How to dynamically populate a multidimensional array in JavaScript?

Question

I have an object that I get from a URL request:

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"
        }
      ]
    }
  ]
}

} And I want an array that looks like this, each of the years and values from each 'Obs' array in its own array:

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

I have tried this:

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
})

But I get an array with 2 elements, each containing all of the data from the object. I can't see where I am going wrong. Any help is appreciated. Thanks!

Ed Lucas · Accepted Answer · 2020-06-08 22:07:15Z

Simple double loop:

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

      dataSet.push(periods);
});

Testable below:

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);

Salem · Accepted Answer · 2020-06-08 21:48:45Z

1

You can use flatMap:

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

answered Jun 8, 2020 at 21:48

Salem

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1 Comment

Ajay Ubhi Over a year ago

Thanks but this gave one array with all the values in. Although great to know about flatMap(), I can make use of that a lot.

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