如何使用underscore.js分組並獲得平均值

Question

如何對category進行分組並使用下划線獲得平均值？

我有一個對象數組。 它應該按category分組，並且Analytics平均值是從val屬性計算得出的，即1 + 2 =>3。3 /類別總數。 所以3/2 => 1.5

預期輸出： { Analytics: 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
}]

謝謝

Answer 1

您可以按類別對對象進行分組 ，然后遍歷此結果對象中的所有鍵並減少值 ：

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); 

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