javascript - 迭代一个对象并平均一些值

Question

我有一个像这样的数据结构allDataJson:

[ { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'POL',
    coverage: 95.13 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'DIPH',
    coverage: 95.14 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'TET',
    coverage: 95.44 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'PER',
    coverage: 95.12 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'EP B',
    coverage: 94.72 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'HIB',
    coverage: 94.33 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'MEASLES',
    coverage: 91.06 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'MUMPS',
    coverage: 91.06 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'RUB',
    coverage: 91.06 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'VAR',
    coverage: 1.86 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men C',
    coverage: 89.33 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'PNC',
    coverage: 91.84 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'EP A',
    coverage: 0.87 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'ROTA',
    coverage: 6.39 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men B',
    coverage: 0 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men ACYW',
    coverage: 0 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'POL',
    coverage: 90.86 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'DIPH',
    coverage: 90.77 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'TET',
    coverage: 91.32 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'PER',
    coverage: 90.77 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'EP B',
    coverage: 90.67 }, ...]

我想创建另一个类似于 allDataJson 的 dataJson 对象，但它会对一些值​​求平均值。

例如，在 2016 年我想创建一个新的 DTP 疫苗值，它计算 DIPH、TET 和PER.

同样在 2016 年，我想研制一种 MMRV 疫苗，其值(value)是 MEASLES、MUMPS、RUB 和 VAR 值。

所以 dataJson 看起来像(它包含新值，那些未修改的值，不包含我取平均的值):

[ { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'POL',
    coverage: 95.13 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'DTP',
    coverage: 95.23 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'EP B',
    coverage: 94.72 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'HIB',
    coverage: 94.33 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'MMRV',
    coverage:  68.76 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men C',
    coverage: 89.33 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'PNC',
    coverage: 91.84 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'EP A',
    coverage: 0.87 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'ROTA',
    coverage: 6.39 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men B',
    coverage: 0 },
  { year: 2016,
    country: 'Italy',
    region: 'Piemonte',
    vaccine: 'Men ACYW',
    coverage: 0 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'POL',
    coverage: 90.86 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'DTP',
    coverage:  90.95 },
  { year: 2016,
    country: 'Italy',
    region: 'Valle d\'Aosta',
    vaccine: 'EP B',
    coverage: 90.67 }, ...]

这是我的代码:

global.allDataJson = []; // all data
global.dataJson = []; // data I'm interested in

methods.elaborate = function() {
    for(var i = 0; i < allDataJson.length; i++) {
        var val = allDataJson[i];
        switch(val.year) {
            case 2016:
                if(val.region == 'Piemonte') {
                    var diph = 0;
                    var tet = 0;
                    var per = 0;
                    var mea = 0;
                    var mum = 0;
                    var rub = 0;
                    var vari = 0;
                    if(val.vaccine == 'DIPH') {
                        diph = val.coverage;
                    }
                    else if(val.vaccine == 'TET') {
                        tet = val.coverage;
                    }
                    else if(val.vaccine == 'PER') {
                        per = val.coverage;
                    }
                    else if(val.vaccine == 'MEASLES') {
                        mea = val.coverage;
                    }
                    else if(val.vaccine == 'MUMPS') {
                        mum = val.coverage;
                    }
                    else if(val.vaccine == 'RUB') {
                        rub = val.coverage;
                    }
                    else if(val.vaccine == 'VAR') {
                        vari = val.coverage;
                    }
                    else {
                        var newObj = createJsonObject(2016, val.country, val.vaccine, 'Piemonte', val.coverage);
                        dataJson.push(newObj);
                    }
                    // create DTP value
                    var avgDtp = (diph + tet + per)/3;
                    var newObj = createJsonObject(2016, val.country, 'DTP', 'Piemonte', avgDtp);
                    dataJson.push(newObj);
                    // create MMRV value
                    var avgMmrv = (mea + mum + rub + vari)/4;
                    var newObj = createJsonObject(2016, val.country, 'MMRV', 'Piemonte', avgMmrv);
                    dataJson.push(newObj);
                }
                if(val.region == 'Lombardia') {
                    // same thing for another region
                }
                // same thing for each region

                break;

            case 2000:
                // similar thing for each year
                break;

            default:
                console.log('Switch err in elaborate() function');
        }
    }
}

有没有更聪明的方法来做到这一点？

Answer 1

您应该创建一个变量来维护您的过滤配置:

global.config = [
  {
    year: 2016,
    vaccine: 'DTP',
    country: 'Italy',
    region: 'Piemonte',
    combinedData: [ 'DIPH', 'TET', 'PER' ]
  },
  {
    year: 2016,
    vaccine: 'MMRV',
    country: 'Italy',
    region: 'Piemonte',
    combinedData: [ 'MEASLES', 'MUMPS', 'RUB', 'VAR' ]
  },
  // and so on
]

并将其作为参数传递给函数elaborate:

methods.elaborate = function() {
  for (var i=0; i<config.length; i++ ) {
    var filterDataJson = allDataJson.filter(function(data) {
      return data.country === data.country && data.region === config[i].region && data.year === config[i].year && config[i].combinedData.includes(data.vaccine);
    })

    if (filterDataJson.length > 0) {
      var average = 0;
      for (var j=0; j<filterDataJson.length; j++) {
        average += filterDataJson[j].coverage / filterDataJson.length;
      }
      var newObj = createJsonObject(config[i].year, config[i].vaccine, config[i].country, config[i].region, average);
      dataJson.push(newObj);
    } else {
      console.log("Some meaningful error message here");
    }
  }
}

除非你有充分的理由，否则永远不要在这么多子条件下使用 switch 和 if-else。

编辑:如果所有地区的疫苗都相同，那么您可以像这样对它们进行分组

global.config = [
  {
    year: 2016,
    vaccine: 'DTP',
    country: 'Italy',
    regions: ['Piemonte', 'Lombardia', 'Sicilia', 'Sardegna', ...],
    combinedData: [ 'DIPH', 'TET', 'PER' ]
  },
  {
    year: 2016,
    vaccine: 'MMRV',
    country: 'Italy',
    regions: ['Piemonte', 'Lombardia', 'Sicilia', 'Sardegna', ...],
    combinedData: [ 'MEASLES', 'MUMPS', 'RUB', 'VAR' ]
  },
  // and so on
]

和 elaborate 函数需要稍微扭曲一下:

methods.elaborate = function() {
  for (var i=0; i<config.length; i++ ) {
    for (var k=0; k<config[i].regions.length; k++) {
      var filterDataJson = allDataJson.filter(function(data) {
        return data.country === data.country && data.region === config[i].regions[k] && data.year === config[i].year && config[i].combinedData.includes(data.vaccine);
      })

      if (filterDataJson.length > 0) {
        var average = 0;
        for (var j=0; j<filterDataJson.length; j++) {
          average += filterDataJson[j].coverage / filterDataJson.length;
        }
        var newObj = createJsonObject(config[i].year, config[i].vaccine, config[i].country, config[i].regions[k], average);
        dataJson.push(newObj);
      } else {
        console.log("Some meaningful error message here");
      }
    }
  }
}