/// <summary>
/// The counter constructor of re-creating <see cref="MatrixFactorizationPredictionTransformer"/> from the context where
/// the original transform is saved.
/// </summary>
public MatrixFactorizationPredictionTransformer(IHostEnvironment host, ModelLoadContext ctx)
: base(Contracts.CheckRef(host, nameof(host)).Register(nameof(MatrixFactorizationPredictionTransformer)), ctx)
{
// *** Binary format ***
// <base info>
// string: the column name of matrix's column ids.
// string: the column name of matrix's row ids.
MatrixColumnIndexColumnName = ctx.LoadString();
MatrixRowIndexColumnName = ctx.LoadString();
if (!TrainSchema.TryGetColumnIndex(MatrixColumnIndexColumnName, out int xCol))
{
throw Host.ExceptSchemaMismatch(nameof(MatrixColumnIndexColumnName), RecommenderUtils.MatrixColumnIndexKind.Value, MatrixColumnIndexColumnName);
}
MatrixColumnIndexColumnType = TrainSchema.GetColumnType(xCol);
if (!TrainSchema.TryGetColumnIndex(MatrixRowIndexColumnName, out int yCol))
{
throw Host.ExceptSchemaMismatch(nameof(MatrixRowIndexColumnName), RecommenderUtils.MatrixRowIndexKind.Value, MatrixRowIndexColumnName);
}
MatrixRowIndexColumnType = TrainSchema.GetColumnType(yCol);
BindableMapper = ScoreUtils.GetSchemaBindableMapper(Host, Model);
var schema = GetSchema();
var args = new GenericScorer.Arguments {
Suffix = ""
};
Scorer = new GenericScorer(Host, args, new EmptyDataView(Host, TrainSchema), BindableMapper.Bind(Host, schema), schema);
}
/// <summary>
/// Build a transformer based on matrix factorization predictor (model) and the input schema (trainSchema). The created
/// transformer can only transform IDataView objects compatible to the input schema; that is, that IDataView must contain
/// columns specified by <see cref="MatrixColumnIndexColumnName"/>, <see cref="MatrixColumnIndexColumnType"/>, <see cref="MatrixRowIndexColumnName"/>, and <see cref="MatrixRowIndexColumnType"></see>.
/// The output column is "Score" by default but user can append a string to it.
/// </summary>
/// <param name="env">Eviroment object for showing information</param>
/// <param name="model">The model trained by one of the training functions in <see cref="MatrixFactorizationTrainer"/></param>
/// <param name="trainSchema">Targeted schema that containing columns named as xColumnName</param>
/// <param name="matrixColumnIndexColumnName">The name of the column used as role <see cref="RecommenderUtils.MatrixColumnIndexKind"/> in matrix factorization world</param>
/// <param name="matrixRowIndexColumnName">The name of the column used as role <see cref="RecommenderUtils.MatrixRowIndexKind"/> in matrix factorization world</param>
/// <param name="scoreColumnNameSuffix">A string attached to the output column name of this transformer</param>
public MatrixFactorizationPredictionTransformer(IHostEnvironment env, MatrixFactorizationPredictor model, Schema trainSchema,
string matrixColumnIndexColumnName, string matrixRowIndexColumnName, string scoreColumnNameSuffix = "")
: base(Contracts.CheckRef(env, nameof(env)).Register(nameof(MatrixFactorizationPredictionTransformer)), model, trainSchema)
{
Host.CheckNonEmpty(matrixColumnIndexColumnName, nameof(matrixRowIndexColumnName));
Host.CheckNonEmpty(matrixColumnIndexColumnName, nameof(matrixRowIndexColumnName));
MatrixColumnIndexColumnName = matrixColumnIndexColumnName;
MatrixRowIndexColumnName = matrixRowIndexColumnName;
if (!trainSchema.TryGetColumnIndex(MatrixColumnIndexColumnName, out int xCol))
{
throw Host.ExceptSchemaMismatch(nameof(MatrixColumnIndexColumnName), RecommenderUtils.MatrixColumnIndexKind.Value, MatrixColumnIndexColumnName);
}
MatrixColumnIndexColumnType = trainSchema.GetColumnType(xCol);
if (!trainSchema.TryGetColumnIndex(MatrixRowIndexColumnName, out int yCol))
{
throw Host.ExceptSchemaMismatch(nameof(yCol), RecommenderUtils.MatrixRowIndexKind.Value, MatrixRowIndexColumnName);
}
BindableMapper = ScoreUtils.GetSchemaBindableMapper(Host, model);
var schema = GetSchema();
var args = new GenericScorer.Arguments {
Suffix = scoreColumnNameSuffix
};
Scorer = new GenericScorer(Host, args, new EmptyDataView(Host, trainSchema), BindableMapper.Bind(Host, schema), schema);
}
