Question

我正在寻找一种有效的方法来计算元素的出现次数。我在循环中读取数据，并且在每个步骤中我都希望在结果数组中增加正确的对象元素，或者创建一个新对象元素（如果它尚不可用）。

我必须处理大量数据，所以我需要一个快速的解决方案。这是一个工作版本：

var hugeDataObject = [
    {id: '1234', dark: true},
    {id: '5678', dark: true},
    {id: '91011', dark: true},
    {id: '91011', dark: false}
];
var ids = [];
var darks = [];
var allIds = [];
var allDarks = [];
  hugeDataObject.forEach(function(attrs) {
    var index = allIds.indexOf(attrs.id);
    if(index >= 0) ids[index].amount += 1;
    else {
      ids.push({type: attrs.id, amount: 1}); 
      allIds.push(attrs.id);
    }

    var index = allDarks.indexOf(attrs.dark);
    if(index >= 0) darks[index].amount += 1;
    else {
      darks.push({type: attrs.dark, amount: 1}); 
      allDarks.push(attrs.dark);
    }
  });

Fiddle 但我有更多的类型，我需要计算，所以变量太多了。

结果：

ids = [
  {type: '1234', amount: 1},
  {type: '5678', amount: 1},
  {type: '91011', amount: 2}
]

darks = [
  {type: true, amount: 3},
  {type: false, amount: 1}
]

（如果你使用loDash，没关系）

提前致谢！

Answer 1

如何存储更简单的结构：

var objects = {};
objects['id1234'] = 384;
objects['id5678'] = 955;
objects['id91011'] = 1510;

/* increment */
objects['id1234']++;

Answer 2

var counter = {};
hugeDataObject.forEach(function(attrs) {
    if (counter[attrs.id]) {
        counter[attrs.id]++;
    }
    else {
        counter[attrs.id] = 1;
    }
});

或者如果你需要数组：

var counts = [];
var indexMap = {};

var i = 0;
indexMap[0] = -1;

hugeDataObject.forEach(function(attrs) {

    var index = indexMap[attrs.id];

    if (index == undefined) {
        indexMap[attrs.id] = i;
        counts[i] = { id: attrs.id, amount: 1 };
        i++;
    }
    else {
        var existingCounter = counts[index];
        existingCounter.amount++;
    }
});

Answer 3

如果我理解你的观点，那么你试试这个：

 var ids = [];
  var allIds = [];
  hugeDataObject.forEach(function(attrs) {
    var index = allIds.indexOf(attrs.id);
    if(index >= 0){
      ids[index].amount = ids[index].amount + 1;

    } else {
      ids.push({type: attrs.id, amount: 1}); 
      allIds.push(attrs.id);
      // Here first should check is this type available, 
      // after create it or increase the amount
    }
  });

  console.log(ids);

Answer 4

这不是太简单，但我明白了。

var getObjectBy = function(base, id, array) {
    for (var i = 0, len = array.length; i < len; i++) {
        if (array[i][base] === id) return array[i];
    }
    return null;
};

var hugeDataObject = [
    {id: '1234', dark: true},
    {id: '5678', dark: true},
    {id: '91011', dark: true},
    {id: '91011', dark: false}
];
var ids = [];
var darks = [];
hugeDataObject.forEach(function(attrs) {
    var index = getObjectBy('type', attrs.id, ids);
    if (index === null) ids.push({type: attrs.id, amount: 1});
    else index.amount += 1;

    var index = getObjectBy('type', attrs.dark, darks);
    if (index === null) darks.push({type: attrs.dark, amount: 1});
    else index.amount += 1;
});

Updated Fiddle

也许它不太漂亮，但我觉得有效。如果你知道更好的方法，那就写下来吧，我会接受的！

谢谢你的答案！

将事件存储在数组中

4 个答案: