How do I get the max data size of every column in an IQuerable using LINQ

public IEnumerable GetColumnSize(IQueryable source)
{
  var types = MapTypeToMembers(source).Select(x => x.Type);
  return types.Select(x => MapTypeToSize(x));
}

var lengths = from o in myObjectCollection
              select new
              {
                 PropertyLength1 = o.Property1.ToString().Length,
                 PropertyLength2 = o.Property2.ToString().Length,
                 ...
              }

var lengths = from o in myObjectCollection
              select o.ToString().Length;