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

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;