Skip to content

Instantly share code, notes, and snippets.

Created September 8, 2011 15:15
Show Gist options
  • Save enjalot/1203641 to your computer and use it in GitHub Desktop.
Save enjalot/1203641 to your computer and use it in GitHub Desktop.
Simple Pie Chart example with D3.js
<!DOCTYPE html>
<meta http-equiv="Content-type" content="text/html; charset=utf-8">
<title>Testing Pie Chart</title>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<style type="text/css">
.slice text {
font-size: 16pt;
font-family: Arial;
<script type="text/javascript">
var w = 300, //width
h = 300, //height
r = 100, //radius
color = d3.scale.category20c(); //builtin range of colors
data = [{"label":"one", "value":20},
{"label":"two", "value":50},
{"label":"three", "value":30}];
var vis ="body")
.append("svg:svg") //create the SVG element inside the <body>
.data([data]) //associate our data with the document
.attr("width", w) //set the width and height of our visualization (these will be attributes of the <svg> tag
.attr("height", h)
.append("svg:g") //make a group to hold our pie chart
.attr("transform", "translate(" + r + "," + r + ")") //move the center of the pie chart from 0, 0 to radius, radius
var arc = d3.svg.arc() //this will create <path> elements for us using arc data
var pie = d3.layout.pie() //this will create arc data for us given a list of values
.value(function(d) { return d.value; }); //we must tell it out to access the value of each element in our data array
var arcs = vis.selectAll("g.slice") //this selects all <g> elements with class slice (there aren't any yet)
.data(pie) //associate the generated pie data (an array of arcs, each having startAngle, endAngle and value properties)
.enter() //this will create <g> elements for every "extra" data element that should be associated with a selection. The result is creating a <g> for every object in the data array
.append("svg:g") //create a group to hold each slice (we will have a <path> and a <text> element associated with each slice)
.attr("class", "slice"); //allow us to style things in the slices (like text)
.attr("fill", function(d, i) { return color(i); } ) //set the color for each slice to be chosen from the color function defined above
.attr("d", arc); //this creates the actual SVG path using the associated data (pie) with the arc drawing function
arcs.append("svg:text") //add a label to each slice
.attr("transform", function(d) { //set the label's origin to the center of the arc
//we have to make sure to set these before calling arc.centroid
d.innerRadius = 0;
d.outerRadius = r;
return "translate(" + arc.centroid(d) + ")"; //this gives us a pair of coordinates like [50, 50]
.attr("text-anchor", "middle") //center the text on it's origin
.text(function(d, i) { return data[i].label; }); //get the label from our original data array
Copy link

mslevin commented Aug 7, 2014

@stevematdavies The resulting pie chart is quite simple.

Copy link

How can I get the data from a Backbone model?

Copy link

Question: why do you have to put [data] in the extra level of array when creating the outer svg element? The code doesn't work if you just pass data to the data() function:
.data(data) // fails
.data([data]) // works

I really don't understand this.

Copy link

How do i assign the code to a function so i can just call it on a different data set later

Copy link

rioj7 commented Apr 1, 2020

@bethrobson The current selection only contains 1 element, the svg tag. You want to attach the whole of data so it will be passed on to the child tags of svg. You do this by creating an array with 1 element and bind that to the selection. If you do .data(data) you only bind the first data-point to the svg.

An alternative is not to bind anything to the svg

var vis ="body")
            .attr("width", w)
            .attr("height", h)
            .attr("transform", "translate(" + r + "," + r + ")");

and add the data to the call to pie

var arcs = vis.selectAll("g.slice")
                .attr("class", "slice");

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment