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@tgk
Last active Apr 19, 2019
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Add and remove nodes

Click to add nodes! Nodes near the cursor will be linked to the new node. Clicking an existing node will remove it.

This is an extension of this example, adding the capability of removing nodes by clicking them. This means that dragging is no longer supported.

<!DOCTYPE html>
<meta charset="utf-8">
<style>
rect {
fill: none;
pointer-events: all;
}
.node {
fill: #000;
}
.cursor {
fill: none;
stroke: brown;
pointer-events: none;
}
.link {
stroke: #999;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500;
var fill = d3.scale.category20();
var force = d3.layout.force()
.size([width, height])
.nodes([{}]) // initialize with a single node
.linkDistance(30)
.charge(-60)
.on("tick", tick);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.on("mousemove", mousemove)
.on("mousedown", mousedownCanvas);
svg.append("rect")
.attr("width", width)
.attr("height", height);
var nodes = force.nodes(),
links = force.links(),
node = svg.selectAll(".node"),
link = svg.selectAll(".link");
var cursor = svg.append("circle")
.attr("r", 30)
.attr("transform", "translate(-100,-100)")
.attr("class", "cursor");
restart();
function mousemove() {
cursor.attr("transform", "translate(" + d3.mouse(this) + ")");
}
function mousedownCanvas() {
var point = d3.mouse(this),
node = {x: point[0], y: point[1]},
n = nodes.push(node);
// add links to any nearby nodes
nodes.forEach(function(target) {
var x = target.x - node.x,
y = target.y - node.y;
if (Math.sqrt(x * x + y * y) < 30) {
links.push({source: node, target: target});
}
});
restart();
}
function mousedownNode(d, i) {
nodes.splice(i, 1);
links = links.filter(function(l) {
return l.source !== d && l.target !== d;
});
d3.event.stopPropagation();
restart();
}
function tick() {
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; });
}
function restart() {
node = node.data(nodes);
node.enter().insert("circle", ".cursor")
.attr("class", "node")
.attr("r", 5)
.on("mousedown", mousedownNode);
node.exit()
.remove();
link = link.data(links);
link.enter().insert("line", ".node")
.attr("class", "link");
link.exit()
.remove();
force.start();
}
</script>
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