Hi, , how to get unique fields from a list of int string pair which contains duplicates

Question

1.00/5 (1 vote)

See more:

List<int,string> list = new List<int,string>();

//Example say, if the values in my list is

list[0] ={100, "abc"}
list[1] ={101, "zzz"}
list[2] ={103, "aaa"}
list[3] ={100, "yyy"}

//I want my list to return only unique values

//I want my list to return like this.

list={101,zzz;103,aaa};

What I have tried:

have used linq with Distinct() but it gives me non unique field with first occurrence.

Posted 18-Jan-18 13:13pm

Member 9845454

Updated 18-Jan-18 16:35pm

PIEBALDconsult

v2

Add a Solution

Comments

phil.o 18-Jan-18 20:11pm

Can you show the definition of your list variable, as well as the linq expression you have tried to use?
Please, do not reply to my comment, rather use the "Improve question" green widget and qualify your question with this relevant information.

2 solutions

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)

Graeme_Grant · Answer 1 · 2018-01-18T16:22:00

The List class does not support multiple dimensions. Read more about it here: <list> (C# Programming Guide) | Microsoft Docs[^]

If you want to use a List class, then you can use a Array, Class, [^]Tuple or KeyValuePair[^] to store your values. For this solution I will use the List<keyvaluepair> as you have non-unique keys. The Dictionary[^] class requires unique keys so is not suitable.

C#

var list = new List<KeyValuePair<int, string>>
{
    new KeyValuePair<int, string> (100, "abc"),
    new KeyValuePair<int, string> (101, "zzz"),
    new KeyValuePair<int, string> (103, "aaa"),
    new KeyValuePair<int, string>(100, "yyy")
};

var results = list.GroupBy(x => x.Key)
                    .Where(x => x.Count() == 1)
                    .Select(x => x.First());

foreach (var item in results)
{
    Console.WriteLine($"Key: {item.Key}  Value: {item.Value}");
}

The Linq expression will group by the Key field, when where there is only 1 unique result per grouping, select the first entry.

Karthik_Mahalingam · Answer 2 · 2018-01-18T16:35:00

Solution 2

try

List<KeyValuePair<int, string>> lst = new List<KeyValuePair<int, string>>();
        lst.Add(new KeyValuePair<int, string>(100, "abc"));
        lst.Add(new KeyValuePair<int, string>(101, "zzz"));
        lst.Add(new KeyValuePair<int, string>(103, "aaa"));
        lst.Add(new KeyValuePair<int, string>(100, "yyy"));

       
       int[] uniqueItems = lst.GroupBy(k => k.Key).Where(k => k.Count() == 1).Select(k => k.Key).ToArray();
       lst = lst.Where(k => uniqueItems.Contains(k.Key)).ToList();  //list={101,zzz;103,aaa};

Posted 18-Jan-18 16:35pm

Karthik_Mahalingam

Updated 18-Jan-18 16:39pm

Comments

Graeme_Grant 18-Jan-18 23:40pm

Almost looks identical...

Karthik_Mahalingam 19-Jan-18 0:34am

when i was about to post the solution, this thread had no solutions and took some break and posted the solution and i saw your your solution.
however mine is a lengthy process (for better understanding to op) , by getting the unique ids and filtering the main collection.