Linq: group items that have equal elements > 200

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I'm using the below code to determine the number of equal elements in two lists (x of 256):

C#

List<string> secretData1 = new List<string>() { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple" };
    List<string> secretData2 = new List<string>() { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","apple","orange","orange","apple","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange" };
    
    int equalElements = secretData1.Zip(secretData2, (i, j) => i == j).Count(eq => eq);     
    Console.WriteLine(equalElements);

Equal Elements (Output): 114

Now, I want to convert this code on a larger scale for a single list.

C#

public class SecretAgents
{
    public string Name {get; set;}
    public List<string> SecretData {get; set;}
    public int GroupID {get; set;}
}

    List<SecretAgents> secretAgents = new List<SecretAgents>();
    
    secretAgents.Add(new SecretAgents { Name= "SecretAgent 1", GroupID= 0, SecretData= new List<string> { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple" } });
    secretAgents.Add(new SecretAgents { Name= "SecretAgent 2", GroupID= 0, SecretData= new List<string> { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","apple","orange","orange","apple","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange" } });
    secretAgents.Add(new SecretAgents { Name= "SecretAgent 3", GroupID= 0, SecretData= new List<string> { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple" } });
    secretAgents.Add(new SecretAgents { Name= "SecretAgent 4", GroupID= 0, SecretData= new List<string> { "orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","apple","orange","orange","apple","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","orange","orange","orange","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","apple","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange","apple","orange","orange","orange","orange","apple","apple","orange","orange","orange","orange","orange","orange","orange","orange","orange"} });
    secretAgents.Add(new SecretAgents { Name= "SecretAgent 5", GroupID= 0, SecretData= new List<string> { "apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","apple","orange","orange","apple","apple","apple","apple","apple","apple"} });

I want to group SecretAgents that have equal elements > 200.

Expected Output:

C#

Group 1: SecretAgent 1 & SecretAgent 3 (Reason: Equal elements: 248)
    Group 2: SecretAgent 2 & SecretAgent 4 (Reason: Equal elements: 256)
    Group 3: SecretAgent 5

Any help is appreciated.

What I have tried:

First code in the question (.Zip)

Posted 2-Sep-22 15:02pm

Cat Lover

Updated 3-Sep-22 4:44am

v2

Add a Solution

2 solutions

Solution 2

I suggest that you adopt a simple approach. Something like:

C#

//iterate over all possible matches and set each agents GroupId to the max value found
  for(int i=0;i<secretAgents.Count-1;i++)
   {
     for(int j=i+1;j<secretAgents.Count;j++)
      {
        var matchesCount = secretAgents[i].SecretData.Zip(secretAgents[j].SecretData, 
                                          (x, y) => x == y).Count(b => b == true); 
        if (matchesCount > secretAgents[i].GroupID) secretAgents[i].GroupID = matchesCount;
        if (matchesCount > secretAgents[j].GroupID) secretAgents[j].GroupID = matchesCount;
      }
    }
   //select the groups using the GroupID as the key and >200 as the filter
     var groups = secretAgents.Where(a => a.GroupID > 200).GroupBy(a => a.GroupID);
   //output the results
     foreach(var grp in groups)
      {
        Console.WriteLine($"GroupId={grp.Key}, Members {string.Join(", ", grp.Select(a => a.Name))}");
        //prints:GroupId=248, Members SecretAgent 1, SecretAgent 3
        //GroupId = 256, Members SecretAgent 2, SecretAgent 4
      }

Posted 3-Sep-22 4:44am

George Swan

Comments

Cat Lover 4-Sep-22 3:10am

There appears to be no problem. Kindly ignore my previous comment. Thank you!

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Graeme_Grant · Accepted Answer · 2022-09-02T16:17:00

[UPDATE #2]

Okay, I have redone the code in Linq Query Syntax and broken down each step to make it:
1. easier to read & debug
2. easier to maintain

I have also moved your comparer to an inline method. It can be moved to a normal method.

C#

int minCount = 150;

int MyComparer(SecretAgents secretAgent1, SecretAgents secretAgent2)
{
    var result = secretAgent1.SecretData.Zip(secretAgent2.SecretData, (i, j) => i == j);
    var count = result.Count(eq => eq);

    Console.WriteLine($".... {secretAgents.IndexOf(secretAgent1)} <> {secretAgents.IndexOf(secretAgent2)} = {count}");

    return count;
}

Console.WriteLine("1. Manual Comparison");
var equalElements = new List<int>
{
    MyComparer(secretAgents[0], secretAgents[1]),
    MyComparer(secretAgents[0], secretAgents[2]),
    MyComparer(secretAgents[0], secretAgents[3]),
    MyComparer(secretAgents[0], secretAgents[4]),
    MyComparer(secretAgents[1], secretAgents[2]),
    MyComparer(secretAgents[1], secretAgents[3]),
    MyComparer(secretAgents[1], secretAgents[4]),
    MyComparer(secretAgents[2], secretAgents[3]),
    MyComparer(secretAgents[2], secretAgents[4]),
    MyComparer(secretAgents[3], secretAgents[4]),
};

Console.WriteLine();
Console.WriteLine("--");
Console.WriteLine();

Console.WriteLine("2. Linq Filter");

var groups = from secretAgent in secretAgents
    group secretAgent by secretAgent.GroupID;

var filtered = from grp in groups
    from leftAgent in grp
    from rightAgent in grp
    where leftAgent != rightAgent &&
          grp.ToList().IndexOf(leftAgent) < grp.ToList().IndexOf(rightAgent) &&
          MyComparer(leftAgent, rightAgent) > minCount
    select (grp.Key, leftAgent, rightAgent);

var formatted = filtered
    .GroupBy(x => x.Key)
    .SelectMany(group => group
        .Select(item =>
        {
            var count = MyComparer(item.leftAgent, item.rightAgent);
            return
                $"Group {group.Key}: {item.leftAgent.Name} & {item.rightAgent.Name} (reason: Equal elements: {count})";
        })
    );

foreach (string equalElement in formatted)
{
    Console.WriteLine(equalElement);
}

and the output, with debug output:

1. Manual Comparison
.... 0 <> 1 = 114
.... 0 <> 2 = 248
.... 0 <> 3 = 114
.... 0 <> 4 = 156
.... 1 <> 2 = 112
.... 1 <> 3 = 256
.... 1 <> 4 = 82
.... 2 <> 3 = 112
.... 2 <> 4 = 156
.... 3 <> 4 = 82

--

2. Linq Filter
.... 0 <> 1 = 114
.... 0 <> 2 = 248
.... 0 <> 3 = 114
.... 0 <> 4 = 156
.... 1 <> 2 = 112
.... 1 <> 3 = 256
.... 1 <> 4 = 82
.... 2 <> 3 = 112
.... 2 <> 4 = 156
.... 3 <> 4 = 82
.... 0 <> 2 = 248
Group 0: SecretAgent 1 & SecretAgent 3 (reason: Equal elements: 248)
.... 0 <> 4 = 156
Group 0: SecretAgent 1 & SecretAgent 5 (reason: Equal elements: 156)
.... 1 <> 3 = 256
Group 0: SecretAgent 2 & SecretAgent 4 (reason: Equal elements: 256)
.... 2 <> 4 = 156
Group 0: SecretAgent 3 & SecretAgent 5 (reason: Equal elements: 156)

Enjoy!