display axes in a circle with equal spacing in between - d3.js

As you can see from this example by Mike Bostock, it is possible to display the axis to a graph in a circle. In the linked to example, there are three axis (with the areas in between of equal size) which seemed to be created by this line of code
var angle = d3.scale.ordinal().domain(d3.range(4)).rangePoints([0, 2 * Math.PI]),
plus
svg.selectAll(".axis")
.data(d3.range(3))
.enter().append("line")
.attr("class", "axis")
.attr("transform", function(d) { return "rotate(" + degrees(angle(d)) + ")"; })
.attr("x1", radius.range()[0])
.attr("x2", radius.range()[1]);
Playing around with that example, I was able to create a graph with six axes (with equal spacing between each axis) that covered the whole circle using this code
var angle = d3.scale.ordinal().domain(["one", "two", "three", "four", "five", "six"]).range([0, 45, 90, 135, 180, 225])
and then
svg.selectAll(".axis").data(d3.range(7))
//code omitted
However, I haven't been able to create a circle with 9 axes (with equal spacing in between) by doing this (as I expected it would)
var angle = d3.scale.ordinal()
.domain(["one", "two", "three", "four", "five", "six", "seven", "eight", "nine"])
.range([0, 45, 90, 135, 180, 225, 270, 315, 360]);
svg.selectAll(".axis").data(d3.range(10))
//code omitted
The result of doing this is that the axes start to go around the circle a second time.
Question: is there a pattern that can be followed to have an arbitrary number of axes displayed in a circle with equal spacing in between each? If so, please explain the d3 principles behind the two successful attempts and the one unsuccessful attempt shown and linked to above.
Update
Although removing the calls to degrees, puts the axes in the right position, (and then removing the call to degrees in the nodes code puts the nodes on the axes in the right axes), the links are not lining up properly i.e. they are not starting and ending on the axes, but rather floating unanchored. You can see the problem in this image
This is the code for the links (notice that it doesn't have a call to degrees)
svg.selectAll(".link")
.data(linx)
.enter().append("path")
.attr("class", "link")
.attr("class", function(d) { return "link " + d.Class})
.attr("d", link()
.angle(function(d) { return angle(d.X); })
.radius(function(d) { return radius(d.Y); }))
.on("mouseover", linkMouseover)
.on("mouseout", mouseout);
It calls a link function (which also doens't have a call to degrees, so I don't know why the links are starting and ending at the old position of the axes) that I got from Mike Bostock's hive implementation
function link() {
var source = function(d) { return d.Source; },
target = function(d) { return d.Target; },
angle = function(d) { return d.angle; },
startRadius = function(d) { return d.radius; },
endRadius = startRadius,
arcOffset = -Math.PI / 2;
function link(d, i) {
// console.log(d, i, "interior link func");
var s = node(source, this, d, i),
t = node(target, this, d, i),
x;
if (t.a < s.a) x = t, t = s, s = x;
if (t.a - s.a > Math.PI) s.a += 2 * Math.PI;
var a1 = s.a + (t.a - s.a) / 3,
a2 = t.a - (t.a - s.a) / 3;
return s.r0 - s.r1 || t.r0 - t.r1
? "M" + Math.cos(s.a) * s.r0 + "," + Math.sin(s.a) * s.r0
+ "L" + Math.cos(s.a) * s.r1 + "," + Math.sin(s.a) * s.r1
+ "C" + Math.cos(a1) * s.r1 + "," + Math.sin(a1) * s.r1
+ " " + Math.cos(a2) * t.r1 + "," + Math.sin(a2) * t.r1
+ " " + Math.cos(t.a) * t.r1 + "," + Math.sin(t.a) * t.r1
+ "L" + Math.cos(t.a) * t.r0 + "," + Math.sin(t.a) * t.r0
+ "C" + Math.cos(a2) * t.r0 + "," + Math.sin(a2) * t.r0
+ " " + Math.cos(a1) * s.r0 + "," + Math.sin(a1) * s.r0
+ " " + Math.cos(s.a) * s.r0 + "," + Math.sin(s.a) * s.r0
: "M" + Math.cos(s.a) * s.r0 + "," + Math.sin(s.a) * s.r0
+ "C" + Math.cos(a1) * s.r1 + "," + Math.sin(a1) * s.r1
+ " " + Math.cos(a2) * t.r1 + "," + Math.sin(a2) * t.r1
+ " " + Math.cos(t.a) * t.r1 + "," + Math.sin(t.a) * t.r1;
}
function node(method, thiz, d, i) {
var node = method.call(thiz, d, i),
a = +(typeof angle === "function" ? angle.call(thiz, node, i) : angle) + arcOffset,
r0 = +(typeof startRadius === "function" ? startRadius.call(thiz, node, i) : startRadius),
r1 = (startRadius === endRadius ? r0 : +(typeof endRadius === "function" ? endRadius.call(thiz, node, i) : endRadius));
return {r0: r0, r1: r1, a: a};
}
link.source = function(_) {
if (!arguments.length) return source;
source = _;
return link;
};
link.target = function(_) {
if (!arguments.length) return target;
target = _;
return link;
};
link.angle = function(_) {
if (!arguments.length) return angle;
angle = _;
return link;
};
link.radius = function(_) {
if (!arguments.length) return startRadius;
startRadius = endRadius = _;
return link;
};
link.startRadius = function(_) {
if (!arguments.length) return startRadius;
startRadius = _;
return link;
};
link.endRadius = function(_) {
if (!arguments.length) return endRadius;
endRadius = _;
return link;
};
return link;
}

