从对象数组中计算特定键值 [英] Count particular key value from array of object

问题描述

我有以下 JSON 数组我想创建对象表单状态键计数

<预><代码>[{"id": "65:0",状态":橙色"},{"id": "65:0",状态":绿色"},{"id": "65:0",状态":橙色"},{"id": "65:0",状态":黄色"},{"id": "65:0",状态":红色"},{"id": "65:0",状态":绿色"},{"id": "65:0",状态":绿色"},{"id": "65:0",状态":橙色"},{"id": "65:0",状态":黄色"},{"id": "65:0",状态":绿色"}]

想要统计状态键值并创建以下对象

<代码>{'橙色' : 3,'绿色' : 4,'黄色' : 2,'红色' : 1,}

解决方案

使用 Array#reduce 方法

var res = data.reduce(function(obj, v) {//增加或设置属性//`(obj[v.status] || 0)` 如果定义了则返回属性值//或 0(因为 `undefined` 是一个假值obj[v.status] = (obj[v.status] || 0) + 1;//返回更新后的对象返回对象；//将初始值设置为对象}, {})

var data = [{"id": "65:0",状态":橙色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":橙色"}, {"id": "65:0",状态":黄色"}, {"id": "65:0",状态":红色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":橙色"}, {"id": "65:0",状态":黄色"}, {"id": "65:0",状态":绿色"}];var res = data.reduce(function(obj, v) {obj[v.status] = (obj[v.status] || 0) + 1;返回对象；}, {})console.log(res);

<小时>

虽然你可以使用 Array#forEach 方法相同的代码.

var res = {};data.forEach(function(v) {res[v.status] = (res[v.status] || 0) + 1;})

var data = [{"id": "65:0",状态":橙色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":橙色"}, {"id": "65:0",状态":黄色"}, {"id": "65:0",状态":红色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":绿色"}, {"id": "65:0",状态":橙色"}, {"id": "65:0",状态":黄色"}, {"id": "65:0",状态":绿色"}];var res = {};data.forEach(function(v) {res[v.status] = (res[v.status] || 0) + 1;})console.log(res);

I have following JSON array I want to create object form status key count

[
  {
    "id": "65:0",    
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "RED"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
   {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  }
] 

Want to count status key value and create the following Object

{
 'ORANGE' : 3,
 'GREEN' : 4,
 'YELLOW' : 2,
 'RED' : 1,
}

解决方案

Use Array#reduce method

var res = data.reduce(function(obj, v) {
  // increment or set the property
  // `(obj[v.status] || 0)` returns the property value if defined
  // or 0 ( since `undefined` is a falsy value
  obj[v.status] = (obj[v.status] || 0) + 1;
  // return the updated object
  return obj;
  // set the initial value as an object
}, {})

var data = [{
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "RED"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "GREEN"
}];

var res = data.reduce(function(obj, v) {
  obj[v.status] = (obj[v.status] || 0) + 1;
  return obj;
}, {})

console.log(res);

---

Although you can use Array#forEach method with the same code.

var res = {};
data.forEach(function(v) {
  res[v.status] = (res[v.status] || 0) + 1;
})

var data = [{
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "RED"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "GREEN"
}];

var res = {};
data.forEach(function(v) {
  res[v.status] = (res[v.status] || 0) + 1;
})

console.log(res);

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