Lodash。如何从数组对象中获取聚合数组

你可以使用Lodash库的groupBy和map函数来从数组对象中获取聚合数组。下面是一个示例代码：

const _ = require('lodash');

const data = [
  { name: 'John', age: 30, department: 'IT' },
  { name: 'Jane', age: 25, department: 'HR' },
  { name: 'Bob', age: 35, department: 'IT' },
  { name: 'Alice', age: 28, department: 'HR' },
  { name: 'David', age: 33, department: 'IT' }
];

// 使用groupBy函数按照department属性进行分组
const groupedData = _.groupBy(data, 'department');

// 使用map函数将分组后的对象数组转换为聚合数组
const aggregatedData = _.map(groupedData, (group, key) => {
  // 计算每个分组的年龄平均值
  const averageAge = _.meanBy(group, 'age');

  // 返回聚合结果对象
  return {
    department: key,
    count: group.length,
    averageAge: averageAge
  };
});

console.log(aggregatedData);

运行上述代码，你将会得到一个聚合数组，其中每个元素包含部门名称、人数和平均年龄。输出结果应为：

[
  { department: 'IT', count: 3, averageAge: 32.67 },
  { department: 'HR', count: 2, averageAge: 26.5 }
]