javascript 中的相交多维数组

Question

假设我有 1 个多维数组，我想排除 javascript 中不相等的值。

这里是示例数组。

var filter = ["big_number", "odds_number"];
var arrays = {
    "first" : {
        "big_number" : [50,51,52],
        "odds_number" : [39,41,51,53]
    },
    "second" : {
        "big_number" : [61,62,63,64,65,70,72,73],
        "odds_number" : [13,15,17,19,61,63,65,73]
    }
};

我想将该数组转换成这样。

var new_arrays = {
    "first" : [51],
    "second" : [61,63,65,73]
};

这是我的代码

var newArray = {
    "first" : [],
    "second" : []
};
for (var k in arrays){
    if (arrays.hasOwnProperty(k)) {
        for(var f=0; f<filter.length; f++) {
            newArray[k].push(arrays[k][filter[f]].filter(value => -1 !== arrays[k][filter[f]].indexOf(value))));
        }
   }
}
console.log(newArray);

其实我可以做这个代码

var newArray = {
    "first" : [],
    "second" : []
};
for (var k in arrays){
    if (arrays.hasOwnProperty(k)) {
        newArray[k].push(arrays[k]["big_number"].filter(value => -1 !== arrays[k]["odds_number"].indexOf(value))));
    }
}
console.log(newArray);

但我需要通过 filter variable 转换它。我无法使用 filter[0] and filter[1]，因为该值可能会动态变化，并且数组中的值可能超过 2 个。

Answer 1

您可以遍历键并使用 filter and includes:

更新值

var arrays={"first":{"big_number":[50,51,52],"odds_number":[39,41,51,53]},"second":{"big_number":[61,62,63,64,65,70,72,73],"odds_number":[13,15,17,19,61,63,65,73]}};

for (let key in arrays) {
  arrays[key] = arrays[key]["big_number"]
                  .filter(n => arrays[key]["odds_number"].includes(n));
}

console.log(arrays)

如果您不想改变原始对象，请使用 Object.entries 和 reduce:

var arrays={"first":{"big_number":[50,51,52],"odds_number":[39,41,51,53]},"second":{"big_number":[61,62,63,64,65,70,72,73],"odds_number":[13,15,17,19,61,63,65,73]}};

const newObject = Object.entries(arrays).reduce((r, [key, {big_number, odds_number}]) => {
  r[key] = big_number.filter(n => odds_number.includes(n));
  return r
}, {})

console.log(newObject)

如果你有2个以上的数组属性，你可以这样做：使用Object.values获取所有数组，然后使用reduce递归到运行前面的代码

var arrays = {
  "first": {
    "big_number": [50, 51, 52],
    "odds_number": [39, 41, 51, 53],
    "another_key": [41, 51, 53]
  },
  "second": {
    "big_number": [61, 62, 63, 64, 65, 70, 72, 73],
    "odds_number": [13, 15, 17, 19, 61, 63, 65, 73],
    "another_key": [63, 65]
  }
};

for (let key in arrays) {
  arrays[key] = Object.values(arrays[key])
                       .reduce((a, b) => a.filter(c => b.includes(c)))
}

console.log(arrays)

Answer 2

使用Object.entries获取键和值然后使用reduce

var arrays = {
  "first" : {
      "big_number" : [50,51,52],
      "odds_number" : [39,41,51,53]
  },
  "second" : {
      "big_number" : [61,62,63,64,65,70,72,73],
      "odds_number" : [13,15,17,19,61,63,65,73]
  }
};

const output =Object.entries(arrays).reduce((accu, [key, {big_number}]) => {
  if(!accu[key]) accu[key] = [];
  big_number.forEach(num => {
    if(num%2 !==0)
    accu[key].push(num);
  })
  return accu;
}, {});

console.log(output);

Answer 3

您可以使用 Set 从两个数组中获取唯一值，然后使用 filter 仅获取公共值。

var arrays = {"first": {"big_number": [50, 51, 52],"odds_number": [39, 41, 51, 53]},"second": {"big_number": [61, 62, 63, 64, 65, 70, 72, 73],"odds_number": [13, 15, 17, 19, 61, 63, 65, 73]}},
    result = Object.keys(arrays).reduce((r,k) => {
      let setB = new Set(arrays[k]["big_number"]);
      r[k] = [...new Set(arrays[k]["odds_number"])].filter(x => setB.has(x));
      return r;
    },{});
console.log(result)

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Answer 4

这里有一个小交叉片段：

function intersect(a,b){
    b.slice()
    return a.filter(item=>{
        if(b.includes(item)){
            b.splice(b.indexOf(item),1)
            return true
        }
    })
}

使用它，您可以轻松做到这一点：

function intersect(a,b){
 b.slice()
 return a.filter(item=>{
  if(b.includes(item)){
   b.splice(b.indexOf(item),1)
   return true
  }
 })
}

var filter = ["big_number", "odds_number"];
var output={}
var arrays = {
    "first" : {
        "big_number" : [50,51,52],
        "odds_number" : [39,41,51,53]
    },
    "second" : {
        "big_number" : [61,62,63,64,65,70,72,73],
        "odds_number" : [13,15,17,19,61,63,65,73]
    }
};
for(x in arrays){
    output[x]=arrays[x][filter[0]]
    for(let i=1;i<filter.length;i++){
        output[x]=intersect(output[x],arrays[x][filter[i]])
    }
}
console.log (output)

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