转换JavaScript Array，创建表格视图

Question

我已经通过类似的问题进行了搜索，并试图自行解决这个问题，但是我的编程技巧很薄弱。

我有这样一个数组：

[{"city": "Amsterdam", "year": "2013", "amount": "450"}, 
{"city": "Rotterdam", "year": "2013", "amount": "620"}, 
{"city": "Geneva", "year": "2014", "amount": "530"}, 
{"city": "Rotterdam", "year": "2015", "amount": "350"}] 

，我想用“城市”和“年”获得“量”来改变它。例如。鹿特丹：[620，N/A，350]。 “不适用”，因为2014年的价值缺失。 我正在检查地图功能等，但我的技能很弱。最后我想创建一个有年份（水平）和城市（垂直）的表格视图。 请指教。谢谢

Answer 1

我不认为这是编程技能，但算法技能。下面是一个代码做你想要什么：

var amounts = [{"city": "Amsterdam", "year": "2013", "amount": "450"},{"city": "Rotterdam", "year": "2013", "amount": "620"},{"city": "Geneva", "year": "2014", "amount": "530"},{"city": "Rotterdam", "year": "2015", "amount": "350"}], 
 
    formattedAmounts = {} 
 
; 
 
       
 
for (var i = 0; i < amounts.length; i++) { 
 
    var amount = amounts[i]; 
 
    
 
    if (undefined === formattedAmounts[amount.city]) { 
 
     formattedAmounts[amount.city] = {}; 
 
    } 
 

 
    formattedAmounts[amount.city][amount.year] = amount.amount; 
 
} 
 

 
console.log(JSON.stringify(formattedAmounts)); 
 
alert(JSON.stringify(formattedAmounts)); 
 

 
function getCityAmount(city) { 
 
    var years = [2013, 2014, 2015], 
 
     cityAmounts = [] 
 
    ; 
 

 
    for (var i = 0; i < years.length; i++) { 
 
     cityAmounts.push(
 
      formattedAmounts[city] && formattedAmounts[city][years[i]] 
 
       ? formattedAmounts[city][years[i]] 
 
       : 'N/A' 
 
     ); 
 
    } 
 

 
    return cityAmounts; 
 
} 
 

 
console.log(JSON.stringify(getCityAmount('Amsterdam'))); 
 
alert(JSON.stringify(getCityAmount('Amsterdam'))); 
 

 
function getCitiesAmounts() { 
 
    var citiesAmounts = []; 
 

 
    for (var i = 0; i < amounts.length; i++) { 
 
     citiesAmounts.push(getCityAmount(amounts[i].city)); 
 
    } 
 

 
    return citiesAmounts; 
 
} 
 

 
console.log(JSON.stringify(getCitiesAmounts())); 
 
alert(JSON.stringify(getCitiesAmounts()));