Question

我有一个具有重复次数的数组。我想得到重复的次数。我的数组是这样的：

var array = [
    { asset: "A", sector: "Hospital" },
    { asset: "B", sector: "Hardware" },
    { asset: "C", sector: "Networking" },
    { asset: "D", sector: "Networking" },
    { asset: "E", sector: "Food" },
    { asset: "F", sector: "Hospital" },
    { asset: "G", sector: "Hardware" },
    { asset: "H", sector: "Industrial" },
    { asset: "I", sector: "Transport" },
    { asset: "J", sector: "Hardware" },
    { asset: "K", sector: "Networking" },
    { asset: "L", sector: "Transport" }
]

现在，我希望重复次数也按如下排序顺序进行计数：

final_array = [
    { sector: 'Hardware', count: 3 },
    { sector: 'Networking', count: 3 },
    { sector: 'Hospital', count: 2 },
    { sector: 'Transport', count: 2 },
    { sector: 'Food', count: 1 },
    { sector: 'Industrial', count: 1 }
]

我不知道从哪里可以知道这件事。我有很多链接，但是它们解决了数组下而不是对象数组上的重复。

我使用一种方法，但不能解决我的问题

var finalD = [];
c.forEach(x => {
    if (isSectorExists(x.sector, finalD) == true) {
        //Here I don't know how I will increase the counter.
    } else {
        finalD.push({ sector: x.sector, count: 1 });
    }
});

var isSectorExists = (sector, arr) => {
    return arr.some(function(el) {
        return el.sector === sector;
    });
};

我知道我的方法很长。是否有人拥有执行此类任务的最佳简便方法。真的很感谢任何帮助。在此先感谢

Answer 1

您可以构建一个以扇区名称作为键的对象counts，并以计数的形式存储计数的对象，遍历数组并更新这些计数，然后最终获得该counts对象的值

var array = [
      { asset: "A", sector: "Hospital" },
      { asset: "B", sector: "Hardware" },
      { asset: "C", sector: "Networking" },
      { asset: "D", sector: "Networking" },
      { asset: "E", sector: "Food" },
      { asset: "F", sector: "Hospital" },
      { asset: "G", sector: "Hardware" },
      { asset: "H", sector: "Industrial" },
      { asset: "I", sector: "Transport" },
      { asset: "J", sector: "Hardware" },
      { asset: "K", sector: "Networking" },
      { asset: "L", sector: "Transport" }
];
            
            
var counts = array.reduce((m, c) => {
    if (c.sector in m) m[c.sector].count += 1;
    else m[c.sector] = { sector: c.sector, count: 1};
    return m;
}, {});

let finalArray = Object.values(counts).sort((a, b) => b.count - a.count);

console.log(finalArray);

这将获得线性时间的计数（而不是为每个元素调用isSectorExists使其成为 O（n ^ 2）。

如何在javascript中的对象数组下获取值重复计数

1 个答案: