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javascript - 如何在 JavaScript / Jquery 中按数组分组

问题描述

我有一个数组如下

array1 = [{"month":"January","location":"CENTRAL","percentage":94},
{"month":"February","location":"CENTRAL","percentage":97},
{"month":"March","location":"CENTRAL","percentage":93},
{"month":"January","location":"NORTH","percentage":95},
{"month":"February","location":"NORTH","percentage":91},
{"month":"March","location":"NORTH","percentage":98}];

我想将我的数组格式化为如下所示

array2= [{
    location: "CENTRAL",
    January: 94,
    February: 97,
    March: 93},
    {
    location: "NORTH",
    January: 95,
    February: 91,
    March: 98}];

我尝试按如下功能使用分组

function groupBy(list, keyGetter) {
    const map = new Map();
    list.forEach((item) => {
        const key = keyGetter(item);
        if (!map.has(key)) {
            map.set(key, [item]);
        } else {
            map.get(key).push(item);
        }
    });
    return map;
}

const grouped = groupBy(array1, arr => arr.location);
console.log(grouped);

但我没有得到相同的格式。有什么建议请我在我的想法中缺少什么？非常感谢。

标签： javascriptjquery

解决方案

您可以通过移交组密钥、密钥的密钥和收集的值来使用动态方法。

然后将所有键/值对添加到对象中，稍后返回映射的值。

function groupBy(list, group, key, value) {
    return Array.from(list
        .reduce((map, object) => map.set(object[group], Object.assign(
            map.get(object[group]) || { [group]: object[group] },
            { [object[key]]: object[value] }
        )), new Map)
        .values()
    );
}

var array = [{ month: "January", location: "CENTRAL", percentage: 94 }, { month: "February", location: "CENTRAL", percentage: 97 }, { month: "March", location: "CENTRAL", percentage: 93 }, { month: "January", location: "NORTH", percentage: 95 }, { month: "February", location: "NORTH", percentage: 91 }, { month: "March", location: "NORTH", percentage: 98 }],
    result = groupBy(array, 'location', 'month', 'percentage');

console.log(result);
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