void SaveRatings()
{
using (StreamWriter writer = new StreamWriter("../../../../data/user-ratings-" + current_user_id))
{
foreach (KeyValuePair <int, double> r in ratings)
{
writer.WriteLine("{0}\t{1}\t{2}",
user_mapping.ToOriginalID(current_user_id),
item_mapping.ToOriginalID(r.Key),
r.Value.ToString(CultureInfo.InvariantCulture));
}
}
}