/// <summary>Evaluates a rating predictor for RMSE, (N)MAE, and CBD</summary>
/// <remarks>
/// <para>
/// See http://recsyswiki.com/wiki/Root_mean_square_error and http://recsyswiki.com/wiki/Mean_absolute_error
/// </para>
/// <para>
/// For NMAE, see the paper by Goldberg et al.
/// </para>
/// <para>
/// For CBD (capped binomial deviance), see http://www.kaggle.com/c/ChessRatings2/Details/Evaluation
/// </para>
/// <para>
/// If the recommender can take time into account, and the rating dataset provides rating times,
/// this information will be used for making rating predictions.
/// </para>
/// <para>
/// Literature:
/// <list type="bullet">
/// <item><description>
/// Ken Goldberg, Theresa Roeder, Dhruv Gupta, and Chris Perkins:
/// Eigentaste: A Constant Time Collaborative Filtering Algorithm.
/// nformation Retrieval Journal 2001.
/// http://goldberg.berkeley.edu/pubs/eigentaste.pdf
/// </description></item>
/// </list>
/// </para>
/// </remarks>
/// <param name="recommender">rating predictor</param>
/// <param name="test_ratings">test cases</param>
/// <param name="training_ratings">the training examples</param>
/// <returns>a Dictionary containing the evaluation results</returns>
static public RatingPredictionEvaluationResults Evaluate(this IRatingPredictor recommender, IRatings test_ratings, IRatings training_ratings = null)
{
if (recommender == null)
{
throw new ArgumentNullException("recommender");
}
if (test_ratings == null)
{
throw new ArgumentNullException("ratings");
}
var all_indices = Enumerable.Range(0, test_ratings.Count).ToArray();
var results = new RatingPredictionEvaluationResults(Evaluate(recommender, test_ratings, all_indices));
if (training_ratings != null)
{
var new_user_indices = (from index in all_indices
where test_ratings.Users[index] > training_ratings.MaxUserID || training_ratings.CountByUser[test_ratings.Users[index]] == 0
select index).ToArray();
results.NewUserResults = Evaluate(recommender, test_ratings, new_user_indices);
var new_item_indices = (from index in all_indices
where test_ratings.Items[index] > training_ratings.MaxItemID || training_ratings.CountByItem[test_ratings.Items[index]] == 0 select index).ToArray();
results.NewItemResults = Evaluate(recommender, test_ratings, new_item_indices);
results.NewUserNewItemResults = Evaluate(recommender, test_ratings, Enumerable.Intersect(new_user_indices, new_item_indices).ToArray());
}
return(results);
}
/// <summary>Evaluate on the folds of a dataset split</summary>
/// <param name="recommender">a rating predictor</param>
/// <param name="split">a rating dataset split</param>
/// <param name="compute_fit">if set to true measure fit on the training data as well</param>
/// <param name="show_fold_results">set to true to print per-fold results to STDERR</param>
/// <returns>a dictionary containing the average results over the different folds of the split</returns>
public static RatingPredictionEvaluationResults DoCrossValidation(
this RatingPredictor recommender,
ISplit<IRatings> split,
bool compute_fit = false,
bool show_fold_results = false)
{
var fold_results = new RatingPredictionEvaluationResults[split.NumberOfFolds];
Parallel.For(0, (int) split.NumberOfFolds, i =>
{
try
{
var split_recommender = (RatingPredictor) recommender.Clone(); // to avoid changes in recommender
split_recommender.Ratings = split.Train[i];
if (recommender is ITransductiveRatingPredictor)
((ITransductiveRatingPredictor) split_recommender).AdditionalFeedback = split.Test[i];
split_recommender.Train();
fold_results[i] = Ratings.Evaluate(split_recommender, split.Test[i]);
if (compute_fit)
fold_results[i]["fit"] = (float) split_recommender.ComputeFit();
if (show_fold_results)
Console.Error.WriteLine("fold {0} {1}", i, fold_results[i]);
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw e;
}
});
return new RatingPredictionEvaluationResults(fold_results);
}
/// <summary>Performs user-wise fold-in evaluation, but instead of folding in perform incremental training with the new data</summary>
/// <remarks>
/// </remarks>
/// <returns>the evaluation results</returns>
/// <param name='recommender'>a rating predictor capable of performing a user fold-in</param>
/// <param name='update_data'>the rating data used to represent the users</param>
/// <param name='eval_data'>the evaluation data</param>
