lambda expression C# to get the unmatched record from a List

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Hi,

I have a list1 = {1,1,2,3,4,5}

I want to compare the items in the list.

My code:
var list2 = list1.GroupBy(c => c.action).Select(g => g.FirstOrDefault()).ToList();

Now i have a new list2 = {1,1,2}
i want to get a 2 out of this list.

or if List ={1,1}
I want to get 1 out of it.

Any suggestions, please?

Posted 14-May-13 3:04am

rohit24c

Updated 15-May-13 19:19pm

v4

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Sergey Alexandrovich Kryukov 14-May-13 12:11pm

Your language? (No, I don't want to take a guess.)
—SA

2 solutions

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OriginalGriff · Answer 1 · 2013-05-15T21:01:00

Solution 1

You don't need a lambda - just use Linq methods:

C#

List<int> list1 = new int[] { 1, 1, 2, 3, 4, 5 }.ToList();
List<int> list2 = new int[] { 1, 1, 2 }.ToList();


var result = list1.Intersect(list2);
foreach (int i in result) Console.WriteLine(i);

Posted 15-May-13 21:01pm

OriginalGriff

Comments

rohit24c 16-May-13 3:11am

I need to get the items for a List if it occurs 1 in the List
List= {1,1,2}

i need 2 from the list as it occurs once.

OriginalGriff 16-May-13 3:26am

AH! You need to explain your needs better - remember we can't see your screen or access your HDD...
Try:
int i = list1.Intersect(list2).Count();

Andre T.G. · Answer 2 · 2013-05-18T14:09:00

C#

int[] arr = new int[] { 1, 1, 2 };
//Create a dictionary where the key is each int occurance
//and the value is the number of int occurances.
Dictionary<int, int> dict = arr.Distinct().ToDictionary(i => i, i => arr.Where(ii=>ii==i).Count());
//now do what you like with it.. 
//eg get me the value that occurs least often, 
//which I think is what you're after:
int r=dict[dict.Values.Min()];

ATG