问题
I am working on web crawler visualization using D3 that uses a forced-based labeled graph like the one shown here: Force-based label placement graph
I am unable to get two parent nodes to have the same common child. Is this not possible using this graph? Because the example case shows such a scenario where two nodes share the same child. How do I do this? I am using the following script on my webpage to populate and show the graph (The array being shown in the script is just a dummy array I am using for testing, but the structure of the object resembles to the actual data that will be handled). Please help!
Note: This code works just fine if I make sure that no node has multiple parent nodes. Edit: The .category property being used in available in the original QueuedORG array, I have not used it in the sample QueuedORG array I am creating in the script. It's not important as yet.
document.addEventListener('DOMContentLoaded', function () {
drawVisual();
});
function drawVisual()
{
var w = 960, h = 500;
//var w = 1024, h = 768;
//var vis = d3.select("#tab_5_contents").append("svg:svg").attr("width", w).attr("height", h);
var vis = d3.select("#forcedLayoutGraph").append("svg:svg").attr("width", w).attr("height", h);
var QueuedORG = [];
//QueuedORG = JSON.parse(localStorage.getItem('storeArray'));
QueuedORG.push({url: "Root", parentURL: "Root", used:0});
QueuedORG.push({url: "a", parentURL: "Root"});
QueuedORG.push({url: "b", parentURL: "Root"});
QueuedORG.push({url: "c", parentURL: "Root"});
QueuedORG.push({url: "d", parentURL: "Root"});
QueuedORG.push({url: "e", parentURL: "a"});
QueuedORG.push({url: "f", parentURL: "a"});
QueuedORG.push({url: "g", parentURL: "a"});
QueuedORG.push({url: "h", parentURL: "a"});
QueuedORG.push({url: "p", parentURL: "b"});
QueuedORG.push({url: "q", parentURL: "b"});
QueuedORG.push({url: "r", parentURL: "b"});
QueuedORG.push({url: "x", parentURL: "c"});
QueuedORG.push({url: "y", parentURL: "x"});
QueuedORG.push({url: "y", parentURL: "c"});
QueuedORG.push({url: "x", parentURL: "a"});
QueuedORG.push({url: "y", parentURL: "b"});
var nodes = [];
var labelAnchors = [];
var labelAnchorLinks = [];
var links = [];
for(var i = 0; i < QueuedORG.length; i++)
{
var nodeExists = 0;
//check to see if a node for the current url has already been created. If yes, do not create a new node
for(var j = 0; j < nodes.length; j++)
{
if(QueuedORG[i].url == nodes[j].label)
nodeExists = 1;
}
if (nodeExists == 0)
{
var urlLabel = QueuedORG[i].url;
//remove 'http://' part
/*urlLabel = urlLabel.split("http://")[1];
if(urlLabel.match("www"))
urlLabel = urlLabel.split("www.")[1];
var rest = urlLabel.split("\.")[1];
urlLabel = urlLabel.split("\.")[0];*/
var node = {
label : QueuedORG[i].url,
category : QueuedORG[i].category
};
nodes.push(node);
labelAnchors.push({
node : node
});
labelAnchors.push({
node : node
});
}
};
for(var i=0;i<nodes.length; i++)
{
console.log("node i:"+i+nodes[i]+"\n");
console.log("labelAnchor i:"+i+labelAnchors[i]+"\n");
}
//To create links for connecting nodes
for(var i = 0; i < QueuedORG.length; i++)
{
var srcIndx = 0, tgtIndx = 0;
for(var j = 0; j < nodes.length; j++)
{
if( QueuedORG[i].url == nodes[j].label ) //to find the node number for the current url
{
srcIndx = j;
}
if( QueuedORG[i].parentURL == nodes[j].label ) //to find the node number for the parent url
{
tgtIndx = j;
}
}
//console.log("src:"+srcIndx+" tgt:"+tgtIndx);
//connecting the current url's node to the parent url's node
links.push({
source : srcIndx,
target : tgtIndx,
weight : 1,
});
labelAnchorLinks.push({
source : i * 2,
target : i * 2 + 1,
weight : 1
});
};
var force = d3.layout.force().size([w, h]).nodes(nodes).links(links).gravity(1).charge(-10000).linkStrength(function(x) {
return x.weight * 10 // charge is for inter-node repel, link distance is node-node distance
});
force.linkDistance(function(d) {
return d.weight * 100;
});
force.start();
var force2 = d3.layout.force().nodes(labelAnchors).links(labelAnchorLinks).gravity(0).linkStrength(10).charge(-500).size([w, h]); //charge is for inter-label repel, link distance is node-label distance
force2.linkDistance(function(d) {
return d.weight * 10;
});
force2.start();
var link = vis.selectAll("line.link").data(links).enter().append("svg:line").attr("class", "link").style("stroke", "#CCC");
var colors = {"1": "black", "2": "blue", "3": "red"}; // 1=root node 2=blog nodes 3=.org nodes
var shape = {"1": "diamond", "2": "cross", "3": "circle"};
var node = vis.selectAll("g.node").data(force.nodes()).enter().append("path").attr("class", "node").call(force.drag);
//node.append("circle").attr("r", 5).style("stroke", "#FFF").style("stroke-width", 3).attr("class", function(d) {return "node category"+d.category});
node.attr("d", d3.svg.symbol().type(function(d) {return shape[d.category];})).style("stroke", "#FFF").style("fill", function(d){ return colors[d.category];});
var anchorLink = vis.selectAll("line.anchorLink").data(labelAnchorLinks)//.enter().append("svg:line").attr("class", "anchorLink").style("stroke", "#999");
var anchorNode = vis.selectAll("g.anchorNode").data(force2.nodes()).enter().append("svg:g").attr("class", "anchorNode");
anchorNode.append("svg:circle").attr("r", 0).style("fill", "#FFF");
anchorNode.append("svg:text").text(function(d, i) {
return i % 2 == 0 ? "" : d.node.label
}).style("fill", "#555").style("font-family", "Arial").style("font-size", 12);
var updateLink = function() {
this.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;
});
}
var updateNode = function() {
this.attr("transform", function(d) {
return "translate(" + d.x + "," + d.y + ")";
});
}
force.on("tick", function() {
force2.start();
node.call(updateNode);
anchorNode.each(function(d, i) {
if(i % 2 == 0) {
d.x = d.node.x;
d.y = d.node.y;
} else {
var b = this.childNodes[1].getBBox();
var diffX = d.x - d.node.x;
var diffY = d.y - d.node.y;
var dist = Math.sqrt(diffX * diffX + diffY * diffY);
var shiftX = b.width * (diffX - dist) / (dist * 2);
shiftX = Math.max(-b.width, Math.min(0, shiftX));
var shiftY = 5;
this.childNodes[1].setAttribute("transform", "translate(" + shiftX + "," + shiftY + ")");
}
});
anchorNode.call(updateNode);
link.call(updateLink);
anchorLink.call(updateLink);
});
}
回答1:
The problem is the way you assemble your labelAnchorLinks. By using indices i*2 and i*2+1, you're assuming that there's two nodes for each i. This will only be true if everything in QueuedORG denotes a new node.
To fix, use the index of the source node instead of i:
labelAnchorLinks.push({
source : srcIndex * 2,
target : srcIndex * 2 + 1,
weight : 1
});
来源：https://stackoverflow.com/questions/20525458/how-to-get-common-child-node-in-d3-js-force-based-labeled-layout-graph