使用 DC.js 从饼图中获取选定的切片颜色

Question

我有一个协调的饼图和条形图。我的饼图包含年份列表，我的条形图包含每年的信息。当我在饼图中单击一年时，条形图会显示该年的相关详细信息。

场景 需要在饼图切片单击时将条形颜色更改为饼图中选定的切片颜色。

请指教。

Answer 1

首先为你的条形图和饼图设置一个通用的色标

pieChart
    .colors(d3.scale.category10())
    ...

和

barChart
    .colors(d3.scale.category10())
    ...

请注意，您可能需要根据您拥有的值的数量选择不同的值。

然后，为条形图设置 colorAccessor 以便它根据与每个条形对应的饼图索引选择一个索引。如果您可以访问所有唯一的 pieValues（您可以在 pie 组上使用 .all() 和 .map() 轻松获得。类似

var pieValues = year_total.all().map(function(d) { return d.key });

其中 year_total 是饼图维度的组。

假设您有可用的基础数据，使用类似的方法很容易获得正确的索引

.colorAccessor(function(d, i){ return years.indexOf(data[i].Year); })

仅此而已！

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小提琴 - http://jsfiddle.net/r8yern6o/

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基本代码改编自 http://www.codeproject.com/Articles/697043/Making-Dashboards-with-Dc-js-Part-2-Graphing 的优秀教程（链接到 https://github.com/dc-js/dc.js/wiki > 书籍和教程部分）

为了后代，假设您已包含所有库

JS

var barChart  = dc.barChart("#chart-line-hitsperday");

var data = [
    {date: "12/27/2012", http_404: 2, http_200: 190, http_302: 100},
    {date: "12/28/2012", http_404: 2, http_200: 10, http_302: 100},
    {date: "12/29/2012", http_404: 1, http_200: 300, http_302: 200},
    {date: "12/30/2012", http_404: 2, http_200: 90, http_302: 0},
    {date: "12/31/2012", http_404: 2, http_200: 90, http_302: 0},
    {date: "01/01/2013", http_404: 2, http_200: 90, http_302: 0},
    {date: "01/02/2013", http_404: 1, http_200: 10, http_302: 1},
    {date: "01/03/2013", http_404: 2, http_200: 90, http_302: 0},
    {date: "01/04/2013", http_404: 2, http_200: 90, http_302: 0},
    {date: "01/05/2013", http_404: 2, http_200: 90, http_302: 0},
    {date: "01/06/2013", http_404: 2, http_200: 200, http_302: 1},
    {date: "01/07/2013", http_404: 1, http_200: 200, http_302: 100}
];
var ndx = crossfilter(data);
var parseDate = d3.time.format("%m/%d/%Y").parse;
data.forEach(function(d) {
    d.date = parseDate(d.date);
    d.total= d.http_404+d.http_200+d.http_302;
    d.Year=d.date.getFullYear();
});

var dateDim = ndx.dimension(function(d) {return d.date;});
var hits = dateDim.group().reduceSum(function(d) {return d.total;});
var minDate = dateDim.bottom(1)[0].date;
var maxDate = dateDim.top(1)[0].date;

var pieChart = dc.pieChart("#chart-ring-year");
var yearDim  = ndx.dimension(function(d) {return +d.Year;});
var year_total = yearDim.group().reduceSum(function(d) {return d.http_200+d.http_302;});
var pieValues = year_total.all().map(function(d) { return d.key });

barChart
    .colors(d3.scale.category10())
    .width(500).height(200)
    .dimension(dateDim)
    .group(hits)
    .x(d3.time.scale().domain([minDate,maxDate]))
    .brushOn(false)
    .xUnits(d3.time.days)
    .colorAccessor(function(d, i){ return pieValues.indexOf(data[i].Year); })
    .yAxisLabel("Hits per day");

pieChart
    .colors(d3.scale.category10())
    .width(150).height(150)
    .dimension(yearDim)
    .group(year_total)
    .innerRadius(30);

dc.renderAll();

HTML

<div id="chart-ring-year"></div>
<div id="chart-line-hitsperday"></div>