javascript - 如何使用 D3 制作三重条形图？

Question

下面的代码工作得很好，但我想使用另一个数据集。属性本身就是数组的数据集。它们的结构如下:[年份、人口、男性、女性]。年份将是 X 轴，其他三个轴将显示为彼此相邻的条形。如何制作三重条形图？从哪里开始？

    <script type="text/javascript">
        //Width and height
        var w = 500;
        var h = 250;
        var barPadding = 5;

        //Dataset
        var dataset = [10027, 10200, 10328, 10436, 10551, 10680, 10822, 10957, 11096, 11278,
                        11417, 11556, 11721, 11890 ];

        //The other dataset
        //[year, population, man, woman]
        //var dataset = [[1950, 10027, 4998, 5029], [1950, 10027, 4998, 5029], [1950, 10027, 4998, 5029], etc];

        //Scale
        var x = d3.scale.ordinal().range([0, w])
        var y = d3.scale.linear().range([h, 0]);

        // Axis
        var xAxis = d3.svg.axis()
            .scale(x)
            .orient("bottom")

        var yAxis = d3.svg.axis()
            .scale(y)
            .orient("left")
            .ticks(10);

        //Create SVG element
        var svg = d3.select("body")
                    .append("svg")
                    .attr("width", w)
                    .attr("height", h);

        svg.selectAll("rect")
           .data(dataset)
           .enter()
           .append("rect")
           .attr("x", function(d, i) {
                return i * (w / dataset.length);
           })
           .attr("y", function(d) {
                return h - (d / 50);
           })
           .attr("width", w / dataset.length - barPadding)
           .attr("height", function(d) {
                return d / 50;
           })
           .attr("fill", function(d) {
                return "rgb(102, 0, 51)";
           });

            svg.append("g")
                .attr("class", "x axis")
                .attr("transform", "translate(0," + h + ")")
                .call(xAxis)
                .style("text-anchor", "end")
                .text("Years");

            svg.append("g")
                .attr("class", "y axis")
                .call(yAxis)
                .append("text")
                .attr("transform", "rotate(-90)")
                .attr("y", 6)
                .attr("dy", "0.5em")
                .style("text-anchor", "end")
                .text("Population in millions");

    </script>

(小问题:为什么我的x轴没有出现？)

提前致谢

Answer 1

针对你的小问题:你的 x 轴和 y 轴被渲染，但在 svg 可见空间之外。处理此问题的常见方法是在 svg 内添加 margin 并使用边距内的 width 和 height 渲染图表。 D3 的作者将其描述为 conventional margin

我用你所说的三重条形图创建了一个片段。此代码是 grouped barchart Bostock 应用于您的数据集。我稍微更改了数据集，以便每年都是一个具有属性 population、men、women 和 year< 的对象。通过此设置，可以更轻松地处理这些值。

分组条形图代码背后的想法是为数据集中的每个对象添加一个组元素，并渲染该组内的条形。因此，您将数据集绑定(bind)到年份组。在年份选择中，每个元素都绑定(bind)到数据集数组中的相应对象。如果这一切对您来说没有多大意义，也许您应该阅读 Let's make a Bar Chart Bostock 的教程。他们对基本步骤进行了很好的概述；)

var dataset = [{year:1950, population:10000, men:4500, women:5500}, {year:1951, population:10200, men:5000, women:6200}, {year:1952, population:11000, men:6000, women:5000}, {year:1953, population:12000, men:5900, women:6100}];

  // setup conventional margin, see http://bl.ocks.org/mbostock/3019563
  var margin = {top: 20, right: 30, bottom: 30, left: 60},
      width = 700 - margin.left - margin.right,
      height = 400 - margin.top - margin.bottom;

  // accessor functions for the 4 values
  var year = function(d) { return d.year; };
  var population = function(d) { return d.population; };
  var men = function(d) { return d.men; };
  var women = function(d) { return d.women; };
  var valueObject = function(d) { return [{name:"population", value:population(d)},{name:"men", value: men(d)}, {name: "women", value: women(d)}]; };

  var color = d3.scale.ordinal()
    .domain(["population","men","women"])
    .range(["#31a354","#3182bd","#e6550d"]);

  var x0 = d3.scale.ordinal()
      .rangeRoundBands([0, width], .2)
      .domain(dataset.map(year)); // use the year for the xAxis

  var x1 = d3.scale.ordinal()
      .domain(["population","men","women"])
      .rangeRoundBands([0, x0.rangeBand()]);

  var y = d3.scale.linear()
      .range([height, 0])
      .domain([0, d3.max(dataset.map(population))]); // use the population for calculating the maximum value
  
  var xAxis = d3.svg.axis()
      .scale(x0)
      .orient("bottom");
  
  var yAxis = d3.svg.axis()
      .scale(y)
      .orient("left");
  
  var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
    .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

  svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Population");

  var years = svg.selectAll(".year")
      .data(dataset)
      .enter()
    .append("g")
      .attr("class", "year")
      .attr("transform", function(d) { return "translate(" + x0(year(d)) + ",0)"; });

  years.selectAll("rect")
      .data(valueObject)
      .enter()
    .append("rect")
      .attr("width", x1.rangeBand())
      .attr("x", function(d) { return x1(d.name); })
      .attr("y", function(d) { return y(d.value); })
      .attr("height", function(d) { return height - y(d.value); })
      .attr("fill", function(d) { return color(d.name); });

  var legend = svg.selectAll(".legend")
      .data(["population","men","women"])
    .enter().append("g")
      .attr("class", "legend")
      .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });

  legend.append("rect")
      .attr("x", width - 18)
      .attr("width", 18)
      .attr("height", 18)
      .style("fill", color);

  legend.append("text")
      .attr("x", width - 24)
      .attr("y", 9)
      .attr("dy", ".35em")
      .style("text-anchor", "end")
      .text(function(d) { return d; });

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>