D3 Examples - backtesting

backtesting
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>
  .tooltip {
    background-color: white;
    border: 1px solid lightgray;
  }
  .line {
    fill: none;
    stroke: steelblue;
    stroke-width: 1.5px;
  }
  .hover-line {
    stroke: gray;
    stroke-width: 1px;
    stroke-dasharray: 3,3;
  }
  .overlay {
    fill: none;
    pointer-events: all;
  }
  
  .axis text {
    fill: gray;
  }
  
  .axis path {
    stroke: gray;
  }
  
  .tick line {
    stroke: gray
  }
  
  .tick text {
    fill: gray
  }
</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
  
var actual = [ 
  {
    date: "2006-04",
    value: 27000
  },
  {
    date: "2006-07",
    value: 27000
  },
  {
    date: "2006-10",
    value: 42000
  },
  {
    date: "2007-01",
    value: 32000
  },
  {
    date: "2007-04",
    value: 33000
  },
  {
    date: "2007-07",
    value: 41000
  },
  {
    date: "2007-10",
    value: 42000
  },
  {
    date: "2008-01",
    value: 71000
  },
  {
    date: "2008-04",
    value: 74000
  },
  {
    date: "2008-07",
    value: 76000
  }
];
var predicted = [
  {
    date: "2006-04",
    value: 27000
  },
  {
    date: "2006-07",
    value: 28000
  },
  {
    date: "2006-10",
    value: 44000
  },
  {
    date: "2007-01",
    value: 33000
  },
  {
    date: "2007-04",
    value: 34000
  },
  {
    date: "2007-07",
    value: 41000
  },
  {
    date: "2007-10",
    value: 38000
  },
  {
    date: "2008-01",
    value: 65000
  },
  {
    date: "2008-04",
    value: 63000
  },
  {
    date: "2008-07",
    value: 63000
  }
];
  
var bisectDate = d3.bisector(function(d) { return d.date; }).left;
var parseTime = d3.timeParse("%Y-%m");
  
actual.forEach(function (item) {
  item.date = parseTime(item.date)
})
​
predicted.forEach(function (item) {
  item.date = parseTime(item.date)
})
  
var svg = d3.select("svg"),
    margin = {top: 20, right: 80, bottom: 100, left: 50},
    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 x = d3.scaleTime().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    z = d3.scaleOrdinal(d3.schemeCategory10);
​
var xAxis = d3.axisBottom(x)
    .tickFormat(d3.timeFormat("%Y-%m"));
var yAxis = d3.axisLeft(y);
var line = d3.line()
    .y(function(d) { return y(d.value); })
    .x(function(d) { return x(d.date); });
  
var xGroup = g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")"); 
  
 var yGroup = g.append("g")
      .attr("class", "axis axis--y");
  
  var data = [
    {
      id: "actual",
      values: actual
    },
    {
      id: "predicted",
      values: predicted
    }
  ]
  
  x.domain([
    d3.min(data, function(c) { return d3.min(c.values, function(d) { return d.date; }); }),
    d3.max(data, function(c) { return d3.max(c.values, function(d) { return d.date; }); })
  ]);
​
  y.domain([
    d3.min(data, function(c) { return d3.min(c.values, function(d) { return d.value; }); }),
    d3.max(data, function(c) { return d3.max(c.values, function(d) { return d.value; }); })
  ]);
​
  z.domain(data.map(function(c) { return c.id; }));
  
  
  xGroup.call(xAxis)
    .selectAll("text")  
        .style("text-anchor", "end")
        .attr("dx", "-.8em")
        .attr("dy", ".15em")
        .attr("transform", "rotate(-65)");
  yGroup.call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", "0.71em")
      .attr("fill", "#000")
      .text("$");;
​
  
  var focus = g.append("g")
        .attr("class", "focus")
        .style("display", "none");
  
  
  var city = g.selectAll(".city")
    .data(data)
    .enter().append("g")
      .attr("class", "city")
        
  var paths = city.append("path")
      .attr("class", "line")
      .attr("d", function(d) {return line(d.values); })
      .style("stroke", function(d) { return z(d.id); })
        .attr("id", function(d) {
        return d.id.substring(0, 3).toUpperCase();
      })
​
  
  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.value) + ")"; })
      .attr("x", 3)
      .attr("dy", "0.35em")
      .style("font", "13px sans-serif")
        .style("fill", function(d) { return z(d.id) })
        .text(function(d) { return d.id; })
    
        var hover = city.append("g")
        .attr("class", function(d) { return "hover hover-" + d.id; })
        .style("display", "none")
    
        hover.append("line")
        .attr("class", "x-hover-line hover-line")
        .attr("y1", 0)
        .attr("y2", height);
​
        hover.append("line")
        .attr("class", "y-hover-line hover-line")
        .attr("x1", width)
        .attr("x2", width);
  
            hover.append("circle")
        .attr("r", 5)
            .style("stroke", function(d) { return z(d.id) })
        .style("fill", "white")
        
      hover.append("text")
                .style("font", "13px sans-serif")
            .style("fill",  function(d) { return z(d.id) })
        .style("stroke", "white")
        .style("paint-order", "stroke")
        .style("stroke-width", "5")
      
    svg.append("rect")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
        .attr("class", "overlay")
        .attr("width", width)
        .attr("height", height)
        .on("mouseover", function() { hover.style("display", null); })
        .on("mouseout", function() { hover.style("display", "none"); })
        .on("mousemove", mousemove);
​
    function mousemove() {
      var x0 = x.invert(d3.mouse(this)[0])
      data.forEach(function (line) {        
       var  i = bisectDate(line.values, x0, 1),
            d0 = line.values[i - 1],
            d1 = line.values[i],
            d = x0 - d0.date > d1.date - x0 ? d1 : d0;
        var tooltip = d3.selectAll(".hover-" + line.id)
        tooltip.attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")");
        tooltip.selectAll("text").text("$" + d.value)
        tooltip.selectAll(".x-hover-line").attr("y2", height - y(d.value));
        tooltip.selectAll(".y-hover-line").attr("x2", width + width);
      })
      
        
    }
​
​
</script>
​
    