Question

I have a List like this,

COL1  COL2  COL3
    ----  ----  -----
    AA    AB    Some text  
    AA    AC    Some text
    AA    AB    Some text
    AB    AB    Some text
    AB    AC    Some text
    AA    AC    Some text

I am looking for a fast and efficient logic in C# (perhaps in + LINQ) to remove duplicates in these two columns (COL1 , COL2 ) (Same like remove duplicates in Excel)

End result should be

AA  AB Some text
AA  AC Some text
AB  AB Some text
AB  AC Some text

Please advice

Answer 1

Use suggestion given by @Zerkms. For example, assuming your object type is MyRow:

public class MyRowComparer : IEqualityComparer<MyRow>
{
   public override bool Equals(MyRow r1, MyRow r2)
   {
      // adjust the logic as per your need e.g. case-insensitive etc
      return r1.Col1 == r2.Col1 && r1.Col2 == r2.Col2;
   }

   public override int GetHashCode(MyRow r)
   {
      // TODO: add null check etc
      return r.Col1.GetHashCode() ^ r.Col2.GetHashCode()
   }
}

IEnumerable<MyRow> myList = ...;
...
myList.Distinct(new MyRowComparer());