interactive-vis-course/Week4/scale_examples.html at gh-pages · arnicas/interactive-vis-course · GitHub

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<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>Scales in D3</title>

        <style>
        body {
          padding: 50px;
          font-family: Verdana, sans-serif;
          font-size: 12pt;
        }
        p {
          margin-left: 20px;
          color: orange;
        }

        </style>
    </head>
    <body>

        <h1>Playing with Scales in D3</h1>

        <div id="linearScale">
        First scale, mapping values to new values:
        </div>

        <div id="colorScale1">
        Linear Color scale:
        </div>

        <div id="colorScale2">
        Ordinal color scale:
        <p>Apple
          <p>Orange
            <p>Pineapple
              <p>Cherry
                <p>Kumquat
                  <p>China
                    <p>Russia
                      <p>Japan
                        <p>India
                          <p>France
                            <p>Syria
                              <p>Madagascar
                                <p>SUV
        </div>


        <div id="colorScale3">
          This is another ordinal scale, with data mapped to specific values:
      </div>

    </body>

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

<script type="text/javascript">

  // this example is from Dashing D3:https://www.dashingd3js.com/d3js-scales

    var myData = [0, 1000, 3000, 2000, 5000, 4000, 7000, 6000, 9000, 8000, 10000];

    var newScaledData = [];
    var minDataPoint = d3.min(myData);
    var maxDataPoint = d3.max(myData);

    // Notice that domain and range take ARRAYS.

    var linearScale = d3.scale.linear()
                      .domain([minDataPoint,maxDataPoint])
                      .range([0,100]);

    // a shortcut for the max and min operation is:
    console.log(d3.extent(myData));

    // this is the same as above, but using the shortcut d3.extent:

    var linearScale = d3.scale.linear()
                      .domain(d3.extent(myData))
                      .range([0,100]);


    // Suppose we had objects, like from a CSV?

    myobjects = [
      {
      country : "USA",
      score : "42"
      },
      {
      country : "Belgium",
      score : "24"
      },
      {
      country : "Taiwan",
      score : "5"
      },
      {
      country : "Ireland",
      score : "35"
      },
      {
      country : "Tahiti",
      score : "05"
      }
    ];

    myobjMax = d3.max(myobjects, function(d) {
      return d.score;
    });

    console.log("max from d3.max on objects", myobjMax);

    myobjextents = d3.extent(myobjects, function(d) {
      return +d.score;
    });

    console.log("max and min array from d3.extent on objects", myobjextents);

    // Let's look at the scaled data from the original number data:

    console.log("the scaled value 3000 is now", linearScale(3000));

    myData.forEach(function(d, i){
        // we call the scale function with each element,
        // and put the result onto the new array:
        newScaledData.push(linearScale(d));
    });

    // we print the results in the div element
     // the join function just joins all the strings with the separator!
    d3.select("#linearScale").append("p").text(newScaledData.join(", "));

    var newData = [24, 54, 65, 100, 23, 43, 2, 35, 76, 47];

    // you can use hex etc values in here - i'm just using named colors now
    var colorScale = d3.scale.linear().domain(d3.extent(newData)).range(['gray','red']);

    // draw actual paragraphs with the colors:
    d3.select("#colorScale1")
      .selectAll("p")
      .data(newData)
      .enter()
      .append("p")
      .text(function (d) {
        return d;
      })
      .style("color", function(d) {
        return colorScale(d);
      });


    // one of many ordinal scale options for generating lists of colors in d3.
    var colors = d3.scale.category10();

    // this is still a function: it returns the colors by count:
    console.log(colors(0));

    // in this example, we select existing p's and restyle them!  Notice there are more than 10 items, and the colors start repeating:

    d3.select("#colorScale2")
      .selectAll("p")
      .style("color", function(d, i) {
        return colors(i);
      });


    // This is a way to specific particular colors for particular values:

    var color3 = d3.scale.ordinal().domain(['apples', 'blueberries', 'oranges', 'lemons']).range(['red', 'blue', 'orange', 'yellow']);

    var myFruit = ['apples', 'oranges', 'lemons', 'blueberries', 'lemons', 'oranges'];

    d3.select("#colorScale3")
    .selectAll("p")
    .data(myFruit)
    .enter()
    .append("p")
    .text(function(d) {
      return d;
    })
    .style("color", function (d) {
      return color3(d);
    });

</script>