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Created September 8, 2011 15:15
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Simple Pie Chart example with D3.js
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index.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8">
<title>Testing Pie Chart</title>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js?2.1.3"></script>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.geom.js?2.1.3"></script>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.layout.js?2.1.3"></script>
<style type="text/css">
.slice text {
font-size: 16pt;
font-family: Arial;
}
</style>
</head>
<body>
<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 = d3.select("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
.outerRadius(r);
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)
arcs.append("svg:path")
.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
</script>
</body>
</html>
@rioj7
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rioj7 commented Apr 1, 2020 •
edited

@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 = d3.select("body")
        .append("svg:svg")
            .attr("width", w)
            .attr("height", h)
        .append("svg:g")
            .attr("transform", "translate(" + r + "," + r + ")");

and add the data to the call to pie

var arcs = vis.selectAll("g.slice")
        .data(pie(data))
        .enter()
            .append("svg:g")
                .attr("class", "slice");

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