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Last active November 30, 2019 18:30
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Tree diagram with varying symbols for nodes
license: mit

This is an example of a tree digram where the nodes can be varied amongst the (range of symbols)[https://github.com/mbostock/d3/wiki/SVG-Shapes#symbol] available via the d3.svg.symbol command.

Many thanks to Josiah who asked the question of how this could be done.

There are of course several different methods. A separate custom svg path could be declared and used or a more elegant and extensible method might be to apply the symbol type depending on the range of input values (as is used in Mike Bostock's Force-directed Symbols.

It is used as an example and described in the book D3 Tips and Tricks.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Collapsible Tree Example</title>
<style>
.node circle {
fill: #fff;
stroke: steelblue;
stroke-width: 3px;
}
.node text { font: 12px sans-serif; }
.link {
fill: none;
stroke: #ccc;
stroke-width: 2px;
}
</style>
</head>
<body>
<!-- load the d3.js library -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<script>
var treeData = [
{
"name": "Top Level",
"parent": "null",
"value": 10,
"type": "black",
"level": "red",
"children": [
{
"name": "Level 2: A",
"parent": "Top Level",
"value": 5,
"type": "grey",
"level": "red",
"children": [
{
"name": "Son of A",
"parent": "Level 2: A",
"value": 5,
"type": "steelblue",
"level": "orange"
},
{
"name": "Daughter of A",
"parent": "Level 2: A",
"value": 18,
"type": "steelblue",
"level": "red"
}
]
},
{
"name": "Level 2: B",
"parent": "Top Level",
"value": 10,
"type": "grey",
"level": "green"
}
]
}
];
// ************** Generate the tree diagram *****************
var margin = {top: 20, right: 120, bottom: 20, left: 120},
width = 960 - margin.right - margin.left,
height = 500 - margin.top - margin.bottom;
var i = 0;
var tree = d3.layout.tree()
.size([height, width]);
var diagonal = d3.svg.diagonal()
.projection(function(d) { return [d.y, d.x]; });
var svg = d3.select("body").append("svg")
.attr("width", width + margin.right + margin.left)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
root = treeData[0];
update(root);
function update(source) {
// Compute the new tree layout.
var nodes = tree.nodes(root).reverse(),
links = tree.links(nodes);
// Normalize for fixed-depth.
nodes.forEach(function(d) { d.y = d.depth * 180; });
// Declare the nodes…
var node = svg.selectAll("g.node")
.data(nodes, function(d) { return d.id || (d.id = ++i); });
// Enter the nodes.
var nodeEnter = node.enter().append("g")
.attr("class", "node")
.attr("transform", function(d) {
return "translate(" + d.y + "," + d.x + ")"; });
nodeEnter.append("path")
.style("stroke", "black")
.style("fill", "white")
.attr("d", d3.svg.symbol()
.size(200)
.type(function(d) { if
(d.value >= 9) { return "cross"; } else if
(d.value <= 9) { return "diamond";}
}));
nodeEnter.append("text")
.attr("x", function(d) {
return d.children || d._children ?
(d.value + 4) * -1 : d.value + 4 })
.attr("dy", ".35em")
.attr("text-anchor", function(d) {
return d.children || d._children ? "end" : "start"; })
.text(function(d) { return d.name; })
.style("fill-opacity", 1);
// Declare the links…
var link = svg.selectAll("path.link")
.data(links, function(d) { return d.target.id; });
// Enter the links.
link.enter().insert("path", "g")
.attr("class", "link")
.style("stroke", function(d) { return d.target.level; })
.attr("d", diagonal);
}
</script>
</body>
</html>
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