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javascript - 计算 json 数组对象并使用 SUM 结果创建一个新数组

问题描述

我有一个像这样的 JSON 数组，

const arrayVal = [{
    "DATE": "2020-12-1",
    "NAME": "JAKE",
    "TEAM_NO": 2,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "ANNA",
    "TEAM_NO": 2,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "JEFF",
    "TEAM_NO": 1,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "ERIKA",
    "TEAM_NO": 2,
   
}, {
    "DATE": "2020-12-1",
    "NAME": "SUTTON",
    "TEAM_NO": 3,
}, {
    "DATE": "2020-12-1",
    "NAME": "ARNOLD",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "JAKE",
    "TEAM_NO": 4,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ANNA",
    "TEAM_NO": 2,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "JEFF",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ERIKA",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "SUTTON",
    "TEAM_NO": 5,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ARNOLD",
    "TEAM_NO": 5,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "JAKE",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ANNA",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "JEFF",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ERIKA",
    "TEAM_NO": 2,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "SUTTON",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ARNOLD",
    "TEAM_NO": 3,
      
}];

我只是想从上面的数组中得到下面的结果。在此我想按天计算团队人数并使用“TEAM_NO_COUNT”参数创建一个新数组。

[{
    "DATE": "2020-12-1",
    "TEAM_NO": 3, 
    "TEAM_NO_COUNT": 2, // 2 entries with no 3 team
     
}, {
    "DATE": "2020-12-1",
    "TEAM_NO": 1,
    "TEAM_NO_COUNT": 2,  // 2 entries with no 1 team
}, {
    "DATE": "2020-12-2",
    "TEAM_NO": 4,
    "TEAM_NO_COUNT": 1,  
}]

到目前为止我有这段代码，但它只是给了我一个带有计数团队编号的 json 对象，但这不是我想要的，我需要上面的确切结果。

TEAM_NO_COUNT = {}; // create an object
$.each(JSON.parse(JSON.stringify(arrayVal)), function (key, val) {

DATE_NO_CO = {};

  TEAM_NO_COUNT[val.DATE] = (TEAM_NO_COUNT[val.DATE] || {});

  TEAM_NO_COUNT[val.DATE][val.TEAM_NO] = (TEAM_NO_COUNT[val.DATE][val.TEAM_NO] || 0) + 1;
  
});

alert(JSON.stringify(TEAM_NO_COUNT));

有人可以帮我吗。将不胜感激。谢谢。

标签： javascriptjqueryarraysjsonreduce

解决方案

功能解决方案：

reduce() 方法对数组的每个元素执行一个 reducer 函数（您提供），从而产生单个输出值。

reducer 函数有四个参数：累加器、当前值、当前索引和源数组

更多信息请参阅：MDN 网络文档 - Reduce()

const arrayVal = [{
    "DATE": "2020-12-1",
    "NAME": "JAKE",
    "TEAM_NO": 2,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "ANNA",
    "TEAM_NO": 2,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "JEFF",
    "TEAM_NO": 1,
    
}, {
    "DATE": "2020-12-1",
    "NAME": "ERIKA",
    "TEAM_NO": 2,
   
}, {
    "DATE": "2020-12-1",
    "NAME": "SUTTON",
    "TEAM_NO": 3,
}, {
    "DATE": "2020-12-1",
    "NAME": "ARNOLD",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "JAKE",
    "TEAM_NO": 4,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ANNA",
    "TEAM_NO": 2,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "JEFF",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ERIKA",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "SUTTON",
    "TEAM_NO": 5,
     
}, {
    "DATE": "2020-12-2",
    "NAME": "ARNOLD",
    "TEAM_NO": 5,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "JAKE",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ANNA",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "JEFF",
    "TEAM_NO": 1,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ERIKA",
    "TEAM_NO": 2,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "SUTTON",
    "TEAM_NO": 3,
     
}, {
    "DATE": "2020-12-3",
    "NAME": "ARNOLD",
    "TEAM_NO": 3,
      
}];

const result = arrayVal.reduce((curr, entry) => {
    const {DATE, NAME, TEAM_NO} = entry;
  
  const newEntry = {DATE, TEAM_NO, "TEAM_NO_COUNT": 1};
    const currEntry = curr.find(currEntry => currEntry.DATE === DATE && currEntry.TEAM_NO === TEAM_NO);
  
  if(currEntry == null) {
    return [...curr, {...newEntry}];
  } else {
    return [
        ...curr.filter(currEntry => !(currEntry.DATE === DATE && currEntry.TEAM_NO === TEAM_NO)),
      {...newEntry, "TEAM_NO_COUNT": currEntry.TEAM_NO_COUNT + 1}
    ];
  }
}, []);

console.log(result);

通过这个方向，您可以重建整个对象数组。如果您需要扩展此数据，它会很有用。例如，如果您想包含球员姓名列表。

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