D3 Examples - Multi-Series Line Chart

Multi-Series Line Chart

This line chart is constructed from a TSV file storing the daily average temperatures of New York, San Francisco and Austin over the last year. The chart employs conventional margins and a number of D3 features:

d3.tsv - load and parse data

d3.time.format - parse dates

d3.time.scale - x-position encoding

d3.scale.linear - y-position encoding

d3.scale.category10, a d3.scale.ordinal - color encoding

d3.extent, d3.min and d3.max - compute domains

d3.keys - compute column names

d3.svg.axis - display axes

d3.svg.line - display line shape

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
body {
  font: 10px sans-serif;
  background-color: #F5F5F5;
}
​
.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}
​
.x.axis path,
.x.axis line,
.y.axis path,
.y.axis line {
  fill: none;
  stroke: #A9A9A9;
  
}
​
.x.axis text,
.y.axis text {
    stroke: #A9A9A9;
  stroke-width: 0.5px;
}
  
.line {
  fill: none;
  stroke: steelblue;
  stroke-width: 1.5px;
}
​
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
​
var margin = {top: 20, right: 80, bottom: 30, left: 70},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;
​
var parseDate = d3.time.format("%Y%m%d").parse;
  
 
var degreeFormat = d3.format("0.0f");
  
var count = 0;
  
var x = d3.time.scale()
    .range([0, width]);
​
var y = d3.scale.linear()
    .range([height, 0]);
​
var color = d3.scale.category10();
​
var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom");
​
var yAxis = d3.svg.axis()
    .scale(y)
    .orient("right")
        .tickFormat(function(d){
      return degreeFormat(d) + "º";
    });
  
var line = d3.svg.line()
    .interpolate("linear")
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.temperature); });
​
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) {
  if (error) throw error;
​
  color.domain(d3.keys(data[0]).filter(function(key) { return key !== "date"; }));
​
  data.forEach(function(d) {
    d.date = parseDate(d.date);
  });
​
  var cities = color.domain().map(function(name) {
    return {
      name: name,
      values: data.map(function(d) {
        return {date: d.date, temperature: +d[name]};
      })
    };
  });
​
  x.domain(d3.extent(data, function(d) { return d.date; }));
​
  y.domain([
    d3.min(cities, function(c) { return d3.min(c.values, function(v) { return v.temperature; }); }),
    d3.max(cities, function(c) { return d3.max(c.values, function(v) { return v.temperature; }); })
  ]);
​
  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);
​
  svg.append("g")
      .attr("class", "y axis")
        .attr("transform", "translate(" +  width + "," + 0 + ")")
      .call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", -12)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Temp (ºF)");
​
  var city = svg.selectAll(".city")
      .data(cities)
    .enter().append("g")
      .attr("class", "city");
​
  city.append("path")
      .attr("class", "line")
      .attr("d", function(d) { return line(d.values); })
      .style("stroke", function(d) { return color(d.name); });
​
  city.append("text")
      .datum(function(d) { return {name: d.name, value: d.values[d.values.length -                  1]}; })
        .attr("fill", function(d) {
            return color(d.name);
            })
      .attr("transform", function(d) { 
                    return "translate(" + x(d.value.date) + "," + y(d.value.temperature) + ")"; 
        })
        .attr("orient", "left")
      .attr("x", 0)
      .attr("dy", ".35em")
      .text(function(d) { return d.name; });
});
​
</script>
​
    