With C1CollectionView you can filter a collection to produce a new sub-set containing exactly those elements of the original collection for which a given predicate returns true. When you filter a C1CollectionView, the underlying data set is not affected. The Filter property gets or sets a callback used to determine if an item is suitable for inclusion in the view.

For example, you can set a predicate to the Filter property and this will cause the list to be filtered by that predicate.

' create an observable list of customers
Dim list = New System.Collections.ObjectModel.ObservableCollection(Of Customer)()

' create a C1CollectionView from the list
_view = New C1.Xaml.C1CollectionView(list)

' filter by country = Austria. Customers not from Austria will be filtered out.
_view.Filter = Sub(item As Object)
Dim c As Customer = TryCast(item, Customer)
If c IsNot Nothing Then
      If c.Country.Equals("Austria") Then
            Return True
      End If
End If
Return False
End Sub

// create an observable list of customers
var list = new System.Collections.ObjectModel.ObservableCollection<Customer>();

// create a C1CollectionView from the list
_view = new C1.Xaml.C1CollectionView(list);

// filter by country = Austria. Customers not from Austria will be filtered out.
_view.Filter = delegate(object item)
{
    Customer c = item as Customer;
    if (c != null)
    {
        if (c.Country.Equals("Austria"))
            return true;
    }
    return false;
};

For an advanced example of filtering, see the Filter sample for FlexGrid for UWP: https://developer.mescius.com/samples.