Find count each item in MultiDimensional List in vb.net?

Question

I have a class having 2 properties (both integers) and storing class into List collection.

Public Class GroupSelect
Public Property RowNo() As Integer
    Get
        Return m_RowNo
    End Get
    Set(ByVal value As Integer)
        m_RowNo = value
    End Set
End Property
Private m_RowNo As Integer
Public Property GroupNo() As Integer
    Get
        Return m_GroupNo
    End Get
    Set(ByVal value As Integer)
        m_GroupNo = value
    End Set
End Property
Private m_GroupNo As Integer
End Class

Ex:

RowNo     GroupNo
1          1
2          1
4          2

How to find each item in "GroupNo" has more than ONE TIME. In above example 2 is only one time, So return 'FALSE"

RowNo     GroupNo
1          1
2          1
4          2
5          2

Here I need return "TRUE". (values in "GroupNo" is not static and not in sort).

How can we do that in vb.net?

Answer 1

I might be misunderstanding, but does RowNo and GroupNo have a 1 to 1 relationship? Will index i of RowNo always be compared to index i of GroupNo? Do we even care about RowNo?

It sounds like the question you're asking is how to determine if an item in GroupNo is never repeated. Your first example shows 2 only once (which you want to return FALSE) and in the second it's shown twice (which you want to return TRUE).

If we can disregard the RowNo, a very simple way to determine if something is only listed once would be to sort GroupNo and then perform a loop and check index i with index i+1. You can keep a counter within the loop that counts the number of times that number is repeated. If index i is not equal to i+1 and the counter is at 1, you know that the number is never repeated.

Did I misinterpret the question?

Answer 2

So you want to the operation to return true if there are 2 or more RowNo values for every GroupNo otherwise return false? If that is correct then the following function will do that.

Note: Since you used the C# tag I feel like I have the green light to post code in C#.

public static bool HasTwoOrMoreInEachGroup(IEnumerable<GroupSelect> enumerable)
{
    var groups = new Dictionary<int, int>();
    foreach (GroupSelect item in enumerable)
    {
        int count = 0;
        if (groups.TryGetValue(item.GroupNo, out count))
        {
            groups[item.GroupNo] = count + 1;
        }
        else
        {
            groups.Add(item.GroupNo, 1);
        }
    }
    foreach (int count in groups.Values)
    {
        if (count <= 1)
        {
            return false;
        }
    }
    return true;
}

}

Or the Linq solution...

bool result = list.GroupBy(x => x.GroupNo).Where(x => x.Count() == 1).Count() >= 2;