唯一属性计数 json答案

【问题标题】：unique attribute count json唯一属性计数 json
【发布时间】：2016-06-15 06:42:20
【问题描述】：

我有一个json文件如下

 {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]}

提取 f3 的唯一属性值的最佳方法是什么。

在我们的示例中，我应该将唯一的 f3 属性存储在一个数组中，该数组应该有 ["Jun-2016","May-2016","Aug-2016"]

【问题讨论】：

标签： javascript jquery json performance

【解决方案1】：

使用Array#reduce方法

var data= {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]};

var res = data.Teams.reduce(function(arr, ele) {
  // check element already exist if not push the value to the array
  if (arr.indexOf(ele.f3) === -1) arr.push(ele.f3);
  return arr;
  // set initial value as empty array
}, []);

console.log(res);

【讨论】：

您能否更改代码以将数据推送到 json 数组而不是数组结果应采用以下格式 {"f3":"Aug-2016","f3":"May-2016 ","f3":"Jun-2016"} ?
@user3349850：Json 数组？ JSON.stringify(rs)
@user3349850 : {"f3":"Aug-2016","f3":"May-2016","f3":"Jun-2016"} == {"f3":"Jun-2016"} ，但这是可能的[{"f3":"Aug-2016"},{"f3":"May-2016"},{"f3":"Jun-2016"}]

【解决方案2】：

var arrnew = []


var data = {
  "Teams": [{
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "May-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Aug-2016",
    "color": "R"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Jun-2016",
    "color": "R"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "May-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "May-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Jun-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Jun-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Aug-2016",
    "color": "R"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "May-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "Jun-2016",
    "color": "G"
  }, {
    "id": "1",
    "f1": "Currency",
    "f2": "All",
    "f3": "May-2016",
    "color": "G"
  }, ]
}



$.each(data.Teams, function(i, v) {
  
  if ($.inArray(v.f3, arrnew) == -1) {
    arrnew.push(v.f3);
  };

})

console.log(arrnew)

&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"&gt;&lt;/script&gt;

迭代数据
创建新数组，如果不推送值，则检查数组中是否存在值

【讨论】：

【解决方案3】：

您可以使用forEach & indexOf 方法来查找唯一的 f3 值

var x= {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]}
var _m =(x.Teams);
var uniquef3 = [];
_m.forEach(function(item){
 if(uniquef3.indexOf(item.f3) ==-1){
    uniquef3.push(item.f3)
 }

})
console.log(uniquef3)

JSFIDDLE

【讨论】：

【解决方案4】：

试试这个

var x ={"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]}

newaArr =[]

angular.forEach(x.Teams,function(val,index){
if(newaArr.indexOf(val.f3) ==-1){
newaArr.push(val.f3)
}

})

【讨论】：

【解决方案5】：

这是可以做到的一些优化的方式。您可以缓存 f3 的唯一值。下次只需使用 javascript 的 hasOwnProperty 检查它们的存在。这将降低搜索存在的复杂性。

 var Teams = [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
];

var output=[];
var cache = {};

for(var i in Teams) {
  if(!cache.hasOwnProperty(Teams[i].f3)) {
    cache[Teams[i].f3] = null;
  }
}
for(var key in cache) {
  output.push(key);
}
console.log(output);

【讨论】：

【解决方案6】：

你可以这样做：

var unique={}
var kt= {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]};

kt.Teams.forEach(function(value){unique[value.f3]=0;});
console.log(Object.keys(unique));

希望对你有帮助

【讨论】：