使用Javascript和/或jQuery將每週數據轉換爲每月數據

Question

我有兩個相互關聯的數組。 Array A保存每週日期和Array B保存每週價格。每個星期五新數據都會通過API發佈並推送到這些數組中，因此有些月份有5個元素（即Jan），而有些月份只有4個元素（即2月份）。看下面的例子。

Array A：

["2003-01-03", "2003-01-10", "2003-01-17", "2003-01-24", "2003-01-31", "2003-02-07", "2003-02-14", "2003-02-21", "2003-02-28", etc..] 

Array B

["5.85", "5.95", "5.97", "5.91", "5.90", "5.88", "5.86", "5.84", "5.79", etc..] 

代碼：

var ajx = $.getJSON(api, function(data) {     
    for (var i =0; i <= data.count -1; i++){ 
     $("#table").append("<tr> <td>" + data.observations[i].date + "</td> <td>" + data.observations[i].value + "</td> </tr>"); 
     xaxis.push(data.observations[i].date) //Array A - weekly (default state) 
     yaxis.push(data.observations[i].value) //Array B - weekly (default state) 
     } 

我將如何能夠將它轉換爲 「月」 和 「年」 的陣列？

Answer 1

您可以使用array#reduce將基於年份的數據分組，每年可以對每個月的價格進行總結。

const arrayA = ["2003-01-03", "2003-01-10", "2003-01-17", "2003-01-24", "2003-01-31", "2003-02-07", "2003-02-14", "2003-02-21", "2003-02-28"], 
 
     arrayB = ["5.85", "5.95", "5.97", "5.91", "5.90", "5.88", "5.86", "5.84", "5.79"]; 
 

 
let result = arrayA.reduce(function(res, date, index){ 
 
    let [year, month, day] = date.split('-'); 
 
    let price = arrayB[index]; 
 
    if(year in res){ 
 
    if(month in res[year]) { 
 
     res[year][month].price = 
 
      ((res[year][month].price * res[year][month].count) + +price)/(res[year][month].count+1); 
 
     res[year][month].count += 1; 
 
     
 
    } else { 
 
     res[year][month] = {price : +price, count : 1}; 
 
    } 
 
    } else { 
 
    res[year] = {[month]: {price : +price, count :1}}; 
 
    } 
 
    return res; 
 
}, Object.create(null)); 
 

 
console.log(result);

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