javascript - 如何从随机数组对象创建关联数组？

Question

鉴于以下情况:

var dataSource = [
   {X: 0, Y: 0, ApiKey: "Something"},
   {X: 100, Y: 0, ApiKey: "Something"},
   {X: 1500, Y: 200, ApiKey: "Something"},
   {X: 1600, Y: 850, ApiKey: "Something"},
   {X: 0, Y: 750, ApiKey: "Something"},
   {X: 0, Y: 800, ApiKey: "Something"},
];

我需要创建一个新数组，从范围中指示发生了多少事件:

var result = [
  {fromX: 0, ToX: 500, incidence: 4},
  {fromX: 1500, ToX: 2000, incidence: 2}
];

我创建了一个迭代解决方案，问题是当数据源有 15000 个对象时需要 8-12 分钟!在 Node.js 中。有人知道更好的解决方案吗？

Answer 1

您可以给出一个间隔并使用哈希表计算间隔和计数。

var dataSource = [{ X: 0, Y: 0, ApiKey: "Something" }, { X: 100, Y: 0, ApiKey: "Something" }, { X: 1500, Y: 200, ApiKey: "Something" }, { X: 1600, Y: 850, ApiKey: "Something" }, { X: 0, Y: 750, ApiKey: "Something" }, { X: 0, Y: 800, ApiKey: "Something" }],
    interval = 500,
    grouped = [];
  
dataSource.forEach(function(a) {
    var key = Math.floor(a.X / interval);
    if (!this[key]) {
        this[key] = { fromX: key * interval, toX: (key + 1) * interval, incidence: 0 },
        grouped.push(this[key]);
    }
    this[key].incidence++;
}, Object.create(null));

console.log(grouped);

X 和 Y 的间隔。

var dataSource = [{ X: 0, Y: 0, ApiKey: "Something" }, { X: 100, Y: 0, ApiKey: "Something" }, { X: 1500, Y: 200, ApiKey: "Something" }, { X: 1600, Y: 850, ApiKey: "Something" }, { X: 0, Y: 750, ApiKey: "Something" }, { X: 0, Y: 800, ApiKey: "Something" }],
    interval = 500,
    grouped = [];
  
dataSource.forEach(function(a) {
    var keyX = Math.floor(a.X / interval),
        keyY = Math.floor(a.Y / interval),
        key = keyX + '|' + keyY;
    if (!this[key]) {
        this[key] = {
            fromX: keyX * interval,
            toX: (keyX + 1) * interval,
            fromY: keyY * interval,
            toY: (keyY + 1) * interval,
            incidence: 0
        },
        grouped.push(this[key]);
    }
    this[key].incidence++;
}, Object.create(null));

console.log(grouped);

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