使用JavaScript在二维数组中添加值

y2knoproblem

我想合并并添加以下2D数组：

var arr = [
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TEN", 10],
    ["FIVE", 5],
    ["ONE", 1],
    ["QUARTER", 0.25],
    ["QUARTER", 0.25],
    ["DIME", 0.1],
    ["DIME", 0.1],
    ["PENNY", 0.01],
    ["PENNY", 0.01],
    ["PENNY", 0.01],
    ["PENNY", 0.01]
    ];

生成的二维数组如下所示：

 arr = [
     ["TWENTY", 80],
     ["TEN", 10],
     ["FIVE", 5],
     ["QUARTER", 0.50],
     ["DIME", 0.20],
     ["PENNY", 0.04]
     ];

基本上，我是将数字值加起来并压缩字符串值。我尝试了map，reduce和for循环，但是这一步让我很困惑。

空灵的

您真正需要的只是一个reduce和一个map，这可能会成为一个很好的MapReduce笑话。

var arr = [
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TWENTY", 20],
    ["TEN", 10],
    ["FIVE", 5],
    ["ONE", 1],
    ["QUARTER", 0.25],
    ["QUARTER", 0.25],
    ["DIME", 0.1],
    ["DIME", 0.1],
    ["PENNY", 0.01],
    ["PENNY", 0.01],
    ["PENNY", 0.01],
    ["PENNY", 0.01]
];
var obj = arr.reduce(function (out, el) {
    out[el[0]] = (out[el[0]] || 0) + el[1];
    return out;
}, {});
var out = Object.keys(obj).map(function (key) {
    return [key, obj[key]]
}); //[["TWENTY",80],["TEN",10],["FIVE",5],["ONE",1],["QUARTER",0.5],["DIME",0.2],["PENNY",0.04]]

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