Find intersection and remove in a list

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Hello all,

I had the following code which works fine but I am looking for a finer solution.
====EDIT====
My Items in the lists are ;
NewContainsExistingMemberInDialog: "B", "C", "D", "E"
DialogAdditionDistinct: "A", "B", "C"

Final output:
IntersectedAndRemovedList which is DialogAdditionDistinct. It should only contain "A".

============

C#

List<int> ItemsToBeDeletedAtIndex = new List<int>();
                        int index = -1;

                        foreach (string itemCAD in DialogAdditionDistinct)
                        {
                            index++;
                            foreach (string itemNCEMID in NewContainsExistingMemberInDialog)
                            {
                                if (itemNCEMID == itemCAD)
                                {
                                    ItemsToBeDeletedAtIndex.Add(index);
                                }
                            }
                        }

                        int indexCounter = 0;
                        foreach (int itemIndex in ItemsToBeDeletedAtIndex)
                        {
                            DialogAdditionDistinct.RemoveAt(itemIndex - indexCounter);
                            indexCounter++;
                        }

What this code does finds the same items between the two list and saves the index of the item. After that removing the items in the matching index.

So basically is there a LINQ code or much optimized code version of this finding the intersection between two list and removing the intersected items from one of the list.

Thank you very much for your time and understanding.

Posted 21-Jan-13 21:55pm

wonder-FOOL

Updated 21-Jan-13 22:37pm

v2

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5 solutions

Solution 1

C#

foreach (string itemNCEMID in NewContainsExistingMemberInDialog)
                        {
                             if (DialogAdditionDistinct.Any(accEntity => accEntity.Equals(itemNCEMID )))
                            {
                                DialogAdditionDistinct.Remove(n);

                            }
                       }

Posted 21-Jan-13 22:12pm

josh-jw

v2

Solution 2

There is the Except method in LINQ and in your example should be used in the following way.

C#

List<string> a = new List<string>() { "A", "B", "C", "D" };
List<string> b = new List<string>() { "A", "B", "E", "F" };

List<string> c = a.Except(b).ToList<string>();

What you will find in the list c are two elements, C and D, the once that are contained in the list a and not in the list b.

By searching on google you will find more examples.

Cheers

EDIT:
Based on new information this is a possible solution:

C#

List<string> a = new List<string>() { "B", "C", "D", "E" };
List<string> b = new List<string>() { "A", "B", "C" };

a = b.Except(a).ToList<string>();

Cheers

Posted 21-Jan-13 22:16pm

Mario Majčica

Updated 21-Jan-13 23:00pm

v2

Comments

wonder-FOOL 22-Jan-13 4:20am

Thank you for your answer but I have already knew the Except method but I couldnt find a way to remove the items between the list that I want the items to be removed and the items that is intersected.

Mario Majčica 22-Jan-13 4:22am

Can you make an example of the items in collection A and items in collection B together with the result you are expecting? It is not clear by your code. Then we can study a correct LINQ statement that will do. Cheers

wonder-FOOL 22-Jan-13 4:37am

Ok I have updated my question. I hope that clears it out.

wonder-FOOL 22-Jan-13 4:44am

Thanks but I have found it with a much simplier and optimized way. I have provided it as a solution.

Mario Majčica 22-Jan-13 5:00am

Based on your edit, check mine. Cheers

Solution 3

I think this code will work in your case.

DialogAdditionDistinct = DialogAdditionDistinct.Except( NewContainsExistingMemberInDialog).ToList();

Posted 21-Jan-13 22:31pm

napster_ashish

Updated 21-Jan-13 22:34pm

v3

Solution 5

well i don't know why you need to remove the items instead of creating a new list without it...

in any case that should work

SQL

DialogAdditionDistinct.Where(i => NewContainsExistingMemberInDialog.Contains(i)).ToList().ForEach(j => DialogAdditionDistinct.Remove(j));

your DialogAdditionDistinct will be as you need

Posted 21-Jan-13 22:53pm

nrgjack

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wonder-FOOL · Accepted Answer · 2013-01-21T22:43:00

Solution 4

OK I have found it thanks for the replies all.

C#

foreach (var p in DialogAdditionDistinct.Intersect(NewContainsExistingMemberInDialog).ToList())
                            DialogAdditionDistinct.Remove(p);

Posted 21-Jan-13 22:43pm

wonder-FOOL