如何在 JavaScript 中动态填充多维数组？

Posted 2023-02-14

【中文标题】如何在 JavaScript 中动态填充多维数组？

【英文标题】：How to dynamically populate a multidimensional array in JavaScript?

【发布时间】：2020-09-27 23:14:57

【问题描述】：

我有一个从 URL 请求中获得的对象：

var data = 
    "DataSet": 
      "Series": [
     
      "@FREQ": "A",
      "@REF_AREA": "BF",
      "@INDICATOR": "NGDP_R_PC_PP_PT",
      "@UNIT_MULT": "0",
      "@TIME_FORMAT": "P1Y",
      "Obs": [
        
          "@TIME_PERIOD": "2018",
          "@OBS_VALUE": "6"
        ,
        
          "@TIME_PERIOD": "2019",
          "@OBS_VALUE": "5"
        ,
        
          "@TIME_PERIOD": "2020",
          "@OBS_VALUE": "1"
        ,
        
          "@TIME_PERIOD": "2021",
          "@OBS_VALUE": "5"
        
      ]
    ,
    
      "@FREQ": "A",
      "@REF_AREA": "CI",
      "@INDICATOR": "NGDP_R_PC_PP_PT",
      "@UNIT_MULT": "0",
      "@TIME_FORMAT": "P1Y",
      "Obs": [
        
          "@TIME_PERIOD": "2018",
          "@OBS_VALUE": "6"
        ,
        
          "@TIME_PERIOD": "2019",
          "@OBS_VALUE": "6"
        ,
        
          "@TIME_PERIOD": "2020",
          "@OBS_VALUE": "2"
        ,
        
          "@TIME_PERIOD": "2021",
          "@OBS_VALUE": "8"
        
      ]
    
  ]

我想要一个看起来像这样的数组，每个“Obs”数组中的每个年份和值都在它自己的数组中：

var dataSet = [
[["2018","6"],["2019","5"],["2020","1"],["2021","5"]],
[["2018","6"],["2019","6"],["2020","2"],["2021","8"]]
]

我试过这个：

let dataO = []  
var dataSet = data.Series.map((x,index) =>                   
  dataO.push(x.Obs.map(i=>i['@TIME_PERIOD']))
  dataO.push(x.Obs.map(r=>r['@OBS_VALUE']))
  return dataO
)

但我得到了一个包含 2 个元素的数组，每个元素都包含来自对象的所有数据。我看不出哪里出错了。任何帮助表示赞赏。谢谢！

【参考方案1】：

简单的双循环：

var dataSet = [];
data.DataSet.Series.map((x) => 
      var periods = [];
      x.Obs.map((y) => 
          periods.push([y['@TIME_PERIOD'], y['@OBS_VALUE']]);
      ); 

      dataSet.push(periods);
);

可在下面测试：

var data = 
  "DataSet": 
    "Series": [
        "@FREQ": "A",
        "@REF_AREA": "BF",
        "@INDICATOR": "NGDP_R_PC_PP_PT",
        "@UNIT_MULT": "0",
        "@TIME_FORMAT": "P1Y",
        "Obs": [
            "@TIME_PERIOD": "2018",
            "@OBS_VALUE": "6"
          ,
          
            "@TIME_PERIOD": "2019",
            "@OBS_VALUE": "5"
          ,
          
            "@TIME_PERIOD": "2020",
            "@OBS_VALUE": "1"
          ,
          
            "@TIME_PERIOD": "2021",
            "@OBS_VALUE": "5"
          
        ]
      ,
      
        "@FREQ": "A",
        "@REF_AREA": "CI",
        "@INDICATOR": "NGDP_R_PC_PP_PT",
        "@UNIT_MULT": "0",
        "@TIME_FORMAT": "P1Y",
        "Obs": [
            "@TIME_PERIOD": "2018",
            "@OBS_VALUE": "6"
          ,
          
            "@TIME_PERIOD": "2019",
            "@OBS_VALUE": "6"
          ,
          
            "@TIME_PERIOD": "2020",
            "@OBS_VALUE": "2"
          ,
          
            "@TIME_PERIOD": "2021",
            "@OBS_VALUE": "8"
          
        ]
      
    ]
  
;

var dataSet = [];
data.DataSet.Series.map((x) => 
      var periods = [];
      x.Obs.map((y) => 
          periods.push([y['@TIME_PERIOD'], y['@OBS_VALUE']]);
      ); 

      dataSet.push(periods);
);

console.log(dataSet);

【参考方案2】：

你可以使用flatMap:

data.DataSet.Series
    .flatMap(x => x.Obs)
    .map(x => [x["@TIME_PERIOD"], x["@OBS_VALUE"]])

【讨论】：

谢谢，但这提供了一个包含所有值的数组。虽然很高兴了解 flatMap()，但我可以充分利用它。