///
public override float Predict(int user_id, int item_id)
{
double result = global_bias;
if (user_id < user_bias.Length)
{
result += user_bias[user_id];
}
if (item_id < item_bias.Length)
{
result += item_bias[item_id];
}
if (user_id < user_attributes.NumberOfRows)
{
IList <int> attribute_list = user_attributes.GetEntriesByRow(user_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_demo[attribute_id];
}
result += sum / second_norm_denominator;
}
}
for (int d = 0; d < additional_user_attributes.Count; d++)
{
if (user_id < additional_user_attributes[d].NumberOfRows)
{
IList <int> attribute_list = additional_user_attributes[d].GetEntriesByRow(user_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_demo[d][attribute_id];
}
result += sum / second_norm_denominator;
}
}
}
if (item_id < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_metadata[attribute_id];
}
result += sum / second_norm_denominator;
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (item_id < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_metadata[g][attribute_id];
}
result += sum / second_norm_denominator;
}
}
}
if (user_id < UserAttributes.NumberOfRows && item_id < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(item_id);
double item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(user_id);
float user_norm_denominator = user_attribute_list.Count;
float demo_spec = 0;
float sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[0][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(user_id);
user_norm_denominator = user_attribute_list.Count;
sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[d + 1][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
}
result += demo_spec / item_norm_denominator;
}
if (user_id <= MaxUserID && item_id <= MaxItemID)
{
result += DataType.MatrixExtensions.RowScalarProduct(user_factors, user_id, item_factors, item_id);
}
if (result > MaxRating)
{
return(MaxRating);
}
if (result < MinRating)
{
return(MinRating);
}
return((float)result);
}
///
protected override void Iterate(IList <int> rating_indices, bool update_user, bool update_item)
{
float reg = Regularization; // to limit property accesses
foreach (int index in rating_indices)
{
int u = ratings.Users[index];
int i = ratings.Items[index];
double prediction = global_bias + user_bias[u] + item_bias[i];
if (u < user_attributes.NumberOfRows)
{
IList <int> attribute_list = user_attributes.GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_demo[attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
for (int d = 0; d < additional_user_attributes.Count; d++)
{
if (u < additional_user_attributes[d].NumberOfRows)
{
IList <int> attribute_list = additional_user_attributes[d].GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_demo[d][attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
}
if (i < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_metadata[attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (i < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_metadata[g][attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
}
if (u < UserAttributes.NumberOfRows && i < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(i);
double item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(u);
float user_norm_denominator = user_attribute_list.Count;
float demo_spec = 0;
float sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[0][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
user_norm_denominator = user_attribute_list.Count;
sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[d + 1][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
}
prediction += demo_spec / item_norm_denominator;
}
prediction += DataType.MatrixExtensions.RowScalarProduct(user_factors, u, item_factors, i);
double err = ratings[index] - prediction;
float user_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByUser[u])) : reg;
float item_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByItem[i])) : reg;
// adjust biases
if (update_user)
{
user_bias[u] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * user_reg_weight * user_bias[u]);
}
if (update_item)
{
item_bias[i] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * item_reg_weight * item_bias[i]);
}
// adjust user attributes
if (u < user_attributes.NumberOfRows)
{
IList <int> attribute_list = user_attributes.GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
double second_norm_denominator = attribute_list.Count;
double second_norm_error = err / second_norm_denominator;
foreach (int attribute_id in attribute_list)
{
main_demo[attribute_id] += BiasLearnRate * current_learnrate * ((float)second_norm_error - BiasReg * reg * main_demo[attribute_id]);
}
}
}
for (int d = 0; d < additional_user_attributes.Count; d++)
{
if (u < additional_user_attributes[d].NumberOfRows)
{
IList <int> attribute_list = additional_user_attributes[d].GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
double second_norm_denominator = attribute_list.Count;
double second_norm_error = err / second_norm_denominator;
foreach (int attribute_id in attribute_list)
{
second_demo[d][attribute_id] += BiasLearnRate * current_learnrate * ((float)second_norm_error - BiasReg * reg * second_demo[d][attribute_id]);
}
}
}
}
// adjust item attributes
if (i < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
main_metadata[attribute_id] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * Regularization * main_metadata[attribute_id]);
}
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (i < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
second_metadata[g][attribute_id] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * Regularization * second_metadata[g][attribute_id]);
}
}
}
}
// adjust demo specific attributes
if (u < UserAttributes.NumberOfRows && i < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(i);
float item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(u);
