如何将数组转换为枢轴数组js答案

【问题标题】：how to convert array to a pivot array js如何将数组转换为枢轴数组js
【发布时间】：2016-07-30 15:00:04
【问题描述】：

您好，我正在尝试根据这些数据创建一个数据透视数组：

    var data = [
  {model_num : "ABC", revision : "AA", value : 31.25, treatment : 'Pressure' },
  {model_num : "ABC", revision : "AA", value : 31.25, treatment : 'Gas' },
  {model_num : "ABC", revision : "AA", value : 33.12, treatment : 'Temp' },
  {model_num : "ABC", revision : "AA", value : 25.87, treatment : 'Current' },
  {model_num : "ABC", revision : "AB", value : 26.63, treatment : 'Pressure' },
  {model_num : "ABC", revision : "AB", value : 26.00, treatment : 'Gas' },
  {model_num : "ABC", revision : "AB", value : 23.75, treatment : 'Temp' }
];

我希望最终结果如下所示：

var data=[{model_num : "ABC", revision : "AA",  "Pressure":31.25, "Gas":31.25, "Temp": 33.12,"Current":25.87 },{model_num : "ABC", revision : "AB", "Gas":26.00,"Temp":23.75}]

我有以下代码：

var arr2d2 = []; //new array that is going to contain the merged values.
    //  console.log(arr2d2.length);
    var arr2d2test = [];
    var counter=0;
    data.map(function(element){
        //console.log(counter); // this will run 7 times the size of data 
        var outerElement = element; //element is equivalent to  one array for example: {model_num : "ABC", revision : "AA", value : 31.25, treatment : 'Pressure' } all 7 in this example
        //console.log(element);
    var found = false; //set initially to false. If not found add element to the new array.
    //console.log(arr2d2.length);
    for (var i = 0; i < arr2d2.length; i++)
    {   
        //console.log(i);
        //console.log(arr2d2[i].model_num);
        if (arr2d2[i].model_num == outerElement.model_num && arr2d2[i].revision == outerElement.revision)
        {
            arr2d2[i][outerElement['treatment']] = outerElement['value'];   
            found = arr2d2[i]; // save the element.
        //   console.log('found variable' + JSON.stringify(found));

           break; //stop the loop
        }
    };

   if (found)
    {
        //arr2d2test.push(found.model_num);//          console.log(found.model_num);
       if (found.value != outerElement.value)
       {
         // console.log('TRUE');
          found.value.push(outerElement.value); //push the age to the new value.
       }
    }
    else
    {
      outerElement.value = [outerElement.value]; //convert age to an array, like you specified.
    //  console.log(outerElement);
      arr2d2.push(outerElement); //not found yet. push element;
    }  
 counter++;
});
//console.log(arr2d2test);
console.log(arr2d2);
console.log(JSON.stringify(arr2d2));

当我控制台记录我的 arr2d2 时，我得到以下信息：

[{"model_num":"ABC","revision":"AA","value":[31.25,33.12,25.87],"treatment":"Pressure","Gas":31.25,"Temp":33.12,"Current":25.87},{"model_num":"ABC","revision":"AB","value":[26.63,26,23.75],"treatment":"Pressure","Gas":26,"Temp":23.75}]

这很接近但不完全是我需要的。任何帮助将不胜感激。

【问题讨论】：

标签： javascript arrays json sorting pivot

【解决方案1】：

您可以使用forEach 循环和可选的thisArg 参数来获得所需的结果。

var data = [
  {model_num : "ABC", revision : "AA", value : 31.25, treatment : 'Pressure' },
  {model_num : "ABC", revision : "AA", value : 31.25, treatment : 'Gas' },
  {model_num : "ABC", revision : "AA", value : 33.12, treatment : 'Temp' },
  {model_num : "ABC", revision : "AA", value : 25.87, treatment : 'Current' },
  {model_num : "ABC", revision : "AB", value : 26.63, treatment : 'Pressure' },
  {model_num : "ABC", revision : "AB", value : 26.00, treatment : 'Gas' },
  {model_num : "ABC", revision : "AB", value : 23.75, treatment : 'Temp' }
];


var result = [];
data.forEach(function(e) {
  var a = e.model_num + '|' + e.revision;
   if(!this[a]) {
    this[a] = {model_num: e.model_num, revision: e.revision}
    result.push(this[a]);
  }
  this[a][e.treatment] = e.value;
}, {});

document.body.innerHTML = '<pre>' + JSON.stringify(result, 0, 4) + '</pre>';

【讨论】：