You have angles in degrees already, you don't need to use the degree() function. If you remove the call to that everything will work fine.

Related

Existing Triangles Cannot be Removed

I bind triangles with data in D3.js. But the triganle cannot be removed with the data. The rectangles are okay. Complete code is attached!
var svg = d3.select("body").append("svg")
.attr("width", 250)
.attr("height", 250);
function render(data){
var tris = svg.selectAll("tri").data(data);
tris.enter().append("path");
tris.attr("d", function(d) {
var x1 = (0.4 - 0.2 * (d - 1)) * 250, y1 = 0.3 * 250;
var x2 = (0.5 - 0.2 * (d - 1)) * 250, y2 = 0.1 * 250;
var x3 = (0.6 - 0.2 * (d - 1)) * 250, y3 = 0.3 * 250;
return "M" + x1 + " " + y1 + " L" + x2 + " " + y2 + " L" + x3 + " " + y3 + "Z";
});
tris.exit().remove();
var rects = svg.selectAll("rect").data(data);
rects.enter().append("rect");
rects.attr("y", 50)
.attr("width", 20)
.attr("height", 20)
.attr("x", function(d) { return d * 40; });
rects.exit().remove();
}
render([1, 2, 3]);
render([1, 2]);
render([1]);
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
There is no SVG element called <tri>. Your enter selection works because you can select anything in your data binding function. As there is nothing named "tri" in the whole DOM (be it a tag, a class, an ID, whatever...), your enter selection is never empty and your exit selection is never populated.
That being said, an easy solution is selecting by class...
var tris = svg.selectAll(".tri").data(data);
And setting this class in your enter selection:
tris.enter().append("path").attr("class", "tri");
Here is your code with the changes:
var svg = d3.select("body").append("svg")
.attr("width", 250)
.attr("height", 250);
function render(data){
var tris = svg.selectAll(".tri").data(data);
tris.enter().append("path").attr("class","tri");
tris.attr("d", function(d) {
var x1 = (0.4 - 0.2 * (d - 1)) * 250, y1 = 0.3 * 250;
var x2 = (0.5 - 0.2 * (d - 1)) * 250, y2 = 0.1 * 250;
var x3 = (0.6 - 0.2 * (d - 1)) * 250, y3 = 0.3 * 250;
return "M" + x1 + " " + y1 + " L" + x2 + " " + y2 + " L" + x3 + " " + y3 + "Z";
});
tris.exit().remove();
var rects = svg.selectAll("rect").data(data);
rects.enter().append("rect");
rects.attr("y", 50)
.attr("width", 20)
.attr("height", 20)
.attr("x", function(d) { return d * 40; });
rects.exit().remove();
}
render([1, 2, 3]);
setTimeout(() => render([1, 2]), 1000);
setTimeout(() => render([1]), 2000)
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

