {
d3.select(this).select("circle").transition()
.duration(750)
.attr("r", 16);
d3.select(this).select("text")
.attr("font-size","34px")
.style("font-weight", "bold");
};
function mouseout() {
d3.select(this).select("circle").transition()
.duration(750)
.attr("r", 8);
d3.select(this).select("text")
.attr("font-size","12px")
.style("font-weight", "normal");
};
}) // end json
Here's someone else's solution:
This network graph uses the D3 force layout to draw nodes and links, but instead of using d3.force() to find the best node positions, we draw an invisible arc and evenly places nodes along the circumference.
<!DOCTYPE html>
<html>
<head>
<script src="http://d3js.org/d3.v3.min.js"></script>
<meta charset="utf-8">
<title>JS Bin</title>
<style>
line.node-link, path.node-link {
fill: none;
stroke: black
}
circle.node {
fill: white;
stroke: black
}
circle.node+text {
text-anchor: middle;
}
text {
font-family: sans-serif;
pointer-events: none;
}
</style>
</head>
<body>
<script type="text/javascript">
// number of random nodes (gets crowded at >25 unless you change node diameter)
var num = 20;
// returns random int between 0 and num
function getRandomInt() {return Math.floor(Math.random() * (num));}
// nodes returns a [list] of {id: 1, fixed:true}
var nodes = d3.range(num).map(function(d) { return {id: d}; });
// links returns a [list] of {source: 0, target: 1} (values refer to indicies of nodes)
var links = d3.range(num).map(function(d) { return {source: getRandomInt(), target: getRandomInt()}; });
var width = 500,
height = 500;
var force = d3.layout.force()
.nodes(nodes)
.links(links)
.size([width, height]);
// evenly spaces nodes along arc
var circleCoord = function(node, index, num_nodes){
var circumference = circle.node().getTotalLength();
var pointAtLength = function(l){return circle.node().getPointAtLength(l)};
var sectionLength = (circumference)/num_nodes;
var position = sectionLength*index+sectionLength/2;
return pointAtLength(circumference-position)
}
// fades out lines that aren't connected to node d
var is_connected = function(d, opacity) {
lines.transition().style("stroke-opacity", function(o) {
return o.source === d || o.target === d ? 1 : opacity;
});
}
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
// invisible circle for placing nodes
// it's actually two arcs so we can use the getPointAtLength() and getTotalLength() methods
var dim = width-80
var circle = svg.append("path")
.attr("d", "M 40, "+(dim/2+40)+" a "+dim/2+","+dim/2+" 0 1,0 "+dim+",0 a "+dim/2+","+dim/2+" 0 1,0 "+dim*-1+",0")
.style("fill", "#f5f5f5");
force.start();
// set coordinates for container nodes
nodes.forEach(function(n, i) {
var coord = circleCoord(n, i, nodes.length)
n.x = coord.x
n.y = coord.y
});
// use this one for straight line links...
// var lines = svg.selectAll("line.node-link")
// .data(links).enter().append("line")
// .attr("class", "node-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; });
// ...or use this one for curved line links
var lines = svg.selectAll("path.node-link")
.data(links).enter().append("path")
.attr("class", "node-link")
.attr("d", function(d) {
var dx = d.target.x - d.source.x,
dy = d.target.y - d.source.y,
dr = Math.sqrt(dx * dx + dy * dy);
return "M" +
d.source.x + "," +
d.source.y + "A" +
dr + "," + dr + " 0 0,1 " +
d.target.x + "," +
d.target.y;
});
var gnodes = svg.selectAll('g.gnode')
.data(nodes).enter().append('g')
.attr("transform", function(d) {
return "translate("+d.x+","+d.y+")"
})
.classed('gnode', true);
var node = gnodes.append("circle")
.attr("r", 25)
.attr("class", "node")
.on("mouseenter", function(d) {
is_connected(d, 0.1)
node.transition().duration(100).attr("r", 25)
d3.select(this).transition().duration(100).attr("r", 30)
})
.on("mouseleave", function(d) {
node.transition().duration(100).attr("r", 25);
is_connected(d, 1);
});
var labels = gnodes.append("text")
.attr("dy", 4)
.text(function(d){return d.id})
</script>
</body>
</html>
来源：https://stackoverflow.com/questions/22439832/d3-js-how-do-i-arrange-nodes-of-a-force-layout-to-be-on-a-circle