How to remove duplicates in one of two arrays?

Question

So I have two arrays looking like this :

arr 1 :

[[Tue Feb 20 09:00:00 GMT+01:00 2018, xxx, cc0902be495c4350a6bfcd1734c843b9, xxx, affiliate, 101723.0, ru, 9e09ee193e21766b1946e485eec9adcf, 0.81, 0.72, 6.05, 0.5265, 0.1053, 0.6318, 3.9325, 0.7865, 4.719, 0.468, 0.0936, 0.5616], [Tue Feb 21 09:00:00 GMT+01:00 2018, xxx, f8875453e5354d88931e3474021f723a, xxx, affiliate, 101723.0, ru, b4cb6e13bc1909b6f04f8cd44b1374d5, 0.5, 0.44, 3.72, 0.325, 0.065, 0.39, 2.418, 0.4836, 2.9016, 0.286, 0.0572, 0.3432],[Tue Feb 22 09:00:00 GMT+01:00 2018, xxx, f8875453e5354d88931e3474021f723a, xxx, affiliate, 101723.0, ru, b4cb6e13bc1909b6f04f8cd44b1374d5, 0.5, 0.44, 3.72, 0.325, 0.065, 0.39, 2.418, 0.4836, 2.9016, 0.286, 0.0572, 0.3432]]

arr 2 :

[[Tue Feb 20 09:00:00 GMT+01:00 2018, xxx, cc0902be495c4350a6bfcd1734c843b9, xxx, affiliate, 101723.0, ru, 9e09ee193e21766b1946e485eec9adcf, 0.81, 0.72, 6.05, 0.5265, 0.1053, 0.6318, 3.9325, 0.7865, 4.719, 0.468, 0.0936, 0.5616], [Tue Feb 21 09:00:00 GMT+01:00 2018, xxx, f8875453e5354d88931e3474021f723a, xxx, affiliate, 101723.0, ru, b4cb6e13bc1909b6f04f8cd44b1374d5, 0.5, 0.44, 3.72, 0.325, 0.065, 0.39, 2.418, 0.4836, 2.9016, 0.286, 0.0572, 0.3432],[Tue Feb 22 09:00:00 GMT+01:00 2018, xxx, f8875453e5354d88931e3474021f723a, xxx, affiliate, 101723.0, ru, b4cb6e13bc1909b6f04f8cd44b1374d5, 0.5, 0.44, 3.72, 0.325, 0.065, 0.39, 2.418, 0.4836, 2.9016, 0.286, 0.0572, 0.3432],[Tue Feb 23 09:00:00 GMT+01:00 2018, xxx, f8875453e5354d88931e3474021f723a, xxx, affiliate, 101723.0, ru, b4cb6e13bc1909b6f04f8cd44b1374d5, 0.5, 0.44, 3.72, 0.325, 0.065, 0.39, 2.418, 0.4836, 2.9016, 0.286, 0.0572, 0.3432]]

What I want to achieve, but don't really know how, is to remove the entries in arr 1 that have the same dates as those in arr 2. Sp, considering the data presented above, all entries in arr will need to be removed, because their dates overlap with the entrie's dates in arr 2.

How can I do this? The entry number or other values shouldn't matter. If, e.g, in arr 1 I have 10k entries with date 5th of march and in arr 2 I have one single entry with the same date, I still want these 10k entries in arr 1 removed.

I tried to do this with filters, but since it's a 2d array I don't think this was the correct approach at all.

you perform check based on date only ?? or other fields also ? — Pranay Rana
– Pranay Rana, Commented Mar 13, 2018 at 12:06

gurvinder372 · Accepted Answer · 2018-03-13 12:18:08Z

4

Use map and filter.

Create a array of all dates in arr2

var allArr2Dates = arr2.map( s => s[0] );

And then filter arr1 using this array

arr1 = arr1.filter( s => allArr2Dates.includes( s[0] ) );

ES5 equivalent

var allArr2Dates = arr2.map( function(s){ return s[0]; } ); arr1 = arr1.filter( function(s) { return allArr2Dates.includes( s[0] ); } );

edited Mar 13, 2018 at 12:18

answered Mar 13, 2018 at 12:06

gurvinder372

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3 Comments

incense_stick Over a year ago

Hi, thanks for the reply. Actually i forgot to mention that I was doing it under ECMASCRIPT 5. Would you mind writing the EC5 version as well?

incense_stick Over a year ago

thanks for the edit! i am getting this error : TypeError: Cannot find function includes in object Tue Feb 20 2018 09:00:00 GMT+0100 (CET) Do you know why is that?

gurvinder372 Over a year ago

Use indexOf instead.

Jesus Cuesta · Accepted Answer · 2018-03-13 12:24:16Z

It is possible, mixed filter and every.

let one = [[1, 'aaa'], [2, 'bbb'], [3, '444']]; let second = [[14, 'aaa'], [2, 'bbb'], [6, 'ccc']]; const result = one.filter(data => second.every(dataAux => dataAux[0] !== data[0]));

Arman Charan · Accepted Answer · 2018-03-13 12:27:50Z

Map can be leveraged to overwrite related elements in key based Arrays.

See below for a practical example.

// Input. const array1 = [['Tue Feb 20 09:00:00 GMT+01:00 2018', 'A1'], ['Tue Feb 21 09:00:00 GMT+01:00 2018', 'A1'],['Tue Feb 22 09:00:00 GMT+01:00 2018', 'A1']] const array2 = [['Tue Feb 20 09:00:00 GMT+01:00 2018', 'A2'], ['Tue Feb 21 09:00:00 GMT+01:00 2018', 'A2'],['Tue Feb 22 09:00:00 GMT+01:00 2018', 'A2'],['Tue Feb 23 09:00:00 GMT+01:00 2018', 'A2']] // Output. const output = [...new Map([...array1, ...array2].map(day => [day[0], day])).values()] // Log. console.log(output)

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