Ch. 4, Fig. 4 - D3.js in Action

This is the code for Chapter 4, Figure 4 from D3.js in Action showing how to create a scatterplot using scales and d3.extent() to calculate min and max values for data.

<html>
<head>
  <title>D3 in Action Chapter 4 - Example 2</title>
  <meta charset="utf-8" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
</head>
<style>
  svg {
    height: 500px;
    width: 500px;
    border: 1px solid gray;
  }

</style>
<body>

<div id="viz">
  <svg>
  </svg>
</div>
</body>
  <footer>
    
<script>
var scatterData = [{friends: 5, salary: 22000}, {friends: 3, salary: 18000}, {friends: 10, salary: 88000}, {friends: 0, salary: 180000}, {friends: 27, salary: 56000}, {friends: 8, salary: 74000}]

xExtent = d3.extent(scatterData, function(d) {return d.salary});
yExtent = d3.extent(scatterData, function(d) {return d.friends});
xScale = d3.scale.linear().domain(xExtent).range([0,500]);
yScale = d3.scale.linear().domain(yExtent).range([0,500]);

d3.select("svg")
.selectAll("circle")
.data(scatterData)
.enter()
.append("circle")
.attr("r", 5)
.attr("cx", function(d) {return xScale(d.salary)})
.attr("cy", function(d) {return yScale(d.friends)})

</script>
  </footer>

</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js