6

请看这个例子：JsFiddle

问：我有以下JSON Array

y= [ {"LngTrend":15,"DblValue":10,"DtmStamp":1358226000000},     
{"LngTrend":16,"DblValue":92,"DtmStamp":1358226000000},    
{"LngTrend":17,"DblValue":45,"DtmStamp":1358226000000},
{"LngTrend":18,"DblValue":87,"DtmStamp":1358226000000},


{"LngTrend":15,"DblValue":10,"DtmStamp":1358226060000},
{"LngTrend":16,"DblValue":87,"DtmStamp":1358226060000},
{"LngTrend":17,"DblValue":45,"DtmStamp":1358226060000},
{"LngTrend":18,"DblValue":92,"DtmStamp":1358226060000} ]

我试图通过DtmStamp最终得到这样的东西来对这些对象进行分组：

 x =  [[1358226000000,10,92,45,87],[1358226060000,10,87,45,92], .......]

换句话说：

x[0][0] = y[0].DtmStamp ;
x[0][1] = y[0].LngTrend ;
x[0][2] = y[1].LngTrend ;
x[0][3] = y[2].LngTrend ; 
x[0][4] = y[3].LngTrend ;

不幸的是，它以我不想要的东西结束。

这是我到目前为止所尝试的：

   var dataTrendArray = [];
           $.each(x, function (index, value) {
                var trendArray = [];
                if (index % 4 == 0) {
                    trendArray.push(x[index].DtmStamp);
                    for (var i = 0; i < 4; i++) {
                        index = eval(index + i);
                        trendArray.push(x[index].DblValue);
                    }
                }

               console.log(trendArray) ;
                dataTrendArray.push(trendArray);
            });

有人可以帮助我走上正确的道路吗？

4

5 回答 5

17

您可以将 JavaScript 对象用作类似于地图的键/值数据结构。属性名称将作为键，而属性值将作为值。这将允许您进行分组。

var y = [
     {"LngTrend":15,"DblValue":10,"DtmStamp":1358226000000},     
     {"LngTrend":16,"DblValue":92,"DtmStamp":1358226000000},    
     {"LngTrend":17,"DblValue":45,"DtmStamp":1358226000000},
     {"LngTrend":18,"DblValue":87,"DtmStamp":1358226000000},
     {"LngTrend":15,"DblValue":10,"DtmStamp":1358226060000},
     {"LngTrend":16,"DblValue":87,"DtmStamp":1358226060000},
     {"LngTrend":17,"DblValue":45,"DtmStamp":1358226060000},
     {"LngTrend":18,"DblValue":92,"DtmStamp":1358226060000},
];

var x = {};

for (var i = 0; i < y.length; ++i) {
    var obj = y[i];

    //If a property for this DtmStamp does not exist yet, create
    if (x[obj.DtmStamp] === undefined)
        x[obj.DtmStamp] = [obj.DtmStamp]; //Assign a new array with the first element of DtmStamp.

    //x will always be the array corresponding to the current DtmStamp. Push a value the current value to it.
    x[obj.DtmStamp].push(obj.DblValue);
}

console.log(x); //x is now an object grouped by DtmStamp. You can easily turn it back into an array here.
于 2013-01-29T21:54:12.440 回答
8

您应该使用哈希。哈希将允许您轻松索引所有DblValue值DtmStamp。这是一个完整的工作示例：

jsFiddle

var y = [ {"LngTrend":15,"DblValue":10,"DtmStamp":1358226000000},     
{"LngTrend":16,"DblValue":92,"DtmStamp":1358226000000},    
{"LngTrend":17,"DblValue":45,"DtmStamp":1358226000000},
{"LngTrend":18,"DblValue":87,"DtmStamp":1358226000000},
{"LngTrend":15,"DblValue":10,"DtmStamp":1358226060000},
{"LngTrend":16,"DblValue":87,"DtmStamp":1358226060000},
{"LngTrend":17,"DblValue":45,"DtmStamp":1358226060000},
{"LngTrend":18,"DblValue":92,"DtmStamp":1358226060000} ];

var x = {};

var i = 0;
while(i++ < y.length) {
    var key = y[i].DtmStamp.toString();
    if (typeof(x[key]) == "undefined") x[key] = [];
    x[key].push(y[i].DblValue);
}

alert(JSON.stringify(x));

关键是对要分组的值使用散列。

结果：

{
    "1358226060000": [
        92,
        45,
        87,
        10
    ],
    "1358226000000": [
        87,
        45,
        92,
        10
    ]
}

if/then如果你想防止重复，你可以通过添加逻辑来做到这一点indexOf()。

于 2013-01-29T21:53:02.227 回答
0

trendArray即使未填充 ( index % 4 != 0)，您的代码也会推送空s。相反，使用这个：

var dataTrendArray = [];
for (var i = 0; i < x.length; i += 4) {
    var trendArray = [ x[i].DtmStamp ];
    for (var j = i, l = Math.max(i + 4, x.length); j < l; j++) {
        trendArray.push(x[j].DblValue);
    }
    // console.log(trendArray) ;
     dataTrendArray.push(trendArray);
}

DtmStamp但是，如果您只是使用as 键将 trendArrays 分组到一个对象中，它可能会更合适：

var dataTrend = {};
for (var i=0; i<x.length; i++) {
    var key = x[i].DtmStamp;
    if (key in dataTrend)
        dataTrend[key].push(x[i].DblValue);
    else
        dataTrend[key] = [ x[i].DblValue ];
}
于 2013-01-29T22:28:40.080 回答
0

您可以构建一个由 DtmStamp 索引的稀疏数组。

var x = [];
$.each(y, function(i, obj) {
    var s = obj.DtmStamp;
    if(!x[s]) x[s] = [];
    x[s].push(obj.DblValue);
});

//x is now a sparse array, indexed by DtmStamp

与对象相比，这具有优势，即数组元素按 DtmStamp 顺序排列。

//To loop through x
for(i in x) {
    ...
}
于 2013-01-29T22:35:41.613 回答
0 
 var y = [
   {"LngTrend":15,"DblValue":10,"DtmStamp":1358226000000},     
   {"LngTrend":16,"DblValue":92,"DtmStamp":1358226000000},    
   {"LngTrend":17,"DblValue":45,"DtmStamp":1358226000000},
   {"LngTrend":18,"DblValue":87,"DtmStamp":1358226000000},
   {"LngTrend":15,"DblValue":10,"DtmStamp":1358226060000},
   {"LngTrend":16,"DblValue":87,"DtmStamp":1358226060000},
   {"LngTrend":17,"DblValue":45,"DtmStamp":1358226060000},
   {"LngTrend":18,"DblValue":92,"DtmStamp":1358226060000},
 ];
var x = {};

for(var k in y){
  if(x[y[k]["DtmStamp"]] == undefined)
     x[y[k]["DtmStamp"]] = [];
     x[y[k]["DtmStamp"]].push(y[k]["DblValue"])
}
alert(JSON.stringify(x))
console.log(x);

见http://plnkr.co/edit/511sKSdzHGYuvpYqKCPD?p=preview

于 2014-10-20T05:39:26.100 回答