This is a follow on from the simple d3.js graph used as an example in the book D3 Tips and Tricks.
It impliments a simple tooltip which can also be found here and here. This implimentation is designed as a simple example which will be built on to create a slightly more complex example. It should be taken in context with the text of the book which can be downloaded for free from Leanpub.
<!DOCTYPE html>
<meta charset="utf-8">
<style> /* set the CSS */
body { font: 12px Arial;}
path {
stroke: steelblue;
stroke-width: 2;
fill: none;
}
.axis path,
.axis line {
fill: none;
stroke: grey;
stroke-width: 1;
shape-rendering: crispEdges;
}
</style>
<body>
<!-- load the d3.js library -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<script>
// Set the dimensions of the canvas / graph
var margin = {top: 30, right: 20, bottom: 30, left: 50},
width = 600 - margin.left - margin.right,
height = 270 - margin.top - margin.bottom;
// Parse the date / time
var parseDate = d3.time.format("%d-%b-%y").parse;
bisectDate = d3.bisector(function(d) { return d.date; }).left;
// Set the ranges
var x = d3.time.scale().range([0, width]);
var y = d3.scale.linear().range([height, 0]);
// Define the axes
var xAxis = d3.svg.axis().scale(x)
.orient("bottom").ticks(5);
var yAxis = d3.svg.axis().scale(y)
.orient("left").ticks(5);
// Define the line
var valueline = d3.svg.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.close); });
// Adds the svg canvas
var svg = d3.select("body")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform",
"translate(" + margin.left + "," + margin.top + ")");
var lineSvg = svg.append("g");
var focus = svg.append("g")
.style("display", "none");
// Get the data
d3.csv("atad.csv", function(error, data) {
data.forEach(function(d) {
d.date = parseDate(d.date);
d.close = +d.close;
});
// Scale the range of the data
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.close; })]);
// Add the valueline path.
lineSvg.append("path")
.attr("class", "line")
.attr("d", valueline(data));
// Add the X Axis
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
// Add the Y Axis
svg.append("g")
.attr("class", "y axis")
.call(yAxis);
// append the circle at the intersection
focus.append("circle")
.attr("class", "y")
.style("fill", "none")
.style("stroke", "blue")
.attr("r", 4);
// append the rectangle to capture mouse
svg.append("rect")
.attr("width", width)
.attr("height", height)
.style("fill", "none")
.style("pointer-events", "all")
.on("mouseover", function() { focus.style("display", null); })
.on("mouseout", function() { focus.style("display", "none"); })
.on("mousemove", mousemove);
function mousemove() {
var x0 = x.invert(d3.mouse(this)[0]),
i = bisectDate(data, x0, 1),
d0 = data[i - 1],
d1 = data[i],
d = x0 - d0.date > d1.date - x0 ? d1 : d0;
focus.select("circle.y")
.attr("transform",
"translate(" + x(d.date) + "," +
y(d.close) + ")");
}
});
</script>
</body>
date,close
26-Mar-12,606.98
27-Mar-12,614.48
28-Mar-12,617.62
29-Mar-12,609.86
30-Mar-12,599.55
2-Apr-12,618.63
3-Apr-12,629.32
4-Apr-12,624.31
5-Apr-12,633.68
9-Apr-12,636.23
10-Apr-12,628.44
11-Apr-12,626.20
12-Apr-12,622.77
13-Apr-12,605.23
16-Apr-12,580.13
17-Apr-12,543.70
18-Apr-12,443.34
19-Apr-12,345.44
20-Apr-12,234.98
23-Apr-12,166.70
24-Apr-12,130.28
25-Apr-12,99.00
26-Apr-12,89.70
27-Apr-12,67.00
30-Apr-12,53.98
1-May-12,58.13