需要在一組物件中將物件分組

我有下一個資料：

const data = [
    {amount: 100, percent: 1, days: 7},
    {amount: 75, percent: 3, days: 8},
    {amount: 75, percent: 3, days: 3},
    {amount: 100, percent: 2, days: 5},
    {amount: 100, percent: 1, days: 10},
    {amount: 50, percent: 3, days: 9}
];

任務是按數量和百分比對物件進行分組，以便如果不同物件中的數量和百分比相同，我需要添加它們的天數。結果應該如下所示：

const data = [
    {amount: 100, percent: 1, days: 17},
    {amount: 75, percent: 3, days: 11},
    {amount: 100, percent: 2, days: 5},
    {amount: 50, percent: 3, days: 9}
];

由于百分比不同，第 1 個和第 3 個物件未分組。我曾嘗試使用 reduce 方法：

const result = data.reduce((groupedByAmount, current) => {
    let amount = current.amount;
    let percent= current.percent;
    if (amount == amount && percent == percent) {
        groupedByAmount.amount = amount;
        current.days  = current.days
    }
    return groupedByAmount
}, {
    amount: 0,
    percent: null,
    days: 0
});

我不知道如何檢查金額和百分比是否相同，也許地圖或過濾器會有所幫助

uj5u.com熱心網友回復：

考慮到您建議的每種方法：

• reduce=> 將陣列元素減少為單個值。可用于創建一個物件，然后將該物件轉換回陣列

• map=> 為陣列中的每個值回傳一個值

• filter=> 回傳多個（或單個）匹配值

您可以遍歷每個值，構建一個新陣列并使用它filter()來查找要添加的現有值。

注意：由于多次使用.filter()- 使用復合鍵（將兩個值組合成一個值）可??能會更好地執行，這可能不會在大型陣列中表現良好。

const data = [
    {amount: 100, percent: 1, days: 7},
    {amount: 75, percent: 3, days: 8},
    {amount: 75, percent: 3, days: 3},
    {amount: 100, percent: 2, days: 5},
    {amount: 100, percent: 1, days: 10},
    {amount: 50, percent: 3, days: 9}
];

var result = [];

data.forEach(e => {
    var current = result.filter(d => d.amount == e.amount && d.percent == e.percent);
    if (current.length === 0) {
        result.push(e);
    } else {
        current[0].days  = e.days;
    }
});
console.log(result);

uj5u.com熱心網友回復：

const data = [
    {amount: 100, percent: 1, days: 7},
    {amount: 75, percent: 3, days: 8},
    {amount: 75, percent: 3, days: 3},
    {amount: 100, percent: 2, days: 5},
    {amount: 100, percent: 1, days: 10},
    {amount: 50, percent: 3, days: 9}
];

const doGroup = (data) => {
    const obj = data.reduce((result, next) => {
    const key = `${next.amount}_${next.percent}`
    const dd =  result[key]?.days ?? 0;
    result[key] = {...next, days: next.days   dd};
    return result;
  }, {});
  return Object.values(obj);
}

console.log(doGroup(data))

uj5u.com熱心網友回復：

const data = [
    {amount: 100, percent: 1, days: 7},
    {amount: 75, percent: 3, days: 8},
    {amount: 75, percent: 3, days: 3},
    {amount: 100, percent: 2, days: 5},
    {amount: 100, percent: 1, days: 10},
    {amount: 50, percent: 3, days: 9}
];

const temp = data.reduce((acc, {amount, percent, days}) => {
  acc[amount] ||= {}
  acc[amount][percent] ||= 0
  acc[amount][percent]  = days
  return acc;
}
,{});

const result = Object.entries(temp).reduce((acc, [amount, obj]) => {
  acc.push(...Object.entries(obj).map(([percent, days]) => ({ amount: Number(amount), percent: Number(percent), days })))
  return acc
},[])

console.log(result)

uj5u.com熱心網友回復：

這個例子的行數更多，但也許更簡單。

const data = [
  {amount: 100, percent: 1, days: 7},
  {amount: 75, percent: 3, days: 8},
  {amount: 75, percent: 3, days: 3},
  {amount: 100, percent: 2, days: 5},
  {amount: 100, percent: 1, days: 10},
  {amount: 50, percent: 3, days: 9}
];

function group_by_amount_percent(array) {
  var ret = []
  var cache = {}
  array.forEach(function(e, i, a) {
    if (cache[e.amount] == null) { cache[e.amount] = {} }
    if (cache[e.amount][e.percent] == null) { cache[e.amount][e.percent] = 0 }
    cache[e.amount][e.percent]  = e.days
  })
  for (var amount in cache) {
    for (var percent in cache[amount]) {
      ret.push({amount: amount, percent: percent, days: cache[amount][percent]})
    }
  }
  return ret
}

console.log('group_by_amount_percent(data): ', group_by_amount_percent(data))

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