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>
​
​
​
.line {
  fill: none;
  stroke: steelblue;
  stroke-width: 1.5px;
  clip-path: url(#clip);
}
​
</style>
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.js"></script>
<script>
​
  
var svg = d3.select("svg"),
    margin = {top: 20, right: 80, bottom: 60, left: 50},
    width = svg.attr("width") - margin.left - margin.right,
    height = svg.attr("height") - margin.top - margin.bottom;
    
  svg.append("defs").append("clipPath")
    .attr("id", "clip")
    .append("rect")
    .attr("width", width)
    .attr("height", height);
  
  var g = svg.append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var monthformat = d3.timeParse("%B");
var yearformat = d3.timeParse("%Y");
  
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); });
var xAxis1={};
var xAxis2={};
  
  
d3.tsv("data.tsv", type, function(error, data) {
  if (error) throw error;
 var zoom = d3.zoom()
    .scaleExtent([1, 32])
    .translateExtent([[0, 0], [width, height]])
    .extent([[0, 0], [width, height]])
    .on("zoom", zoomed);
  g.call(zoom);
​
  var cities = data.columns.slice(1).map(function(id) {
    return {
      id: id,
      values: data.map(function(d) {
        return {date: d.date, temperature: d[id]};
      })
    };
  });
​
  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; }); }),
    d3.max(cities, function(c) { return d3.max(c.values, function(d) { return d.temperature; }); })
  ]);
​
  z.domain(cities.map(function(c) { return c.id; }));
​
 var xAxis1=d3.axisBottom(x); 
  
  g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis1);
 var xAxis2=d3.axisBottom(x); 
  
  g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + (height+25)    + ")")
      .call(xAxis2);
​
  g.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisLeft(y))
      .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", "0.71em")
      .attr("fill", "#000")
      .text("Temperature, ºF");
​
  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); });
​
  city.append("text")
      .datum(function(d) { return {id: d.id, value: d.values[d.values.length - 1]}; })
      .attr("transform", function(d) { return "translate(" + x(d.value.date) + "," + y(d.value.temperature) + ")"; })
      .attr("x", 3)
      .attr("dy", "0.35em")
      .style("font", "10px sans-serif")
      .text(function(d) { return d.id; });
  function zoomed() {
     var t = d3.event.transform, xt = t.rescaleX(x);
     line.x(function(d) { return xt(d.date);});
       svg.selectAll("path.line").attr("d",function(d){return line(d.values); });
     svg.selectAll(".axis--x").call(xAxis1.scale(xt)).call(xAxis2.scale(xt));
​
    //svg.select(".x.axis").call(xAxis);
    //svg.select(".y.axis").call(yAxis);
    }
});
​
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>
​
    