static public RatingPredictionEvaluationResults EvaluateFoldInIncrementalTraining(this IncrementalRatingPredictor recommender, IRatings update_data, IRatings eval_data)
{
double rmse = 0;
double mae = 0;
double cbd = 0;
int rating_count = 0;
foreach (int user_id in update_data.AllUsers)
{
if (eval_data.AllUsers.Contains(user_id))
{
var local_recommender = (IncrementalRatingPredictor)recommender.Clone();
// add ratings and perform incremental training
var user_ratings = new RatingsProxy(update_data, update_data.ByUser[user_id]);
local_recommender.AddRatings(user_ratings);
var items_to_rate = (from index in eval_data.ByUser[user_id] select eval_data.Items[index]).ToArray();
var predicted_ratings = recommender.Recommend(user_id, candidate_items: items_to_rate);
foreach (var pred in predicted_ratings)
{
float prediction = pred.Item2;
float actual_rating = eval_data.Get(user_id, pred.Item1, eval_data.ByUser[user_id]);
float error = prediction - actual_rating;
rmse += error * error;
mae += Math.Abs(error);
cbd += Eval.Ratings.ComputeCBD(actual_rating, prediction, recommender.MinRating, recommender.MaxRating);
rating_count++;
}
// remove ratings again
local_recommender.RemoveRatings(user_ratings);
Console.Error.Write(".");
}
}
mae = mae / rating_count;
rmse = Math.Sqrt(rmse / rating_count);
cbd = cbd / rating_count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float)rmse;
result["MAE"] = (float)mae;
result["NMAE"] = (float)mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float)cbd;
return(result);
}
/// <summary>Performs user-wise fold-in evaluation</summary>
/// <returns>the evaluation results</returns>
/// <param name='recommender'>a rating predictor capable of performing a user fold-in</param>
/// <param name='update_data'>the rating data used to represent the users</param>
/// <param name='eval_data'>the evaluation data</param>
static public RatingPredictionEvaluationResults EvaluateFoldIn(this IFoldInRatingPredictor recommender, IRatings update_data, IRatings eval_data)
{
double rmse = 0;
double mae = 0;
double cbd = 0;
int rating_count = 0;
foreach (int user_id in update_data.AllUsers)
{
if (eval_data.AllUsers.Contains(user_id))
{
var known_ratings = (
from index in update_data.ByUser[user_id]
select Tuple.Create(update_data.Items[index], update_data[index])
).ToArray();
var items_to_rate = (from index in eval_data.ByUser[user_id] select eval_data.Items[index]).ToArray();
var predicted_ratings = recommender.ScoreItems(known_ratings, items_to_rate);
foreach (var pred in predicted_ratings)
{
float prediction = pred.Item2;
float actual_rating = eval_data.Get(user_id, pred.Item1, eval_data.ByUser[user_id]);
float error = prediction - actual_rating;
rmse += error * error;
mae += Math.Abs(error);
cbd += Eval.Ratings.ComputeCBD(actual_rating, prediction, recommender.MinRating, recommender.MaxRating);
rating_count++;
}
Console.Error.Write(".");
}
}
mae = mae / rating_count;
rmse = Math.Sqrt(rmse / rating_count);
cbd = cbd / rating_count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float)rmse;
result["MAE"] = (float)mae;
result["NMAE"] = (float)mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float)cbd;
return(result);
}
/// <summary>Evaluate on the folds of a dataset split</summary>
/// <param name="recommender">a rating predictor</param>
/// <param name="split">a rating dataset split</param>
/// <param name="compute_fit">if set to true measure fit on the training data as well</param>
/// <param name="show_results">set to true to print results to STDERR</param>
/// <returns>a dictionary containing the average results over the different folds of the split</returns>
public static RatingPredictionEvaluationResults DoCrossValidation(
this RatingPredictor recommender,
ISplit<IRatings> split,
bool compute_fit = false,
bool show_results = false)
{
var avg_results = new RatingPredictionEvaluationResults();
Parallel.For(0, (int) split.NumberOfFolds, i =>
{
try
{
var split_recommender = (RatingPredictor) recommender.Clone(); // to avoid changes in recommender
split_recommender.Ratings = split.Train[i];
if (recommender is ITransductiveRatingPredictor)
((ITransductiveRatingPredictor) split_recommender).AdditionalFeedback = split.Test[i];
split_recommender.Train();
var fold_results = Ratings.Evaluate(split_recommender, split.Test[i]);
if (compute_fit)
fold_results["fit"] = (float) split_recommender.ComputeFit();
