d3，js获取数组中对象的平均值

Question

我正在尝试获取此数据集中'min'列的平均值：

var data = [{
    name: "Site A",
    max: 202,
    min: 0,
    var: 202,
    x: 1,
    product: "Diesel",
    case: "Base Case"
  },
  {
    name: "Site B",
    max: 145,
    min: 147,
    var: -2,
    x: 0,
    product: "Diesel",
    case: "Base Case"
  },
  {
    name: "Site C",
    max: 221,
    min: 238,
    var: -17,
    x: 0,
    product: "Diesel",
    case: "Base Case"
  }]

您能告诉我我该怎么做吗？>

Answer 1

您可以使用d3.mean()，它以访问器函数作为第二个参数。该访问器函数将显示在数组中的每个对象中，并用于从中提取d3.mean()属性。

.min

看一下这个工作演示：

const average = d3.mean(data, d => d.min);

var data = [{
    name: "Site A",
    max: 202,
    min: 0,
    var: 202,
    x: 1,
    product: "Diesel",
    case: "Base Case"
  },
  {
    name: "Site B",
    max: 145,
    min: 147,
    var: -2,
    x: 0,
    product: "Diesel",
    case: "Base Case"
  },
  {
    name: "Site C",
    max: 221,
    min: 238,
    var: -17,
    x: 0,
    product: "Diesel",
    case: "Base Case"
  }];
  
const average = d3.mean(data, d => d.min);

console.log(average);