float user_norm = 1 / user_attribute_list.Count;
float norm_error = (float)err / item_norm_denominator;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
h[0][u_att, i_att] += BiasLearnRate * current_learnrate * (norm_error * user_norm - BiasReg * reg * h[0][u_att, i_att]);
}
}
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
user_norm = 1 / user_attribute_list.Count;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
h[d + 1][u_att, i_att] += BiasLearnRate * current_learnrate * (norm_error * user_norm - BiasReg * reg * h[d + 1][u_att, i_att]);;
}
}
}
}
// adjust latent factors
for (int f = 0; f < NumFactors; f++)
{
double u_f = user_factors[u, f];
double i_f = item_factors[i, f];
if (update_user)
{
double delta_u = err * i_f - user_reg_weight * u_f;
user_factors.Inc(u, f, current_learnrate * delta_u);
}
if (update_item)
{
double delta_i = err * u_f - item_reg_weight * i_f;
item_factors.Inc(i, f, current_learnrate * delta_i);
}
}
}
UpdateLearnRate();
}
/// <summary>
/// Iterate once over rating data and adjust corresponding factors (stochastic gradient descent)
/// </summary>
/// <param name='rating_indices'>
/// a list of indices pointing to the ratings to iterate over
/// </param>
/// <param name='update_user'>
/// true if user factors to be updated
/// </param>
/// <param name='update_item'>
/// true if item factors to be updated
/// </param>
protected override void Iterate(IList <int> rating_indices, bool update_user, bool update_item)
{
user_factors = null; // delete old user factors
float reg = Regularization; // to limit property accesses
foreach (int index in rating_indices)
{
int u = ratings.Users[index];
int i = ratings.Items[index];
float prediction = global_bias + user_bias[u] + item_bias[i];
var p_plus_y_sum_vector = y.SumOfRows(items_rated_by_user[u]);
double norm_denominator = Math.Sqrt(items_rated_by_user[u].Length);
for (int f = 0; f < p_plus_y_sum_vector.Count; f++)
{
p_plus_y_sum_vector[f] = (float)(p_plus_y_sum_vector[f] / norm_denominator + p[u, f]);
}
prediction += DataType.MatrixExtensions.RowScalarProduct(item_factors, i, p_plus_y_sum_vector);
// MANZATO FIX
if (u < UserAttributes.NumberOfRows)
{
IList <int> attribute_list = UserAttributes.GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
float sum = 0;
float second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_demo[attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
// MANZATO FIX
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
if (u < AdditionalUserAttributes[d].NumberOfRows)
{
IList <int> attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
float sum = 0;
float second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_demo[d][attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
}
// MANZATO ADD
if (i < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
float sum = 0;
float second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_metadata[attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (i < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
float sum = 0;
float second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_metadata[g][attribute_id];
}
prediction += sum / second_norm_denominator;
}
}
}
// MANZATO FIX
if (u < UserAttributes.NumberOfRows && i < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(i);
float item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(u);
float user_norm_denominator = user_attribute_list.Count;
float demo_spec = 0;
float sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[0][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
user_norm_denominator = user_attribute_list.Count;
sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[d + 1][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
}
prediction += demo_spec / item_norm_denominator;
}
float err = ratings[index] - prediction;
float user_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByUser[u])) : reg;
float item_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByItem[i])) : reg;
// adjust biases
if (update_user)
{
user_bias[u] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * user_reg_weight * user_bias[u]);
}
if (update_item)
{
item_bias[i] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * item_reg_weight * item_bias[i]);
}
// adjust factors || DITO extension
double normalized_error = err / norm_denominator;
for (int f = 0; f < NumFactors; f++)
{
float i_f = item_factors[i, f];
// if necessary, compute and apply updates
if (update_user)
{
double delta_u = err * i_f - user_reg_weight * p[u, f];
p.Inc(u, f, current_learnrate * delta_u);
}
if (update_item)
{
double delta_i = err * p_plus_y_sum_vector[f] - item_reg_weight * i_f;
item_factors.Inc(i, f, current_learnrate * delta_i);
double common_update = normalized_error * i_f;
foreach (int other_item_id in items_rated_by_user[u])
{
double delta_oi = common_update - y_reg[other_item_id] * y[other_item_id, f];
y.Inc(other_item_id, f, current_learnrate * delta_oi);
}
}
}
// adjust demo global attributes
if (u < UserAttributes.NumberOfRows)
{
IList <int> attribute_list = UserAttributes.GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
main_demo[attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * main_demo[attribute_id]);
}
}
}
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
if (u < AdditionalUserAttributes[d].NumberOfRows)
{
IList <int> attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
second_demo[d][attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * second_demo[d][attribute_id]);
}
}
}
}
// adjust metadata global attributes
// adjust item attributes
if (i < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
main_metadata[attribute_id] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * Regularization * main_metadata[attribute_id]);
}
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (i < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
