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Ilan
Ilan

Reputation: 999

How to delete objects from array using LINQ

I have an array of objects of type A: A[] ar. And a list of integers: List<int> indexes.

How can I delete from the ar all objects with indexes in the indexes, using LINQ? I.e. I need a new (smaller) array without the objects that their indexes are in indexes. Using LINQ.

Is the order of the remained objects will be the same as before the deletion?

Thanks a lot.

Upvotes: 0

Views: 1514

Answers (2)

Richard
Richard

Reputation: 108975

You cannot modify an array only the elements it contains.

But you can easily create a replacement array:

myArray = myArray.Where(x => x.KeepThisElement).ToArray();

With LINQ to Objects (which you'll be using in this case) there in an overload of Where that passes the current index to the predicate:

myArray = myArray.Where((x, idx) => !indexes.Conatins(idx)).ToArray();

Upvotes: 2

opewix
opewix

Reputation: 5083

This may look odd, but it does what you want (it's not a LINQ):

var filtered = new List<A>();
for (var i = 0; i < ar.Length; i++)
{
    if (indexes.Contains(i))
        continue;

    filtered.Add(ar[i]]);
}

var ar = filtered.ToArray();

If your integer list is very big, consider to use HashSet<int> instead of list to get more performance

Upvotes: 1

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