How remove items who is only one in List?

Question

5.00/5 (1 vote)

See more:

Hi
I would like get data from list, which is used more time.
e.g. I have a list who contains items 1,2,5,2,8,7,8,2
I want only item who is more time 2,2,8,8,2

Is for this some method or?

I create my way this...
foreach and List.Contains and last step add to new List.

Thank you

Posted 26-Nov-14 22:45pm

smoula99

Add a Solution

5 solutions

Solution 5

Hello ,
Even Try The Following

C#

List<int> list = new List<int>() { 1, 3, 3, 4, 5, 6, 6, 7, 8 };
var x = list.GroupBy(x=>x).FirstOrDefault(g=>g.Count()>1).Key;//C#3

Posted 27-Nov-14 0:39am

Neetin_1809

Updated 27-Nov-14 1:17am

v2

Solution 4

Hi
Thank you for quickly solution

Posted 26-Nov-14 23:07pm

smoula99

Comments

Afzaal Ahmad Zeeshan 27-Nov-14 5:28am

You should always post things like this as comments to the post and not as answers. :-)

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2014-11-26T23:04:00

Since you tagged as LINQ, here is a LINQ method solution:

C#

            List<int> data = "1,2,5,2,8,7,8,2".Split(',').Select(s => int.Parse(s)).ToList();  //Setup input list

            List<int> repeats = data.GroupBy(i => i).Where(g => g.Count() != 1).Select(g => g.Key).ToList(); // So it's done once only.
            List<int> duplicates = data.Where(i => repeats.Contains(i)).ToList();

            foreach (int i in duplicates) Console.WriteLine(i);
</int>

Marcin Kozub · Accepted Answer · 2014-11-26T22:55:00

Solution 2

Hello,

C#

var input = new List<int>() { 1, 2, 5, 2, 8, 7, 8, 2 };
var output = (from x in input
                where input.Count(c => c == x) > 1
                select x).ToList();

Console.WriteLine(string.Join(", ", input));
Console.WriteLine(string.Join(", ", output));

I hope it help you.

Posted 26-Nov-14 22:55pm

Marcin Kozub

Updated 26-Nov-14 22:57pm

v3

Afzaal Ahmad Zeeshan · Accepted Answer · 2014-11-26T22:53:00

Try this code, it would work for you to get the only elements that are duplicated in the List.

C#

// example list that I tried in my IDE, write your own list here
List<int> list = new List<int>() { 1, 3, 3, 4, 5, 6, 6, 7, 8 };
// run the loop
foreach (int i in list.GroupBy(s => s)
                  .SelectMany(grp => grp.Skip(1)))
{
   // print each element, you can do any other task on it too
   Console.WriteLine(i);
}

.. this will provide you with the only elements that are distinct. In the above context 3 and 6 were printed on screen.