Specifying a number of nodes in each cluster of clustered force layout in d3js

I am trying to design an infographic using the Clustered Force Layout III example and I have it almost the way I want, but I need to specify a number of nodes per cluster. Cluster 1 - 10 nodes, Cluster 2 - 7 nodes, Cluster 3 - 11 nodes, Cluster 4 - 18 nodes, Cluster 5 - 16 nodes, Cluster 6 - 19 nodes, Cluster 7 - 42 nodes, Cluster 8 - 14 nodes. I have the correct total number of nodes and the correct total number of Clusters and I've made all the nodes the same size. Now I just need to push the circles around to represent by data. My code is below.
var width = 175,
height = 175,
padding = 1.5, // separation between same-color nodes
clusterPadding = 6, // separation between different-color nodes
maxRadius = 4;
var n = 137, // total number of nodes
m = 8; // number of distinct clusters
var color = d3.scale.category10()
.domain(d3.range(m));
// The largest node for each cluster.
var clusters = new Array(m);
var nodes = d3.range(n).map(function() {
var i = Math.floor(Math.random() * m),
r = maxRadius,
d = {
cluster: i,
radius: r,
x: Math.cos(i / m * 2 * Math.PI) * 200 + width / 2 + Math.random(),
y: Math.sin(i / m * 2 * Math.PI) * 200 + height / 2 + Math.random()
};
if (!clusters[i] || (r > clusters[i].radius)) clusters[i] = d;
return d;
});
var force = d3.layout.force()
.nodes(nodes)
.size([width, height])
.gravity(.02)
.charge(0)
.on("tick", tick)
.start();
var svg = d3.select(".wpd3-1042-0").append("svg")
.attr("width", width)
.attr("height", height);
var node = svg.selectAll("circle")
.data(nodes)
.enter().append("circle")
.style("fill", function(d) { return color(d.cluster); })
.call(force.drag);
node.transition()
.duration(750)
.delay(function(d, i) { return i * 5; })
.attrTween("r", function(d) {
var i = d3.interpolate(0, d.radius);
return function(t) { return d.radius = i(t); };
});
function tick(e) {
node
.each(cluster(10 * e.alpha * e.alpha))
.each(collide(.5))
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
}
// Move d to be adjacent to the cluster node.
function cluster(alpha) {
return function(d) {
var cluster = clusters[d.cluster];
if (cluster === d) return;
var x = d.x - cluster.x,
y = d.y - cluster.y,
l = Math.sqrt(x * x + y * y),
r = d.radius + cluster.radius;
if (l != r) {
l = (l - r) / l * alpha;
d.x -= x *= l;
d.y -= y *= l;
cluster.x += x;
cluster.y += y;
}
};
}
// Resolves collisions between d and all other circles.
function collide(alpha) {
var quadtree = d3.geom.quadtree(nodes);
return function(d) {
var r = d.radius + maxRadius + Math.max(padding, clusterPadding),
nx1 = d.x - r,
nx2 = d.x + r,
ny1 = d.y - r,
ny2 = d.y + r;
quadtree.visit(function(quad, x1, y1, x2, y2) {
if (quad.point && (quad.point !== d)) {
var x = d.x - quad.point.x,
y = d.y - quad.point.y,
l = Math.sqrt(x * x + y * y),
r = d.radius + quad.point.radius + (d.cluster === quad.point.cluster ? padding : clusterPadding);
if (l < r) {
l = (l - r) / l * alpha;
d.x -= x *= l;
d.y -= y *= l;
quad.point.x += x;
quad.point.y += y;
}
}
return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
});
};
}
Yes! you can achieve this by doing something like this:
var clusterNumber = [10, 7, 11, 18, 16, 19, 42, 14];//your cluster number of node array
var n = d3.sum(clusterNumber, function (d) {
return d
}); /// total number of nodes
var m = clusterNumber.length;//total number of clusters
var color = d3.scale.category10()
.domain(d3.range(m));
// The largest node for each cluster.
var clusters = new Array(m);
var nodes = [];
clusterNumber.forEach(function (cn, i) {
//this will make a cluster
var r = maxRadius;
for (var j = 0; j < cn; j++) {
//this loop will make all the nodes
var d = {
cluster: i,
radius: r,
x: Math.cos(i / m * 2 * Math.PI) * 200 + width / 2 + Math.random(),
y: Math.sin(i / m * 2 * Math.PI) * 200 + height / 2 + Math.random()
};
if (!clusters[i] || (r > clusters[i].radius)) clusters[i] = d;
nodes.push(d);
}
});
Full working code here
Hope this helps!

