Line charts with dot annotation

Line charts with circles and labels. A demonstration of the technique for a student.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 10px sans-serif;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.x.axis path {
  display: none;
}

.network-line {
  fill: none;
  stroke: steelblue;
  stroke-width: 3px;
}

</style>
<body>

var margin = {top: 20, right: 80, bottom: 30, left: 50},
    width = 700 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

var x = d3.scale.linear()
    .range([0, width])
    .domain([2002,2012])

var y = d3.scale.linear()
    .range([height, 0]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .tickFormat(function(d) { return d});

var yAxis = d3.svg.axis()
    .scale(y)
    .tickSize(-width)
    .orient("left");

var line = d3.svg.line()
    .x(function(d) { return x(d.year); })
    .y(function(d) { return y(d.val); });

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 + ")");

d3.tsv("data.tsv", function(error, data) {

data.forEach(function(d) {
    d.year = +d.year;
    d.val = +d.val;
  });

yearlyCostByNetwork = d3.nest()
      .key(function(d) { return d.network})
      .entries(data);

y.domain([0,d3.max(data.map(function(d) { return d.val; }))]);

svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

svg.append("g")
      .attr("class", "y axis")
      .call(yAxis);

var linesContainer = svg.append("g")

linesContainer.selectAll(".network-line")
      .data(yearlyCostByNetwork)
      .enter()
      .append("path")
      .attr("class", "network-line")
      .attr("d", function(d) { return line(d.values); });

var labelElements = svg.append("g")
      .attr("class", "fiddly-bits")

var label = labelElements.selectAll(".g-label-element")
      .data(data.filter(function(d) { return d.year == 2012; }))
    .enter().append("g")
      .attr("class", "g-label-element")
      .attr("transform", function(d) { return "translate(" + x(d.year) + "," + y(d.val) + ")"; } );

label.append("circle")
      .attr("r", 4)

label.append("text")
      .attr("x", 10)
      .text(function(d) { return d.network})

});

</script>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js