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>
​
/* .axis--x path {
  display: ;
}
 */
  
.line {
  fill: none;
  stroke: steelblue;
  stroke-width: 1.5px;
}
  
  .cities{
    padding:-20;
  }
​
</style>
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
​
var svg = d3.select("svg"),
    margin = {top: 20, right: 80, bottom: 30, left: 68},
    width = svg.attr("width") - margin.left - margin.right,
    height = svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var parseTime = d3.timeParse("%Y%m%d");
​
var x = d3.scaleTime().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    z = d3.scaleOrdinal(d3.schemeCategory10);
​
var line = d3.line()
//     .curve(d3.curveBasis)
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.temperature); });
​
d3.tsv("data.tsv", type, function(error, data) {
  if (error) throw error;
​
 var cities = data.columns.slice(1).map(function(id) {
    return {
      id: id,
      values: data.map(function(d) {
        return {date: d.date, temperature: d[id]
               //do something
               };
      })
    };
  });
​
  x.domain(d3.extent(data, function(d) { return d.date; }));
​
  y.domain([
    d3.min(cities, function(c) { return d3.min(c.values, function(d) { return d.temperature; })-5 ; }),
    d3.max(cities, function(c) { return d3.max(c.values, function(d) { return d.temperature; })+5; })
  ]);
​
  z.domain(cities.map(function(c) { return c.id; }));
​
  g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x));
​
  g.append("g")
      .attr("class", "axis axis--y")
            .attr("transform", "translate("+width+",0)")
      .call(d3.axisRight(y).tickFormat(function(d) {return d+"º";}))   
            .append("text")
        .attr("transform", "rotate(90)")
        .attr("y", 6)
        .attr("dy", "0.71em")
        .attr("fill", "#000")
        .text("Fahrenheit");
​
  var city = g.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 z(d.id); });
​
  var max = d3.max(cities, function(c) { 
    return d3.max(c.values, function(d) { 
      return d.temperature; }); });
​
  var min = d3.min(cities, function(c) {
    return d3.min(c.values, function(d) { 
      return d.temperature; }) ; });
  var temps = [min,max];
    var marks = city.append("g")
//     .selectAll("circle")
//     .data(function(d) {return d.values;})
        .selectAll("circle")
        .data(function(d) {
      // add name inside each value inside `d.values`
      d.values.forEach(function(value) {
        
        value.name = d.id;
//         
      })
    return d.values;}).enter();
  
    marks.append("circle")
            .attr("r", 2)
        .attr("cx", function(d){return x(d.date)})
        .attr("cy", function(d){return y(d.temperature)})
        .style("fill", function(d) {return z(d.name);});
    
  marks.append("text")
//          .attr("x", function(d) { return x(function(d){
//              if(d.temperature == max){
            
//             return d.date;
            
//           }})})
    .attr("x", function(d) { 
            if(d.value == max){
          console.log(d);
          return x(d.max.date);
        }})
​
        .attr("y", max)
    .text(max)
            .style("font", "10px sans-serif")
            .style("fill", function(d) {return z(d.name);});
​
//  var points = marks.selectAll("circle")
//              .text(function(d){
// //         if(d.value == max){
// //           console.log(d.value);
//           return d.value;
//         });
  city.append("text")
      .datum(function(d) { 
    return {
      id: d.id, value: d.values[0]}; 
    })
​
       .attr("transform", function(d) { return "translate(" + x(d.value.date)+ "," + y(d.value.temperature) + ")"; })
      .attr("x",-1.64 )
      .attr("dy", function(d) { 
                if(d.id == "San Francisco"){
            return "1em";
          }
        else{
            return ".35em";} })
//          .attr("dx", "-0.35em")
      .style("font", "10px sans-serif")
        .style("text-anchor","end") 
      .style("fill", function(d) { return z(d.id); })
      .text(function(d) { return d.id; })
});
​
function type(d, _, columns) {
  d.date = parseTime(d.date);
  for (var i = 1, n = columns.length, c; i < n; ++i) d[c = columns[i]] = +d[c];
  return d;
}
​
</script>
​
    