D3/examples/barchart04_scale.html at master · Godfather27/D3 · GitHub

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<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <script src="https://cdn.polyfill.io/v2/polyfill.min.js"></script>
  <script src="../web_modules/d3/build/d3.js"></script>
  <style type="text/css">
    body {
      width: 800px;
      margin: 25px auto;
      font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;
    }
    rect {
      fill: steelblue;
      fill-opacity: 0.8;
    }
    rect:hover {
      fill-opacity: 1;
    }
    .axis {
      font-size: smaller;
    }
  </style>
</head>
<body>
  <h1>Student's First BarChart</h1>

  <script type="text/javascript">

  const margin = {top: 40, bottom: 10, left: 120, right: 20};
  const width = 800 - margin.left - margin.right;
  const height = 600 - margin.top - margin.bottom;

  // Creates sources <svg> element
  const svg = d3.select('body').append('svg')
              .attr('width', width+margin.left+margin.right)
              .attr('height', height+margin.top+margin.bottom);

  // Group used to enforce margin
  const g = svg.append('g')
              .attr('transform', `translate(${margin.left},${margin.top})`);

  // Global variable for all data
  var data;

  const bar_height = 50;

  /////////////////////////
  // TODO create an x and y scale and axis
  // x a lienar scale with range: [0, width] and domain from 0 max temperature
  // y a band ordinal scale range: [0, height] and domain the different cities

  d3.json('weather.json', function(json) {
    data = json;

    update(data);
  });

  function update(new_data) {
    const scales = setScales(new_data);
    // Render the chart with new data

    // DATA JOIN
    const rect = g.selectAll('rect').data(new_data);

    // ENTER
    // new elements
    const rect_enter = rect.enter().append('rect')
      .attr('x', 0)
    rect_enter.append('title');

    // ENTER + UPDATE
    // both old and new elements
    rect.merge(rect_enter)
      .attr('height', bar_height)
      .attr('width', (d) => scales.scaleX(d.temperature))
      .attr('y', (d, i) => scales.scaleY(i * (bar_height + 5)));

      rect.merge(rect_enter).select('title').text((d) => d.location.city);

      // EXIT
      // elements that aren't associated with data
      rect.exit().remove();

  }

  function setScales(new_data){
    // X SCALE
      // get setup data
    const maxTemp = Math.max(...new_data.map(d=>d.temperature));

      // set d3 elements
    const scaleX = d3.scaleLinear().domain([0, maxTemp]).range([0, width]);
    const axisX = d3.axisTop().scale(scaleX);
    const axis_containerX = d3.select('svg').append('g')
      .attr('class', 'axis')
      .attr('transform', `translate(${margin.left},${margin.top})`);

    // Y SCALE
      // get setup data
    const cities = new_data.map(v => v.location.city);
    const rangesY = new_data.map((v,i) => (bar_height + 5) * i);

      // set d3 elements
    const scaleY = d3.scaleOrdinal().domain(cities).range(rangesY);
    const axisY = d3.axisLeft().scale(scaleY);
    const axis_containerY = d3.select('svg').append('g')
      .attr('class', 'axis')
      .attr('transform', `translate(${margin.left},${margin.top})`);

    // scale axis containers
    axis_containerX.call(axisX)
    axis_containerY.call(axisY)

    return {scaleX, scaleY}
  }

  </script>
</body>
</html>