Can one specify a custom force function for a force-directed layout?

I want to experiment with an alternative family force functions for force-directed graph layouts.
For each node n_i, I can define a "force function" f_i such that
f_i ( n_i ) is identically zero; and
f_i ( n_j ), where n_i != n_j, is the force on node n_i that is due to some other node n_j.
The net force on node n_i should then be the vector sum of the forces f_i ( n_j ), where n_j ranges over all other nodes1.
Is there some way to tell d3.js to use these custom force functions in the layout algorithm?
[The documentation for d3.js's force-directed layout describes various ways in which its built-in force function can be tweaked, but I have not been able to find a way to specify an entirely different force function altogether, i.e. a force function that cannot be achieved by tweaking the parameters of the built-in force function.]
1IOW, no other/additional forces should act on node n_i besides those computed from its force function f_i.
Yes you can. Credit goes to Shan Carter and his bl.ocks example
let margin = {
top: 100,
right: 100,
bottom: 100,
left: 100
};
let width = 960,
height = 500,
padding = 1.5, // separation between same-color circles
clusterPadding = 6, // separation between different-color circles
maxRadius = 12;
let n = 200, // total number of nodes
m = 10, // number of distinct clusters
z = d3.scaleOrdinal(d3.schemeCategory20),
clusters = new Array(m);
let svg = d3.select('body')
.append('svg')
.attr('height', height)
.attr('width', width)
.append('g').attr('transform', 'translate(' + width / 2 + ',' + height / 2 + ')');
let nodes = d3.range(200).map(() => {
let i = Math.floor(Math.random() * m),
radius = Math.sqrt((i + 1) / m * -Math.log(Math.random())) * maxRadius,
d = {
cluster: i,
r: radius
};
if (!clusters[i] || (radius > clusters[i].r)) clusters[i] = d;
return d;
});
let circles = svg.append('g')
.datum(nodes)
.selectAll('.circle')
.data(d => d)
.enter().append('circle')
.attr('r', (d) => d.r)
.attr('fill', (d) => z(d.cluster))
.attr('stroke', 'black')
.attr('stroke-width', 1);
let simulation = d3.forceSimulation(nodes)
.velocityDecay(0.2)
.force("x", d3.forceX().strength(.0005))
.force("y", d3.forceY().strength(.0005))
.force("collide", collide) // <<-------- CUSTOM FORCE
.force("cluster", clustering)//<<------- CUSTOM FORCE
.on("tick", ticked);
function ticked() {
circles
.attr('cx', (d) => d.x)
.attr('cy', (d) => d.y);
}
// Custom 'clustering' force implementation.
function clustering(alpha) {
nodes.forEach(function(d) {
var cluster = clusters[d.cluster];
if (cluster === d) return;
var x = d.x - cluster.x,
y = d.y - cluster.y,
l = Math.sqrt(x * x + y * y),
r = d.r + cluster.r;
if (l !== r) {
l = (l - r) / l * alpha;
d.x -= x *= l;
d.y -= y *= l;
cluster.x += x;
cluster.y += y;
}
});
}
// Custom 'collide' force implementation.
function collide(alpha) {
var quadtree = d3.quadtree()
.x((d) => d.x)
.y((d) => d.y)
.addAll(nodes);
nodes.forEach(function(d) {
var r = d.r + maxRadius + Math.max(padding, clusterPadding),
nx1 = d.x - r,
nx2 = d.x + r,
ny1 = d.y - r,
ny2 = d.y + r;
quadtree.visit(function(quad, x1, y1, x2, y2) {
if (quad.data && (quad.data !== d)) {
var x = d.x - quad.data.x,
y = d.y - quad.data.y,
l = Math.sqrt(x * x + y * y),
r = d.r + quad.data.r + (d.cluster === quad.data.cluster ? padding : clusterPadding);
if (l < r) {
l = (l - r) / l * alpha;
d.x -= x *= l;
d.y -= y *= l;
quad.data.x += x;
quad.data.y += y;
}
}
return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
});
});
}
<!doctype html>
<meta charset="utf-8">
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
Also here is a more in-depth look at the subject.
To achieve this, you'll need to create your own custom layout. There's no tutorial for this that I'm aware of, but the source code for the existing force layout should be a good starting point as, by the sound of it, the structure of your custom layout would be very similar to that.