second_metadata[g][attribute_id] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * Regularization * second_metadata[g][attribute_id]);
}
}
}
}
// adjust demo specific attributes
if (u < UserAttributes.NumberOfRows && i < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(i);
float item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(u);
float user_norm = 1 / user_attribute_list.Count;
float norm_error = err / item_norm_denominator;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
h[0][u_att, i_att] += current_learnrate * (norm_error * user_norm - Regularization * h[0][u_att, i_att]);
}
}
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
user_norm = 1 / user_attribute_list.Count;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
h[d + 1][u_att, i_att] += current_learnrate * (norm_error * user_norm - Regularization * h[d + 1][u_att, i_att]);;
}
}
}
}
}
UpdateLearnRate();
}
///
protected override float Predict(int user_id, int item_id, bool bound)
{
double result = global_bias;
if (user_id < user_bias.Length)
{
result += user_bias[user_id];
}
if (item_id < item_bias.Length)
{
result += item_bias[item_id];
}
if (user_id < UserAttributes.NumberOfRows)
{
IList <int> attribute_list = UserAttributes.GetEntriesByRow(user_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_demo[attribute_id];
}
result += sum / second_norm_denominator;
}
}
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
if (user_id < AdditionalUserAttributes[d].NumberOfRows)
{
IList <int> attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(user_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_demo[d][attribute_id];
}
result += sum / second_norm_denominator;
}
}
}
if (item_id < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_metadata[attribute_id];
}
result += sum / second_norm_denominator;
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (item_id < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_metadata[g][attribute_id];
}
result += sum / second_norm_denominator;
}
}
}
if (bound)
{
if (result > MaxRating)
{
return(MaxRating);
}
if (result < MinRating)
{
return(MinRating);
}
}
return((float)result);
}
///
protected override void Iterate(IList <int> rating_indices, bool update_user, bool update_item)
{
float reg = Regularization; // to limit property accesses
foreach (int index in rating_indices)
{
int u = ratings.Users[index];
int i = ratings.Items[index];
float prediction = Predict(u, i, false);
float err = ratings[index] - prediction;
float user_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByUser[u])) : reg;
float item_reg_weight = FrequencyRegularization ? (float)(reg / Math.Sqrt(ratings.CountByItem[i])) : reg;
// adjust biases
if (update_user)
{
user_bias[u] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * user_reg_weight * user_bias[u]);
}
if (update_item)
{
item_bias[i] += BiasLearnRate * current_learnrate * ((float)err - BiasReg * item_reg_weight * item_bias[i]);
}
// adjust user attributes
if (u < UserAttributes.NumberOfRows)
{
IList <int> attribute_list = UserAttributes.GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
main_demo[attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * main_demo[attribute_id]);
}
}
}
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
if (u < AdditionalUserAttributes[d].NumberOfRows)
{
IList <int> attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(u);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
second_demo[d][attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * second_demo[d][attribute_id]);
}
}
}
}
// adjust item attributes
if (i < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
main_metadata[attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * main_metadata[attribute_id]);
}
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (i < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(i);
if (attribute_list.Count > 0)
{
foreach (int attribute_id in attribute_list)
{
second_metadata[g][attribute_id] += BiasLearnRate * current_learnrate * (err - BiasReg * Regularization * second_metadata[g][attribute_id]);
}
}
}
}
}
UpdateLearnRate();
}
///
protected override float Predict(int user_id, int item_id, bool bound)
{
double result = base.Predict(user_id, item_id, false);
if (user_id < UserAttributes.NumberOfRows && item_id < ItemAttributes.NumberOfRows)
{
IList <int> item_attribute_list = ItemAttributes.GetEntriesByRow(item_id);
double item_norm_denominator = item_attribute_list.Count;
IList <int> user_attribute_list = UserAttributes.GetEntriesByRow(user_id);
float user_norm_denominator = user_attribute_list.Count;
float demo_spec = 0;
float sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[0][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
for (int d = 0; d < AdditionalUserAttributes.Count; d++)
{
user_attribute_list = AdditionalUserAttributes[d].GetEntriesByRow(user_id);
user_norm_denominator = user_attribute_list.Count;
sum = 0;
foreach (int u_att in user_attribute_list)
{
foreach (int i_att in item_attribute_list)
{
sum += h[d + 1][u_att, i_att];
}
}
demo_spec += sum / user_norm_denominator;
}
result += demo_spec / item_norm_denominator;
}
if (item_id < ItemAttributes.NumberOfRows)
{
IList <int> attribute_list = ItemAttributes.GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += main_metadata[attribute_id];
}
result += sum / second_norm_denominator;
}
}
for (int g = 0; g < AdditionalItemAttributes.Count; g++)
{
if (item_id < AdditionalItemAttributes[g].NumberOfRows)
{
IList <int> attribute_list = AdditionalItemAttributes[g].GetEntriesByRow(item_id);
if (attribute_list.Count > 0)
{
double sum = 0;
double second_norm_denominator = attribute_list.Count;
foreach (int attribute_id in attribute_list)
{
sum += second_metadata[g][attribute_id];
}
result += sum / second_norm_denominator;
}
}
}
if (bound)
{
if (result > MaxRating)
{
return(MaxRating);
}
if (result < MinRating)
{
return(MinRating);
}
}
return((float)result);
}