// thread-safe stats
lock (avg_results)
foreach (var key in fold_results.Keys)
if (avg_results.ContainsKey(key))
avg_results[key] += fold_results[key];
else
avg_results[key] = fold_results[key];
if (show_results)
Console.Error.WriteLine("fold {0} {1}", i, fold_results);
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw e;
}
});
foreach (var key in Ratings.Measures)
avg_results[key] /= split.NumberOfFolds;
return avg_results;
}
/// <summary>Performs user-wise fold-in evaluation</summary>
/// <returns>the evaluation results</returns>
/// <param name='recommender'>a rating predictor capable of performing a user fold-in</param>
/// <param name='update_data'>the rating data used to represent the users</param>
/// <param name='eval_data'>the evaluation data</param>
static public RatingPredictionEvaluationResults EvaluateFoldIn(this IFoldInRatingPredictor recommender, IRatings update_data, IRatings eval_data)
{
double rmse = 0;
double mae = 0;
double cbd = 0;
int rating_count = 0;
foreach (int user_id in update_data.AllUsers)
if (eval_data.AllUsers.Contains(user_id))
{
var known_ratings = (
from index in update_data.ByUser[user_id]
select Tuple.Create(update_data.Items[index], update_data[index])
).ToArray();
var items_to_rate = (from index in eval_data.ByUser[user_id] select eval_data.Items[index]).ToArray();
var predicted_ratings = recommender.ScoreItems(known_ratings, items_to_rate);
foreach (var pred in predicted_ratings)
{
float prediction = pred.Item2;
float actual_rating = eval_data.Get(user_id, pred.Item1, eval_data.ByUser[user_id]);
float error = prediction - actual_rating;
rmse += error * error;
mae += Math.Abs(error);
cbd += Eval.Ratings.ComputeCBD(actual_rating, prediction, recommender.MinRating, recommender.MaxRating);
rating_count++;
}
Console.Error.Write(".");
}
mae = mae / rating_count;
rmse = Math.Sqrt(rmse / rating_count);
cbd = cbd / rating_count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float) rmse;
result["MAE"] = (float) mae;
result["NMAE"] = (float) mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float) cbd;
return result;
}
/// <summary>Evaluate on the folds of a dataset split</summary>
/// <param name="recommender">a rating predictor</param>
/// <param name="split">a rating dataset split</param>
/// <param name="compute_fit">if set to true measure fit on the training data as well</param>
/// <param name="show_fold_results">set to true to print per-fold results to STDERR</param>
/// <returns>a dictionary containing the average results over the different folds of the split</returns>
static public RatingPredictionEvaluationResults DoCrossValidation(
this RatingPredictor recommender,
ISplit <IRatings> split,
bool compute_fit = false,
bool show_fold_results = false)
{
var fold_results = new RatingPredictionEvaluationResults[split.NumberOfFolds];
Parallel.For(0, (int)split.NumberOfFolds, i =>
{
try
{
var split_recommender = (RatingPredictor)recommender.Clone(); // to avoid changes in recommender
split_recommender.Ratings = split.Train[i];
if (recommender is ITransductiveRatingPredictor)
{
((ITransductiveRatingPredictor)split_recommender).AdditionalFeedback = split.Test[i];
}
split_recommender.Train();
fold_results[i] = Ratings.Evaluate(split_recommender, split.Test[i]);
if (compute_fit)
{
fold_results[i]["fit"] = (float)split_recommender.ComputeFit();
}
if (show_fold_results)
{
Console.Error.WriteLine("fold {0} {1}", i, fold_results[i]);
}
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw;
}
});
return(new RatingPredictionEvaluationResults(fold_results));
}
/// <summary>Evaluates a rating predictor for RMSE, (N)MAE, and CBD</summary>
/// <remarks>
/// <para>
/// See http://recsyswiki.com/wiki/Root_mean_square_error and http://recsyswiki.com/wiki/Mean_absolute_error
/// </para>
/// <para>
/// For NMAE, see the paper by Goldberg et al.
/// </para>
/// <para>
/// For CBD (capped binomial deviance), see http://www.kaggle.com/c/ChessRatings2/Details/Evaluation
/// </para>
/// <para>
/// If the recommender can take time into account, and the rating dataset provides rating times,
/// this information will be used for making rating predictions.
/// </para>
/// <para>
/// Literature:
/// <list type="bullet">
/// <item><description>
/// Ken Goldberg, Theresa Roeder, Dhruv Gupta, and Chris Perkins:
/// Eigentaste: A Constant Time Collaborative Filtering Algorithm.
