javascript - 使用 lodash 将对象数组排序为 Top N，其中 n+1 为 "others"

Question

假设我有这个数据结构，示例输入:

[ {name: "a", val:1},
  {name: "b", val:2},
  {name: "c", val:3},
  {name: "d", val:4},
  {name: "e", val:5},
  {name: "f", val:1},
  {name: "g", val:2},
  {name: "h", val:1},
]

我想输出 2 个数组:

首先是对象的 val 属性，首先是最高(最高)值，然后是剩余元素的总和。如果我们假设 n=5，作为前 5 个结果 +“其余”。所以 array[5] 上的这个数组 = 所有不在前 5 名中的 val 属性的总和。示例输出:

[2,3,4,5,2,3]

第二个数组将是与前 5 个对应的名称属性，其中 array[5] = "others"，或其他一些任意字符串。示例输出:

["b","c","d","e","g","others"]

如何使用 lodash 以最大效率和/或最大代码清晰度来实现这一点？ lodash

编辑:示例代码:

       var n = 5;
  var input = [ 
      {name: "a", val:1},
      {name: "b", val:2},
      {name: "c", val:3},
      {name: "d", val:4},
      {name: "e", val:5},
      {name: "f", val:1},
      {name: "g", val:2},
      {name: "h", val:1},
    ];
    var sortedArray = _.sortByOrder(input, ['val'], [false]);
    var topNValues = _.pluck(_.slice(sortedArray, 0, n), 'val');
    var restValues = _.pluck(_.slice(sortedArray, n, sortedArray.length), 'val');
    var restAdded = _.reduce(restValues, function(i, j) {
    return i + j;
}, 0); 
    topNValues.splice(n, 0,restAdded);
    $scope.array1 = topNValues; 
    var names = _.pluck(_.slice(sortedArray, 0, n), 'name');
    names.splice(n,0,"others");
    $scope.array2 = names;

一定有比我的 jsfiddle 更干净的链接方式:http://jsfiddle.net/u1w4da6r/2/

Answer 1

所以它不是单链，但看起来相当容易阅读。我没有进行任何性能测试，但易于理解可能应该是您的主要目标。

Codepen

function groupOthers (obj, n) {
  var indicesToKeep = _.chain(obj)
    .map(function (item, index) { //zip each item with its index
      return {item: item, index: index}
    })
    .sortBy(function (zipped) { //sort by the val (highest to lowest)
      return -zipped.item.val
    })
    .take(n) //take the top 5
    .map('index') // we only care about the indices
    .value()

  var partitioned = _.partition(obj, function (item, index) {
    return _.includes(indicesToKeep, index)
  })

  var finalObjJoined = partitioned[0].concat({
    name: 'others',
    val: _.sum(partitioned[1], 'val')
  })

  return [_.map(finalObjJoined, 'name'), _.map(finalObjJoined, 'val')]
}

console.log(groupOthers(x, 5))