Metis Class 5, #2 by sxywu

index.html

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
/*     i always delete that margin thing in the style  */
  </style>
</head>

<body>
  <script>
    
   // let's define the margins
   var margin = {top: 20, right: 20, bottom: 20, left: 50};
   var width = 600 - margin.right - margin.left;
   var height = 300 - margin.top - margin.bottom;
   // let's do smaller numbers so that we can see
   // what now?
   var svg = d3.select('body')
   	.append('svg')
    .attr('width', width + margin.right + margin.left)
   	.attr('height', height + margin.top + margin.bottom)
   	// <g> is an SVG group element, and everything
    // within it (circle, rect, line, path, etc.) is relative to it
   	.append('g')
   		.attr('transform', 'translate(' + [margin.left, margin.top] + ')');
     
// load data
var url = 'https://raw.githubusercontent.com/thisismetis/sf16_dataviz2/master/class05/incomes.csv?token=ABYaAQeuKqG3rafZDHXI6azZ__twa65cks5YKn0JwA%3D%3D';
    d3.csv(url, function(data) {
      var filteredData = data.filter(function(d) {
        return d.cutoff === 'cop50';
      });
      filteredData.forEach(function(d) {
        d.val = +d.val;
        d.year = +d.year;
      });
      
      var incomeByCountry = d3.nest()
      	.key(function(d) {return d.country})
      	.entries(filteredData);
      
      // scales!!
      // y is linear because income value is
      // continuous (but you can use log scale, power scale, etc.)
      var yScale = d3.scaleLinear()
      	.range([height, 0])
      // what to use for domain is a lot of trial and error
      // for that matter, which scale to use is
      // also just trial and error to see what looks good
      	.domain(
          [d3.min(filteredData, function(d) {return d.val}) - 5000,
          d3.max(filteredData, function(d) {return d.val}) + 5000]
                 );
      // let's just keep it simple, and use scaleLinear for x-scale also
      // (they're all just years)
      var xScale = d3.scaleLinear()
      	.range([0, width])
      	.domain(d3.extent(filteredData, function(d) {return d.year}));
      
      var yAxis = d3.axisLeft()
      	.scale(yScale)
      	.tickFormat(d3.format('$,'));
      var xAxis = d3.axisBottom()
      	.scale(xScale)
      	.tickFormat(d3.format(''));
      
      // now we gotta draw the axes
      svg.append('g')
      	.call(yAxis);
      svg.append('g')
      	.attr('transform', 'translate(' + [0, height] + ')')
      	.call(xAxis);
      
      // and draw the line!
      // we're only drawing one line, do we need to select all?
      var line = d3.line()
      	.x(function(d) {return xScale(d.year)})
      	.y(function(d) {return yScale(d.val)});
      	
      console.log(incomeByCountry)
      svg.selectAll('path')
      	.data(incomeByCountry)
      	.enter().append('path')
      	.attr('d', function(d) {return line(d.values)})
      	.attr('fill', 'none')
      	// (if statement) ? (then do this) : (else do this)
      	.attr('stroke', function(d) {return d.key === 'United States' ? 'steelblue' : 'gray'})
      	.attr('stroke-width', function(d) {return d.key === 'United States' ? 3 : 1});
    })

  </script>
</body>