topical media & game development

topical media & game development

[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

mobile-data-circle-06.htm / htm


  <script src="http://d3js.org/d3.v3.min.js"></script>
  <link rel="stylesheet" type="text/css" href="mobile-data-circle-style-d3.css">
  <script type="text/javascript">

data


    var data = [32, 57, 112],
        dataEnter = data.concat(293),
        dataExit = data.slice(0, 2),
        w = 360,
        h = 180,
        x = d3.scale.ordinal().domain([57, 32, 112]).rangePoints([0, w], 1),
        y = d3.scale.ordinal().domain(data).rangePoints([0, h], 2);

</script> <p>There’s a second argument to each function you can use: it specifies the <em>index</em> of the element within its selection. This is a <a href="http://en.wikipedia.org/wiki/Zero-based_numbering">zero-based</a> index, and it’s useful for computing offsets or as a simple way of identifying individual elements. The argument is optional; if you don’t specify it when declaring your function, it will be ignored. For example:</p> <div class="chart" id="chart-6b"> <pre class="code">circle.attr("cx", function(d, i) { return i * 100 + 30; }); </pre> <button>run</button>  </div> <script type="text/javascript">

script


  (function() {
    var svg = d3.select("#chart-6b").append("svg")
        .attr("width", w)
        .attr("height", h);

select


    var g = svg.selectAll("g")
        .data(data)
      .enter().append("g")
        .attr("transform", function(d) { return "translate(" + x(d) + "," + y(d) + ")"; });
  
    g.append("circle")
        .attr("class", "little")
        .attr("r", 12);
  
    g.append("text")
        .attr("dy", ".35em")
        .attr("text-anchor", "middle")
        .text(function(d, i) { return i; });

button


    d3.select("#chart-6b button").on("click", function() {
      g.attr("transform", function(d) { return "translate(" + x(d) + "," + y(d) + ")"; })
        .transition()
          .duration(750)
          .attr("transform", function(d, i) {
           return "translate(" + (i * 100 + 30) + "," + y(d) + ")"; }
          );
    });
  })();

</script> <p>Here we use the index <em>i</em> to position the elements sequentially only the <em>x</em>-dimension. Each element is separated by 100 pixels, with an offset of 30 pixels from the left side. In SVG, the origin is in the top-left corner.</p>

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