/// nformation Retrieval Journal 2001.
/// http://goldberg.berkeley.edu/pubs/eigentaste.pdf
/// </description></item>
/// </list>
/// </para>
/// </remarks>
/// <param name="recommender">rating predictor</param>
/// <param name="test_ratings">test cases</param>
/// <param name="training_ratings">the training examples</param>
/// <returns>a Dictionary containing the evaluation results</returns>
static public RatingPredictionEvaluationResults Evaluate(this IRatingPredictor recommender, IRatings test_ratings, IRatings training_ratings = null)
{
if (recommender == null)
throw new ArgumentNullException("recommender");
if (test_ratings == null)
throw new ArgumentNullException("ratings");
var all_indices = Enumerable.Range(0, test_ratings.Count).ToArray();
var results = new RatingPredictionEvaluationResults(Evaluate(recommender, test_ratings, all_indices));
if (training_ratings != null)
{
var new_user_indices = (from index in all_indices
where test_ratings.Users[index] > training_ratings.MaxUserID || training_ratings.CountByUser[test_ratings.Users[index]] == 0
select index).ToArray();
results.NewUserResults = Evaluate(recommender, test_ratings, new_user_indices);
var new_item_indices = (from index in all_indices
where test_ratings.Items[index] > training_ratings.MaxItemID || training_ratings.CountByItem[test_ratings.Items[index]] == 0 select index).ToArray();
results.NewItemResults = Evaluate(recommender, test_ratings, new_item_indices);
results.NewUserNewItemResults = Evaluate(recommender, test_ratings, Enumerable.Intersect(new_user_indices, new_item_indices).ToArray());
}
return results;
}
/// <summary>Online evaluation for rating prediction</summary>
/// <remarks>
/// Every rating that is tested is added to the training set afterwards.
/// </remarks>
/// <param name="recommender">rating predictor</param>
/// <param name="ratings">Test cases</param>
/// <returns>a Dictionary containing the evaluation results</returns>
static public RatingPredictionEvaluationResults EvaluateOnline(this IRatingPredictor recommender, IRatings ratings)
{
if (recommender == null)
throw new ArgumentNullException("recommender");
if (ratings == null)
throw new ArgumentNullException("ratings");
var incremental_recommender = recommender as IIncrementalRatingPredictor;
if (incremental_recommender == null)
throw new ArgumentException("recommender must be of type IIncrementalRatingPredictor");
double rmse = 0;
double mae = 0;
double cbd = 0;
// iterate in random order
foreach (int index in ratings.RandomIndex)
{
float prediction = recommender.Predict(ratings.Users[index], ratings.Items[index]);
float error = prediction - ratings[index];
rmse += error * error;
mae += Math.Abs(error);
cbd += Eval.Ratings.ComputeCBD(ratings[index], prediction, recommender.MinRating, recommender.MaxRating);
incremental_recommender.AddRatings(new RatingsProxy(ratings, new int[] { index }));
}
mae = mae / ratings.Count;
rmse = Math.Sqrt(rmse / ratings.Count);
cbd = cbd / ratings.Count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float) rmse;
result["MAE"] = (float) mae;
result["NMAE"] = (float) mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float) cbd;
return result;
}
/// <summary>Evaluate an iterative recommender on the folds of a dataset split, display results on STDOUT</summary>
/// <param name="recommender">a rating predictor</param>
/// <param name="split">a rating dataset split</param>
/// <param name="max_iter">the maximum number of iterations</param>
/// <param name="find_iter">the report interval</param>
/// <param name="show_fold_results">if set to true to print per-fold results to STDERR</param>
public static void DoIterativeCrossValidation(
this RatingPredictor recommender,
ISplit<IRatings> split,
int max_iter,
int find_iter = 1,
bool show_fold_results = false)
{
if (!(recommender is IIterativeModel))
throw new ArgumentException("recommender must be of type IIterativeModel");
var split_recommenders = new RatingPredictor[split.NumberOfFolds];
var iterative_recommenders = new IIterativeModel[split.NumberOfFolds];
var fold_results = new RatingPredictionEvaluationResults[split.NumberOfFolds];
// initial training and evaluation
Parallel.For(0, (int) split.NumberOfFolds, i =>
{
try
{
