interactive-vis-course/Week8/bostock_bar_updates_simpler.html at gh-pages · arnicas/interactive-vis-course · GitHub

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<html lang="en">
  <head>
    <meta charset="utf-8">
<title>Object Constancy</title>
<style>

    body {
      background: #fcfcfa;
      color: #333;
      margin: 1em auto 4em auto;
      position: relative;
      width: 960px;
    }

    svg {
      font: 10px sans-serif;
    }

    .bar rect {
      fill: steelblue;
    }

    .bar rect:hover {
      fill: orange;
    }

    .value {
      fill: white;
    }

    .axis {
      shape-rendering: crispEdges;
    }

    .axis path {
      fill: none;
      stroke: none;
    }

    .x.axis path {
      fill: none;
      stroke: white;
    }

    .x.axis line {
      stroke: #fff;
      stroke-opacity: .8;
    }

    .y.axis path {
      stroke: black;
    }

</style>
</head>

<body>

<h2>Slightly Simplified Code from M. Bostock's Object Constancy Example</h2>


<p>Source of original: <a href="http://bost.ocks.org/mike/constancy/">http://bost.ocks.org/mike/constancy/</a></p>

<p id="menu"><b>Top States by Age Bracket, 2008</b><br>Age: <select></select>

<p id="chart"></p>

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js"></script>
<script>

  var fullwidth = 960,
    fullheight = 280;

  var margin = {top: 20, right: 40, bottom: 10, left: 40},
      width = fullwidth - margin.right - margin.left;
      height = fullheight - margin.top - margin.bottom;

  var percentFormat = d3.format(".1%"),
      states,
      prevAge;

  var xScale = d3.scale.linear()
      .range([0, width]);

  var yScale = d3.scale.ordinal()
      .rangeRoundBands([0, height], .1);

  var xAxis = d3.svg.axis()
      .scale(xScale)
      .orient("top")
      .tickFormat(percentFormat);

  var svg = d3.select("#chart").append("svg")
      .attr("width", fullwidth)
      .attr("height", fullheight)
      .style("margin-left", -margin.left + "px")
    .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

  svg.append("g")
      .attr("class", "x axis");

  svg.append("g")
      .attr("class", "y axis")
    .append("line")
      .attr("class", "domain")
      .attr("y2", height);

  var menu = d3.select("#menu select")
      .on("change", redraw);

  d3.csv("data/states-age.csv", function(data) {

    states = data;

    // remember d3.keys gets us the column names from these objects, using first row:
    var ages = d3.keys(states[0]).filter(function(key) {
      return key != "State" && key != "Total"; // this will return columns NOT MATCHING those
    });

    console.log(ages);

    // do some calculations for each percentage
    states.forEach(function(state) {
      ages.forEach(function(age) {
        state[age] = state[age] / state.Total;
      });
    });

  // build menu from the data; could have been done by hand.
    menu.selectAll("option")
        .data(ages)
      .enter().append("option")
        .text(function(d) { return d; });

    menu.property("value", "18 to 24 Years");
    // redraw in this case draws the UI - it uses a variable to determine data column.
    redraw();
  }); // end load csv


  function redraw() {

    // get the age for the data access off the menu:
    var currentAge = menu.property("value");

      // sort by it and then take the top 10 using slice!
    var top10 = states.sort(function(a, b) {
            return b[currentAge] - a[currentAge];
          })
          .slice(0, 10);

    yScale.domain(top10.map(function(d) { return d.State; })); // the y scale is ordinal, all the state names

    var bar = svg.selectAll(".bar")
        .data(top10, function(d) { return d.State; }); // key function!

    var barCreate = bar.enter().append("g")
        .attr("class", "bar")
        .attr("transform", function(d) { return "translate(0," + (yScale(d.State) + height) + ")"; })
        .style("fill-opacity", 0);

    console.log("age", prevAge); // this is undefined the first time thru.

    barCreate.append("rect")
        //.attr("width", age && function(d) { return x(d[age]); })
        .attr("width", function(d) {
          if (prevAge) {
            return xScale(d[prevAge]);
          }
        })
        .attr("height", yScale.rangeBand());

    barCreate.append("text")
        .attr("class", "label")
        .attr("x", -3)
        .attr("y", yScale.rangeBand() / 2)
        .attr("dy", ".35em")
        .attr("text-anchor", "end")
        .text(function(d) { return d.State; });

    barCreate.append("text")
        .attr("class", "value")
        //.attr("x", age && function(d) { return x(d[age]) - 3; })
        .attr("x", function(d) {
          if (prevAge) {
          return xScale(d[prevAge]) - 3;
          }
        })
        .attr("y", yScale.rangeBand() / 2)
        .attr("dy", ".35em")
        .attr("text-anchor", "end");

    prevAge = currentAge;
    // they are sorted, so take the top value for the max on the domain here:
    xScale.domain([0, top10[0][currentAge]]);

    // sets the d.yLocation for the bar that's used in the exit transition.
    var barUpdate = bar.transition()
        .attr("transform", function(d) {
          // set the value of the current y location for the exit move when it goes.
          d.yLocation = yScale(d.State);
          return "translate(0," + yScale(d.State) + ")"; })
        .style("fill-opacity", 1);

    barUpdate.select("rect")
        .attr("width", function(d) { return xScale(d[currentAge]); });

    barUpdate.select(".value")
        .attr("x", function(d) { return xScale(d[currentAge]) - 3; })
        .text(function(d) { return percentFormat(d[currentAge]); });

    var barExit = bar.exit().transition()
        .attr("transform", function(d) { return "translate(0," + (d.yLocation + height) + ")"; })
        .style("fill-opacity", 0)
        .remove();

    barExit.select("rect")
        .attr("width", function(d) { return xScale(d[currentAge]); });

    barExit.select(".value")
        .attr("x", function(d) { return xScale(d[currentAge]) - 3; })
        .text(function(d) { return percentFormat(d[currentAge]); });

        // transition the axis, so easy if you fixed the domain!
    svg.transition().select(".x.axis")
        .call(xAxis);
  }

</script>

</body>
</html>