/// <summary>Rate a given set of instances and write it to a TextWriter</summary>
/// <param name="recommender">rating predictor</param>
/// <param name="ratings">test cases</param>
/// <param name="writer">the TextWriter to write the predictions to</param>
/// <param name="user_mapping">an <see cref="Mapping"/> object for the user IDs</param>
/// <param name="item_mapping">an <see cref="Mapping"/> object for the item IDs</param>
/// <param name="line_format">a format string specifying the line format; {0} is the user ID, {1} the item ID, {2} the rating</param>
/// <param name="header">if specified, write this string at the start of the output</param>
public static void WritePredictions(
this IRecommender recommender,
IRatings ratings,
TextWriter writer,
IMapping user_mapping = null,
IMapping item_mapping = null,
string line_format = "{0}\t{1}\t{2}",
string header = null)
{
if (user_mapping == null)
{
user_mapping = new IdentityMapping();
}
if (item_mapping == null)
{
item_mapping = new IdentityMapping();
}
if (header != null)
{
writer.WriteLine(header);
}
if (line_format == "ranking")
{
foreach (int user_id in ratings.AllUsers)
{
if (ratings.ByUser[user_id].Count > 0)
{
recommender.WritePredictions(
user_id,
new List <int>(from index in ratings.ByUser[user_id] select ratings.Items[index]),
new int[] { },
ratings.ByUser[user_id].Count,
writer,
user_mapping, item_mapping);
}
}
}
else
{
for (int index = 0; index < ratings.Count; index++)
{
writer.WriteLine(
string.Format(
CultureInfo.InvariantCulture,
line_format,
user_mapping.ToOriginalID(ratings.Users[index]),
item_mapping.ToOriginalID(ratings.Items[index]),
recommender.Predict(ratings.Users[index], ratings.Items[index])
)
);
}
}
}