arrows on links in d3js force layout

I'm using the force layout to represent a directed unweighted network. My inspiration comes from the following example: http://bl.ocks.org/mbostock/1153292
I tried to make nodes of different sizes, but I have a little problem.
The marker used to draw the arrow on each link points to the center of the circle. If the circle is too big it covers completely the arrow.
How can I handle this?
If you will use a <line> instead of <path>, the following should work for you, I have it working in my current solution. It's based on #ɭɘ ɖɵʊɒɼɖ 江戸 solution:
In your tick event listener:
linkElements.attr("x1", function(d) { return d.source.x; })
.attr("y1", function(d) { return d.source.y; })
.attr("x2", function(d) {
return getTargetNodeCircumferencePoint(d)[0];
})
.attr("y2", function(d) {
return getTargetNodeCircumferencePoint(d)[1];
});
function getTargetNodeCircumferencePoint(d){
var t_radius = d.target.nodeWidth/2; // nodeWidth is just a custom attribute I calculate during the creation of the nodes depending on the node width
var dx = d.target.x - d.source.x;
var dy = d.target.y - d.source.y;
var gamma = Math.atan2(dy,dx); // Math.atan2 returns the angle in the correct quadrant as opposed to Math.atan
var tx = d.target.x - (Math.cos(gamma) * t_radius);
var ty = d.target.y - (Math.sin(gamma) * t_radius);
return [tx,ty];
}
I am sure this solution can be modified to accomodate <path> elements, however I haven't tried it.
You can offset the target of the link by the radius of the node, i.e. adjust the code
path.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;
});
by changing the values of d.target.x and d.target.y to take the radius (which would need to be part of the data, something like d.target.radius) into account. That is, offset the end of the arrow by the circle radius.
At the end I've decided to create a marker for each link (instead of one per class).
This solution has the advantage of defining the offset of each marker, depending on the target node which, in my own case, is refX.
// One marker for link...
svg.append("svg:defs").selectAll("marker")
.data(force.links())
.enter().append("svg:marker")
.attr("id", function(link, idx){ return 'marker-' + idx})
.attr("viewBox", "0 -5 10 10")
.attr("refX", function(link, idx){
return 10 + link.target.size;
})
.attr("refY", 0)
.attr("markerWidth", 6)
.attr("markerHeight", 6)
.attr("orient", "auto")
.append("svg:path")
.attr("d", "M0,-5L10,0L0,5")
.attr("fill", function(link){
if(link.type == 'in')
return "green";
return "blue";
});
Now there is one little problem with the fact that the line is curve. This means that the marker/arrow should be translated not only on the X axis, but also on the Y axis, of a value which probably depends on the ray of the curve...
A bit late to answer, but combining all previous answers, I have come up with a comprehensive solution that works for me in d3 v4, written in TypeScript because Angular (in case you find the lack of global variables curious). Below is a snippet containing the key components to include (because my entire production code is way too long and under NDA). Key ideas are annotated as code comments. The end result looks like this:
First of all, since you have tried to make nodes of different sizes, I will assume you have a radius property inside your nodes data. Let's say it is an array of objects like this:
{
id: input.name,
type: input.type,
radius: input.radius
}
Then markers are appended. Note that the size of each arrow (or marker) is 10, and half of it is 5. You can assign it as a variable like #ɭɘ-ɖɵʊɒɼɖ-江戸 did in his answer, but I am just too lazy.
let marker = svg.append("defs")
.attr("class", "defs")
.selectAll("marker")
// Assign a marker per link, instead of one per class.
.data(links, function (d) { return d.source.id + "-" + d.target.id; });
// Update and exit are omitted.
// Enter
marker = marker
.enter()
.append("marker")
.style("fill", "#000")
// Markers are IDed by link source and target's name.
// Spaces stripped because id can't have spaces.
.attr("id", function (d) { return (d.source.id + "-" + d.target.id).replace(/\s+/g, ''); })
// Since each marker is using the same data as each path, its attributes can similarly be modified.
