intersecting multidimensional array in javascript

Question

let say i have 1 multidimensional array and i want to exclude values that not equal in javascript.

here is the example array.

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]
    }
};

i want to convert that array to be like this.

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

here is my code

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);

actually i could do this code

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);

but i need to convert it through filter variable. i could not use filter[0] and filter[1], because that values could change dynamically and could be more than 2 values in array.

I guess that's because you haven't shown any attempt yourself. And I personally don't see the pattern here. — Jonas Wilms
– Jonas Wilms, Commented Feb 20, 2019 at 11:12
@JonasWilms i have mentioned that i could done it if there were 2 arrays separated.. so should i need to put code with 2 arrays separated? — Willyanto Halim
– Willyanto Halim, Commented Feb 20, 2019 at 11:14
@FZs could you read the question first before you said it duplicate question? — Willyanto Halim
– Willyanto Halim, Commented Feb 20, 2019 at 11:45

adiga · Accepted Answer · 2019-02-22 20:38:05Z

2

You could loop through the keys and update the values using filter and includes:

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)

If you don't want to mutate the original object then use Object.entries and 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)

If you have more than 2 array properties, you can do something like this: Get all the arrays using Object.values and then use reduce to run the previous code recursively

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)

edited Feb 22, 2019 at 20:38

answered Feb 20, 2019 at 10:48

adiga

35.4k9 gold badges65 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

12 Comments

Willyanto Halim Over a year ago

sorry, i forget to put filter variable.. it should loop through that variable.. i have update the question..

adiga Over a year ago

What do you mean by filter variable? Instead of arrays[key]["big_number"], do arrays[key][filter[0]] and filter[1] for odds_number

Willyanto Halim Over a year ago

yes.. filter variable value is ["big_number", "odds_number"] and the variable could change dynamically through checkbox.. so i want to loop it through that filter variable..

adiga Over a year ago

Do as mentioned in the previous comment.

adiga Over a year ago

@WillyantoHalim Intersection is getting items common to all arrays. If one of them is empty, then result will be empty array. This is valid

|

FZs · Accepted Answer · 2019-02-20 14:14:34Z

1

Here is a little intersection snippet:

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

Using that, you can do this easily:

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)

edited Feb 20, 2019 at 14:14

answered Feb 20, 2019 at 10:53

FZs

18.8k13 gold badges47 silver badges56 bronze badges

2 Comments

Willyanto Halim Over a year ago

you can have a look for the updated question and remove that duplicate question tag.. thanks

FZs Over a year ago

@WillyantoHalim I updated my answer to be dynamic. And sorry for the duplicate mark, I can't remove that, but only you can see; simply ignore it. Happy coding!

random · Accepted Answer · 2019-02-20 10:50:31Z

0

use Object.entries to get keys and values and then use 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);

answered Feb 20, 2019 at 10:50

random

7,9093 gold badges21 silver badges25 bronze badges

1 Comment

Willyanto Halim Over a year ago

sorry, i forget to put filter variable.. it should loop through that variable.. i have update the question.

Hassan Imam · Accepted Answer · 2019-02-20 10:53:39Z

0

You can get the unique values from both the arrays using Set and then using filter get only the common values.

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)

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Feb 20, 2019 at 10:53

answered Feb 20, 2019 at 10:52

Hassan Imam

22.6k6 gold badges45 silver badges53 bronze badges

1 Comment

Willyanto Halim Over a year ago

sorry, i forget to put filter variable.. it should loop through that variable.. i have update the question.

Collectives™ on Stack Overflow

intersecting multidimensional array in javascript

4 Answers 4

12 Comments

2 Comments

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

12 Comments

2 Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related