对数组值进行分组并添加属性

如何解决对数组值进行分组并添加属性

有人知道一种通过对象键对对象数组进行分组的方法吗？例如，我有很多汽车物品：

const cars = [
  "fiat-palio","fiat-stilo","fiat-strada","fiat-uno","gm-corsa","gm-celta","ford-fiesta","volkswagen-gol","volkswagen-voyage"
]

我想按每个汽车制造商分组创建新的汽车对象阵列：

{ 
  "fiat": { 
    "palio": 1,"stilo": 1,"strada": 1,"uno": 2 
  },"gm": { 
    "corsa": 1,"celta": 1 
  },"ford": { 
    "fiesta": 1 
  },"volkswagen": { 
    "gol": 3,"voyage": 1 
  }
}

解决方法

您可以使用array的reduce方法产生所需的输出。

reduce在每次迭代中获取数组先前项和当前项，并返回标量值。 here the documentation

const cars = [
  "fiat-palio","fiat-stilo","fiat-strada","fiat-uno","gm-corsa","gm-celta","ford-fiesta","volkswagen-gol","volkswagen-voyage"
];

let result = cars.reduce((obj,item) => {
  let pair = item.split('-'); // split key and value
  let mark = pair[0]; 
  let model = pair[1];

  if(!obj.hasOwnProperty(mark)) { // initialize new mark and model
     obj[mark] = {};
     obj[mark][model] = 1;
  } else {
    if(obj[mark].hasOwnProperty(model)) { // increment existing model 
      obj[mark][model] += 1; 
    } else { // initialize model of existing mark
       obj[mark][model] = 1;
    }
  }

  return obj;
},{}) 


console.log(result)

,

您可以拆分每辆车并破坏阵列，以获取品牌和型号。识别这些值之后，只需将这些值分布在一个减速器上即可。

const cars = [
  "fiat-palio","volkswagen-voyage"
];

const frequency = cars.reduce((groups,car) => ({
  ...groups,...(([make,model]) => ({
    [make] : {
      ...groups?.[make],[model] : (groups?.[make]?.[model] || 0) + 1
    }
  }))(car.split('-'))
}),{});

console.log(frequency);

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编码高尔夫乐趣

f=l=>l.reduce((g,c)=>({...g,...(([m,n])=>({[m]:{...g?.[m],[n]:(g?.[m]?.[n]||0)+1}}))(c.split('-'))}),{})（104个字节）

用法：只需将cars传递到上面的f函数中即可。