// Assuming you have a "value" property in each link object, you can manipulate the opacity of a marker just like a path.
.style("opacity", function (d) { return Math.min(d.value, 1); })
.attr("viewBox", "0 -5 10 10")
// refX and refY are set to 0 since we will use the radius property of the target node later on, not here.
.attr("refX", 0)
.attr("refY", 0)
.attr("markerWidth", 5)
.attr("markerHeight", 5)
.attr("orient", "auto")
.append("path")
.attr("d", "M0,-5L10,0L0,5")
.merge(marker);
Then, the path can reference each individual marker with its ID:
let path = svg.append("g")
.attr("class", "paths")
.selectAll("path")
.data(links, function (d) { return d.source.id + "-" + d.target.id; });
// Update and exit are omitted.
// Enter
path = path
.enter()
.append("path")
.attr("class", "enter")
.style("fill", "none")
.style("stroke", "#000")
.style("stroke-opacity", function (d) { return Math.min(d.value, 1); })
// This is how to connect each path to its respective marker
.attr("marker-end", function(d) { return "url(#" + (d.source.id + "-" + d.target.id).replace(/\s+/g, '') + ")"; })
.merge(path);
One optional thing to modify if you want more features: Allow your .on("tick", ticked) listener to receive more variables to test for boundaries. For example, the width and height of the svg.
.on("tick", function () { ticked(node, path, width, height) })
And here is your new ticked function, based on the answer of #ɭɘ-ɖɵʊɒɼɖ-江戸 :
ticked(node, path, width, height) {
node
.attr("transform", function(d){return "translate(" + Math.max(d.radius, Math.min(width - d.radius, d.x)) + "," + Math.max(d.radius, Math.min(height - d.radius, d.y)) + ")"});
path
.attr("d", d => {
let dx = d.target.x - d.source.x,
dy = d.target.y - d.source.y,
dr = Math.sqrt(dx * dx + dy * dy),
gamma = Math.atan2(dy, dx), // Math.atan2 returns the angle in the correct quadrant as opposed to Math.atan
sx = Math.max(d.source.radius, Math.min(width - d.source.radius, d.source.x + (Math.cos(gamma) * d.source.radius) )),
sy = Math.max(d.source.radius, Math.min(height - d.source.radius, d.source.y + (Math.sin(gamma) * d.source.radius) )),
// Recall that 10 is the size of the arrow
tx = Math.max(d.target.radius, Math.min(width - d.target.radius, d.target.x - (Math.cos(gamma) * (d.target.radius + 10)) )),
ty = Math.max(d.target.radius, Math.min(height - d.target.radius, d.target.y - (Math.sin(gamma) * (d.target.radius + 10)) ));
// If you like a tighter curve, you may recalculate dx dy dr:
//dx = tx - sx;
//dy = ty - sy;
//dr = Math.sqrt(dx * dx + dy * dy);
return "M" + sx + "," + sy + "A" + dr + "," + dr + " 0 0,1 " + tx + "," + ty;
});
}
As mentioned by #joshua-comeau, it should be a plus sign when calculating sx and sy.
Here my solution :
First I calculate the angle with horizontal axes of the path (gamma). Then I get the X component (Math.cos(gamma) * radius) and Y component (Math.sin(gamma) * radius) of the radius. Then offset the ends of the path by those components.
function linkArc(d) {
var t_radius = calcRadius(d.target.size);
var s_radius = calcRadius(d.source.size);
var dx = d.target.x - d.source.x;
var dy = d.target.y - d.source.y;
var gamma = Math.atan(dy / dx);
var tx = d.target.x - (Math.cos(gamma) * t_radius);
var ty = d.target.y - (Math.sin(gamma) * t_radius);
var sx = d.source.x - (Math.cos(gamma) * s_radius);
var sy = d.source.y - (Math.sin(gamma) * s_radius);
return "M" + sx + "," + sy + "L" + tx + "," + ty;
}
First you will notice I am not using arcs but the principle should be the same.
Also my nodes have a size property from which I calculate the diameter of the circle.
Finally my marker is defined as is:
var arrowsize = 10;
var asHalf = arrowsize / 2;
svg.append("defs").selectAll("marker")
.data(["arrowhead"])
.enter().append("marker")
.attr("id", function (d) {
return d;
})
.attr("viewBox", "0 -5 " + arrowsize + " " + arrowsize)
.attr("refX", arrowsize)
.attr("refY", 0)
.attr("markerWidth", 9)
.attr("markerHeight", 9)
.attr("orient", "auto")
.attr("class", "arrowhead-light")
.append("path")
.attr("d", "M 0," + (asHalf * -1) + " L " + arrowsize + ",0 L 0," + asHalf);
I haven't found a way to control every single copy of the marker.