split_recommenders[i] = (RatingPredictor) recommender.Clone(); // to avoid changes in recommender
split_recommenders[i].Ratings = split.Train[i];
if (recommender is ITransductiveRatingPredictor)
((ITransductiveRatingPredictor) split_recommenders[i]).AdditionalFeedback = split.Test[i];
split_recommenders[i].Train();
iterative_recommenders[i] = (IIterativeModel) split_recommenders[i];
fold_results[i] = Ratings.Evaluate(split_recommenders[i], split.Test[i]);
if (show_fold_results)
Console.Error.WriteLine("fold {0} {1} iteration {2}", i, fold_results[i], iterative_recommenders[i].NumIter);
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw e;
}
});
Console.WriteLine("{0} iteration {1}", new RatingPredictionEvaluationResults(fold_results), iterative_recommenders[0].NumIter);
// iterative training and evaluation
for (int it = (int) iterative_recommenders[0].NumIter + 1; it <= max_iter; it++)
{
Parallel.For(0, (int) split.NumberOfFolds, i =>
{
try
{
iterative_recommenders[i].Iterate();
if (it % find_iter == 0)
{
fold_results[i] = Ratings.Evaluate(split_recommenders[i], split.Test[i]);
if (show_fold_results)
Console.Error.WriteLine("fold {0} {1} iteration {2}", i, fold_results[i], it);
}
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw e;
}
});
Console.WriteLine("{0} iteration {1}", new RatingPredictionEvaluationResults(fold_results), it);
}
}
/// <summary>Evaluates a rating predictor for RMSE, (N)MAE, and CBD</summary>
/// <remarks>
/// <para>
/// See http://recsyswiki.com/wiki/Root_mean_square_error and http://recsyswiki.com/wiki/Mean_absolute_error
/// </para>
/// <para>
/// For NMAE, see the paper by Goldberg et al.
/// </para>
/// <para>
/// For CBD (capped binomial deviance), see http://www.kaggle.com/c/ChessRatings2/Details/Evaluation
/// </para>
/// <para>
/// If the recommender can take time into account, and the rating dataset provides rating times,
/// this information will be used for making rating predictions.
/// </para>
/// <para>
/// Literature:
/// <list type="bullet">
/// <item><description>
/// Ken Goldberg, Theresa Roeder, Dhruv Gupta, and Chris Perkins:
/// Eigentaste: A Constant Time Collaborative Filtering Algorithm.
/// nformation Retrieval Journal 2001.
/// http://goldberg.berkeley.edu/pubs/eigentaste.pdf
/// </description></item>
/// </list>
/// </para>
/// </remarks>
/// <param name="recommender">rating predictor</param>
/// <param name="ratings">Test cases</param>
/// <returns>a Dictionary containing the evaluation results</returns>
public static RatingPredictionEvaluationResults Evaluate(this IRatingPredictor recommender, IRatings ratings)
{
double rmse = 0;
double mae = 0;
double cbd = 0;
if (recommender == null)
throw new ArgumentNullException("recommender");
if (ratings == null)
throw new ArgumentNullException("ratings");
if (recommender is ITimeAwareRatingPredictor && ratings is ITimedRatings)
{
var time_aware_recommender = recommender as ITimeAwareRatingPredictor;
var timed_ratings = ratings as ITimedRatings;
for (int index = 0; index < ratings.Count; index++)
{
float prediction = time_aware_recommender.Predict(timed_ratings.Users[index], timed_ratings.Items[index], timed_ratings.Times[index]);
float error = prediction - ratings[index];
rmse += error * error;
mae += Math.Abs(error);
cbd += ComputeCBD(ratings[index], prediction, ratings.MinRating, ratings.MaxRating);
}
}
else
for (int index = 0; index < ratings.Count; index++)
{
float prediction = recommender.Predict(ratings.Users[index], ratings.Items[index]);
float error = prediction - ratings[index];
rmse += error * error;
mae += Math.Abs(error);
cbd += ComputeCBD(ratings[index], prediction, ratings.MinRating, ratings.MaxRating);
}
mae = mae / ratings.Count;
rmse = Math.Sqrt(rmse / ratings.Count);
cbd = cbd / ratings.Count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float) rmse;
result["MAE"] = (float) mae;
result["NMAE"] = (float) mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float) cbd;
return result;
}
/// <summary>Performs user-wise fold-in evaluation, but instead of folding in perform incremental training with the new data</summary>
/// <remarks>
/// </remarks>
/// <returns>the evaluation results</returns>
