检查动态填充的数组中的重复对象答案

【问题标题】：Check for duplicated objects in an array populated dynamically检查动态填充的数组中的重复对象
【发布时间】：2019-03-29 16:43:47
【问题描述】：

我正在尝试构建一个数据结构，其中所有元素都将根据对象键进行分组。

一切正常，除了我无法检查新数组是否有重复的数据，因为它在for..of 循环之外。我正在寻找一种方法来防止push在新数组已经拥有另一个对象的情况下使用它。

当前输出（注意来自日本的字符列表出现了两次）

[
  [
    { "country": "US" },
    [
      { "name": "Guile", "country": "US" }
    ]
  ],
  [
    { "country": "Japan" },
    [
      { "name": "E. Honda", "country": "Japan" },
      { "name": "Ryu", "country": "Japan" }
    ]
  ],
  [
    { "country": "Japan" },
    [
      { "name": "E. Honda", "country": "Japan" },
      { "name": "Ryu", "country": "Japan" }
    ]
  ],
  [
    { "country": "Thailand" },
    [
      { "name": "Sagat", "country": "Thailand" }
    ]
  ]
]

预期输出

[
  [
    { "country": "US" },
    [
      { "name": "Guile", "country": "US" }
    ]
  ],
  [
    { "country": "Japan" },
    [
      { "name": "E. Honda", "country": "Japan" },
      { "name": "Ryu", "country": "Japan" }
    ]
  ],
  [
    { "country": "Thailand" },
    [
      { "name": "Sagat", "country": "Thailand" }
    ]
  ]
]

我目前所拥有的

var data = [
  {name: 'Guile', country: 'US'},
  {name: 'E. Honda', country: 'Japan'},
  {name: 'Ryu', country: 'Japan'},
  {name: 'Sagat', country: 'Thailand'}
]

const getNationList = (streetFighterList) => {
  let filteredList = []
  for (const [index, characterData] of streetFighterList.entries()) {
    // .......................................................
    // looking for ways here to check if `filteredList` already
    // has the data I'm trying to push. Since it's empty
    // I don't know how to check its index. :(
    // NOTE: indexOf() doesn't seem to work
    // .......................................................
    const indexOf = filteredList.indexOf(streetFighterList[index].country)
    if (indexOf == -1) {
      filteredList.push([
        { country: characterData.country },
        streetFighterList.filter((character) => {
          return character.country === characterData.country
        })
      ])
    }
  }
  return filteredList
}

console.log(getNationList(data))

注意：我知道，鉴于 country 对象始终是唯一的，如果我改用字符串，这个数据结构会更好、更容易。然而，这是一个示例数据，在现实生活中的代码中，我确实需要将它存储为一个对象。

【问题讨论】：

是否可以将您的对象格式更改为 { [country]: [names] }？那么更容易删除重复并找到属于同一国家/地区的名称
很遗憾没有。我需要 obj 键是不可变的

标签： javascript arrays loops for-loop

【解决方案1】：

我会推荐使用一些来验证如下

var data = [
  {name: 'Guile', country: 'US'},
  {name: 'E. Honda', country: 'Japan'},
  {name: 'Ryu', country: 'Japan'},
  {name: 'Sagat', country: 'Thailand'}
]

const getNationList = (streetFighterList) => {
  let filteredList = []
  for (const [index, characterData] of streetFighterList.entries()) {

    const entry = filteredList.some(item => item[0].country === streetFighterList[index].country)
    if (!entry) {
      filteredList.push([
        { country: characterData.country },
        streetFighterList.filter((character) => {
          return character.country === characterData.country
        })
      ])
    }
  }
  return filteredList
}

console.log(getNationList(data))

【讨论】：

【解决方案2】：

将数组简化为对象，以国家名称为键。将同一国家下的玩家组合成一个对象，以玩家的名字为key。

完成后，使用Object.values() 转换回数组，并映射数组以将玩家的对象也通过Object.values() 转换为数组。

const data = [[{"country":"US"},[{"name":"Guile","country":"US"}]],[{"country":"Japan"},[{"name":"E. Honda","country":"Japan"},{"name":"Ryu","country":"Japan"}]],[{"country":"Japan"},[{"name":"E. Honda","country":"Japan"},{"name":"Ryu","country":"Japan"}]],[{"country":"Thailand"},[{"name":"Sagat","country":"Thailand"}]]]

const result = Object.values(data.reduce((r, [c, p]) => { 
  if(!r[c.country]) r[c.country] = [c, {}]
  
  const players = r[c.country][1];
  
  p.forEach(o => { if(!players[o.name]) players[o.name] = o; })
  
  return r;
}, {})).map(([c, p]) => [c, Object.values(p)]);

console.log(result)

【讨论】：

【解决方案3】：

您可以先创建一个包含不同国家/地区的Set，然后遍历它们，将每个国家与来自该国家/地区的战士列表结合起来。例如：

const data = [{ name: 'Guile', country: 'US' }, { name: 'E. Honda', country: 'Japan' }, { name: 'Ryu', country: 'Japan' }, { name: 'Sagat', country: 'Thailand' }];
const countries = new Set(data.map((obj) => obj.country));
const output = [...countries].map((country) => {
  const entries = data.filter((obj) => obj.country === country);
  return [{ country }, entries];
});

console.log(output);
/*
[
  [
    {"country": "US"},
    [{"name": "Guile", "country": "US"}]
  ],
  [
    {"country": "Japan"},
    [{"name": "E. Honda", "country": "Japan"}, {"name": "Ryu", "country": "Japan" }]
  ],
  [
    {"country": "Thailand"},
    [{"name": "Sagat", "country": "Thailand"}]
  ]
]
*/

【讨论】：