# Creating a Pie Chart
## Set Up
```html
```
## Set Config Vars
```javascript
var WIDTH = 360;
var HEIGHT = 360;
var radius = Math.min(WIDTH, HEIGHT) / 2;
var dataset = [
{ label: 'Abulia', count: 10 },
{ label: 'Betelgeuse', count: 20 },
{ label: 'Cantaloupe', count: 30 },
{ label: 'Dijkstra', count: 40 }
];
```
## Create an Ordinal Scale
An ordinal scale maps discrete values (can't be interpolated) to discrete values.
```javascript
var mapper = d3.scaleOrdinal();
mapper.range([45, 63, 400]);
mapper.domain(['Bob', 'Sally', 'Zagthor']);
console.log(mapper('Bob'));
console.log(mapper('Sally'));
console.log(mapper('Zagthor'));
```
You cannot invert ordinal scales:
```javascript
console.log(mapper.invert(45));
```