/// <param name='recommender'>a rating predictor capable of performing a user fold-in</param>
/// <param name='update_data'>the rating data used to represent the users</param>
/// <param name='eval_data'>the evaluation data</param>
static public RatingPredictionEvaluationResults EvaluateFoldInIncrementalTraining(this IncrementalRatingPredictor recommender, IRatings update_data, IRatings eval_data)
{
double rmse = 0;
double mae = 0;
double cbd = 0;
int rating_count = 0;
foreach (int user_id in update_data.AllUsers)
if (eval_data.AllUsers.Contains(user_id))
{
var local_recommender = (IncrementalRatingPredictor) recommender.Clone();
// add ratings and perform incremental training
var user_ratings = new RatingsProxy(update_data, update_data.ByUser[user_id]);
local_recommender.AddRatings(user_ratings);
var items_to_rate = (from index in eval_data.ByUser[user_id] select eval_data.Items[index]).ToArray();
var predicted_ratings = recommender.Recommend(user_id, candidate_items:items_to_rate);
foreach (var pred in predicted_ratings)
{
float prediction = pred.Item2;
float actual_rating = eval_data.Get(user_id, pred.Item1, eval_data.ByUser[user_id]);
float error = prediction - actual_rating;
rmse += error * error;
mae += Math.Abs(error);
cbd += Eval.Ratings.ComputeCBD(actual_rating, prediction, recommender.MinRating, recommender.MaxRating);
rating_count++;
}
// remove ratings again
local_recommender.RemoveRatings(user_ratings);
Console.Error.Write(".");
}
mae = mae / rating_count;
rmse = Math.Sqrt(rmse / rating_count);
cbd = cbd / rating_count;
var result = new RatingPredictionEvaluationResults();
result["RMSE"] = (float) rmse;
result["MAE"] = (float) mae;
result["NMAE"] = (float) mae / (recommender.MaxRating - recommender.MinRating);
result["CBD"] = (float) cbd;
return result;
}
/// <summary>Evaluate an iterative recommender on the folds of a dataset split, display results on STDOUT</summary>
/// <param name="recommender">a rating predictor</param>
/// <param name="split">a rating dataset split</param>
/// <param name="max_iter">the maximum number of iterations</param>
/// <param name="find_iter">the report interval</param>
/// <param name="show_fold_results">if set to true to print per-fold results to STDERR</param>
static public void DoIterativeCrossValidation(
this RatingPredictor recommender,
ISplit <IRatings> split,
uint max_iter,
uint find_iter = 1,
bool show_fold_results = false)
{
if (!(recommender is IIterativeModel))
{
throw new ArgumentException("recommender must be of type IIterativeModel");
}
var split_recommenders = new RatingPredictor[split.NumberOfFolds];
var iterative_recommenders = new IIterativeModel[split.NumberOfFolds];
var fold_results = new RatingPredictionEvaluationResults[split.NumberOfFolds];
// initial training and evaluation
Parallel.For(0, (int)split.NumberOfFolds, i =>
{
try
{
split_recommenders[i] = (RatingPredictor)recommender.Clone(); // to avoid changes in recommender
split_recommenders[i].Ratings = split.Train[i];
if (recommender is ITransductiveRatingPredictor)
{
((ITransductiveRatingPredictor)split_recommenders[i]).AdditionalFeedback = split.Test[i];
}
split_recommenders[i].Train();
iterative_recommenders[i] = (IIterativeModel)split_recommenders[i];
fold_results[i] = Ratings.Evaluate(split_recommenders[i], split.Test[i]);
if (show_fold_results)
{
Console.Error.WriteLine("fold {0} {1} iteration {2}", i, fold_results[i], iterative_recommenders[i].NumIter);
}
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw;
}
});
Console.WriteLine("{0} iteration {1}", new RatingPredictionEvaluationResults(fold_results), iterative_recommenders[0].NumIter);
// iterative training and evaluation
for (int it = (int)iterative_recommenders[0].NumIter + 1; it <= max_iter; it++)
{
Parallel.For(0, (int)split.NumberOfFolds, i =>
{
try
{
iterative_recommenders[i].Iterate();
if (it % find_iter == 0)
{
fold_results[i] = Ratings.Evaluate(split_recommenders[i], split.Test[i]);
if (show_fold_results)
{
Console.Error.WriteLine("fold {0} {1} iteration {2}", i, fold_results[i], it);
}
}
}
catch (Exception e)
{
Console.Error.WriteLine("===> ERROR: " + e.Message + e.StackTrace);
throw;
}
});
Console.WriteLine("{0} iteration {1}", new RatingPredictionEvaluationResults(fold_results), it);
}
}