Subtract array of objects from array of objects

Question

I know similar questions have been posted but they never seems to target the same problem.

I want to remove Objects contained in the second array (itemsToRemove) from the first array (allItems).

allItems = [{x:1, y:2}, {x:1, y:1}, {x:4, y:1}]

itemsToRemove = [{x:1, y:2}]

result = [{x:1, y:1}, {x:4, y:1}]

I've tried many ways, but it somehow fails at the find() condition

      const result = allItems.filter((itemFromAllItems ) => {
                return !itemsToRemove.find( itemToRemove => {
                    return itemFromAllItems.x === itemToRemove.x && itemFromAllItems.y === itemToRemove.y
                })
            })

can anyone please look at my answer and downvoting it with explanation of why it is wrong !! — Sven.hig
– Sven.hig, Commented Jul 8, 2020 at 19:22

Ashik Paul · Accepted Answer · 2020-07-08 18:38:44Z

1

Assuming that your objects only have x and y values, This will work.

var allItems = [{x:1, y:2}, {x:1, y:1}, {x:4, y:1}]

var itemsToRemove = [{x:1, y:2}]

var result = allItems.filter(e => !itemsToRemove.some(s => s.x === e.x && s.y === e.y));

console.log(result);

Hope this helps

edited Jul 8, 2020 at 18:38

answered Jul 8, 2020 at 18:34

Ashik Paul

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5 Comments

baao Over a year ago

Assuming they want to code. What would be a generic solution?

Ashik Paul Over a year ago

Sorry, I don't know how to make this dynamic

Telmo Trooper Over a year ago

You can just replace result with allItems if you want allItems to be changed. E.g. var allItems = allItems.filter(e => !itemsToRemove.some(s => s.x === e.x && s.y === e.y));

Ashik Paul Over a year ago

@Philx94 Sorry, I didn't get you. Could you please explain?

Philx94 Over a year ago

Sorry, I'm having a hard time figuring why it is not working on my end. I'll be back.

Sven.hig · Accepted Answer · 2020-07-08 19:02:03Z

1

If you simply want to filter you can use filter and some to get the data you want however if you want to literally remove the object from the array you can use this instead

allItems = [{x:1, y:2}, {x:1, y:1}, {x:4, y:1},{x:4, y:1},{x:4, y:1}]
itemsToRemove = [{x:1, y:2},{x:4, y:1}]
 for(let i=0;i<allItems.length;i++){
   o=allItems[i]
  itemsToRemove.some(v=>{if(o.x==v.x &&o.y==v.y) allItems.splice(i,1),i--})
 }
console.log(allItems)

edited Jul 8, 2020 at 19:02

answered Jul 8, 2020 at 18:56

Sven.hig

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7 Comments

Sven.hig Over a year ago

Why is the downvote!!! why??? what is wrong with this response please I am interested to know, I am addressing the person who downvoted the answer, I am open to criticism show me what is the problem with this answer

Sven.hig Over a year ago

Please remember before downvoting an answer that the auther made some effort to write an answer and unless the answer is very poor and bad or out of context it makes no sense to downvote it without at least providing an explanation

baumli Over a year ago

When I test this, I'm only getting this as a result: 0: Object { x: 1, y: 1 }

Sven.hig Over a year ago

Yes because i used a different example (data) from the one used above, i added more data to stress the fact that this solution works even for same objects

Sven.hig Over a year ago

@baumli You can test the code with the data provided above and it works as well

|

baumli · Accepted Answer · 2020-07-08 19:34:08Z

0

This takes the 2 arrays, compares the values, and makes a new one with only the results that don't match.

<script>
allItems = [{x:1, y:2}, {x:1, y:1}, {x:4, y:1}];
itemsToRemove = [{x:1, y:2}]
result = [];
for(var i = 0; i < allItems.length; i++){
  for(var j = 0; j < itemsToRemove.length; j++){ 
    if(JSON.stringify(allItems[i]) !== JSON.stringify(itemsToRemove[j])){
      result.push(allItems[i]);
    }
  }
} 
console.log(result);
</script>

edited Jul 8, 2020 at 19:34

answered Jul 8, 2020 at 19:15

baumli

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