d3 drawing arrows tips

In this example :
http://jsfiddle.net/maxl/mNmYH/2/
If I enlarge the circles, ex:
var radius = 30; // (is 6 in the jsFiddle)
var circle = svg.append("svg:g").selectAll("circle")
.data(force.nodes())
.enter().append("svg:circle")
.attr("r", radius)
What is the best way to properly adjust the drawing of the arrow
so that it points to the radius of the circle ?
Thanks
You asked for the "best way to properly adjust the drawing of the arrow ".
I cannot claim the following approach is the "best" way, and I look forward to other answers, but here is one method to tackle this issue.
http://jsfiddle.net/Y9Qq3/2/
Relevant updates are noted below.
...
var w = 960,
h = 500
markerWidth = 6,
markerHeight = 6,
cRadius = 30, // play with the cRadius value
refX = cRadius + (markerWidth * 2),
refY = -Math.sqrt(cRadius),
drSub = cRadius + refY;
...
svg.append("svg:defs").selectAll("marker")
.data(["suit", "licensing", "resolved"])
.enter().append("svg:marker")
.attr("id", String)
.attr("viewBox", "0 -5 10 10")
.attr("refX", refX)
.attr("refY", refY)
.attr("markerWidth", markerWidth)
.attr("markerHeight", markerHeight)
.attr("orient", "auto")
.append("svg:path")
.attr("d", "M0,-5L10,0L0,5");
...
function tick() {
path.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 - drSub) + "," + (dr - drSub) + " 0 0,1 " + d.target.x + "," + d.target.y;
});
...

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