如何使用underscorejs分组并获得平均值 [英] How to groupby and get average using underscorejs

问题描述

如何按category分组并使用下划线求平均值?

How to groupBy category and get the average using underscore?

我有一个对象数组.它应该按 category 分组，Analytics 的平均值是根据 val 属性计算的，即 1+2 => 3. 3/total类别的数量.所以，3/2 => 1.5

I have an array of objects. It should be grouped by category and average for Analytics is calculated from the val property ie., 1+2 => 3. 3/total number of categories. So, 3/2 => 1.5

预期输出:{ 分析:1.5 }

[{
  area:"Digital",
  category:"Analytics",
  qId:"wRHmpHHGzrYLsCEJ3",
  type:"Reorganize",
  userId:"M4JEJGiPZ8e9om9A",
  val:1
},
{
  area:"Digital",
  category:"Analytics",
  qId:"wRHmpHHGzrYLsCEJ3",
  type:"Reorganize",
  userId:"M4JEJGiPZ8e9om9A",
  val:2
}]

谢谢

推荐答案

您可以按类别对对象进行分组，然后遍历这个结果对象中的所有键和减少值:

var types = _.groupBy(array, 'category');
var result = _.mapObject(types, function(val, key) {
  return _.reduce(val, function(memo, v) { 
    return memo + v.val; 
  }, 0) / val.length;
});

var array = [{
  area:"Digital",
  category:"Analytics",
  qId:"wRHmpHHGzrYLsCEJ3",
  type:"Reorganize",
  userId:"M4JEJGiPZ8e9om9A",
  val:1
},
{
  area:"Digital",
  category:"Analytics",
  qId:"wRHmpHHGzrYLsCEJ3",
  type:"Reorganize",
  userId:"M4JEJGiPZ8e9om9A",
  val:2
}];

var types = _.groupBy(array, 'category');
var result = _.mapObject(types, function(val, key) {
  return _.reduce(val, function(memo, v) { 
    return memo + v.val; 
  }, 0) / val.length;
});

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>

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