/// <summary>
/// Given a view and a bunch of column names, create the RoleMappedData object. Any or all of the column
/// names may be null or whitespace, in which case they are ignored. Any columns that are specified but not
/// valid columns of the schema are also ignored.
/// </summary>
public static RoleMappedData CreateExamplesOpt(IDataView view, string label, string feature,
string group = null, string weight = null, string name = null,
IEnumerable <KeyValuePair <ColumnRole, string> > custom = null)
{
Contracts.CheckValueOrNull(label);
Contracts.CheckValueOrNull(feature);
Contracts.CheckValueOrNull(group);
Contracts.CheckValueOrNull(weight);
Contracts.CheckValueOrNull(name);
Contracts.CheckValueOrNull(custom);
var list = new List <KeyValuePair <ColumnRole, string> >();
if (!string.IsNullOrWhiteSpace(label))
{
list.Add(ColumnRole.Label.Bind(label));
}
if (!string.IsNullOrWhiteSpace(feature))
{
list.Add(ColumnRole.Feature.Bind(feature));
}
if (!string.IsNullOrWhiteSpace(group))
{
list.Add(ColumnRole.Group.Bind(group));
}
if (!string.IsNullOrWhiteSpace(weight))
{
list.Add(ColumnRole.Weight.Bind(weight));
}
if (!string.IsNullOrWhiteSpace(name))
{
list.Add(ColumnRole.Name.Bind(name));
}
if (custom != null)
{
list.AddRange(custom);
}
return(RoleMappedData.CreateOpt(view, list));
}
private FoldResult RunFold(int fold)
{
var host = GetHost();
host.Assert(0 <= fold && fold <= _numFolds);
// REVIEW: Make channels buffered in multi-threaded environments.
using (var ch = host.Start($"Fold {fold}"))
{
ch.Trace("Constructing trainer");
ITrainer trainer = _trainer.CreateInstance(host);
// Train pipe.
var trainFilter = new RangeFilter.Arguments();
trainFilter.Column = _splitColumn;
trainFilter.Min = (Double)fold / _numFolds;
trainFilter.Max = (Double)(fold + 1) / _numFolds;
trainFilter.Complement = true;
IDataView trainPipe = new RangeFilter(host, trainFilter, _inputDataView);
trainPipe = new OpaqueDataView(trainPipe);
var trainData = _createExamples(host, ch, trainPipe, trainer);
// Test pipe.
var testFilter = new RangeFilter.Arguments();
testFilter.Column = trainFilter.Column;
testFilter.Min = trainFilter.Min;
testFilter.Max = trainFilter.Max;
ch.Assert(!testFilter.Complement);
IDataView testPipe = new RangeFilter(host, testFilter, _inputDataView);
testPipe = new OpaqueDataView(testPipe);
var testData = _applyTransformsToTestData(host, ch, testPipe, trainData, trainPipe);
// Validation pipe and examples.
RoleMappedData validData = null;
if (_getValidationDataView != null)
{
ch.Assert(_applyTransformsToValidationData != null);
if (!TrainUtils.CanUseValidationData(trainer))
{
ch.Warning("Trainer does not accept validation dataset.");
}
else
{
ch.Trace("Constructing the validation pipeline");
IDataView validLoader = _getValidationDataView();
var validPipe = ApplyTransformUtils.ApplyAllTransformsToData(host, _inputDataView, validLoader);
validPipe = new OpaqueDataView(validPipe);
validData = _applyTransformsToValidationData(host, ch, validPipe, trainData, trainPipe);
}
}
// Train.
var predictor = TrainUtils.Train(host, ch, trainData, trainer, _trainer.Kind, validData,
_calibrator, _maxCalibrationExamples, _cacheData, _inputPredictor);
// Score.
ch.Trace("Scoring and evaluating");
var bindable = ScoreUtils.GetSchemaBindableMapper(host, predictor, _scorer);
ch.AssertValue(bindable);
var mapper = bindable.Bind(host, testData.Schema);
var scorerComp = _scorer.IsGood() ? _scorer : ScoreUtils.GetScorerComponent(mapper);
IDataScorerTransform scorePipe = scorerComp.CreateInstance(host, testData.Data, mapper, trainData.Schema);
// Save per-fold model.
string modelFileName = ConstructPerFoldName(_outputModelFile, fold);
if (modelFileName != null && _loader != null)
{
using (var file = host.CreateOutputFile(modelFileName))
{
var rmd = RoleMappedData.Create(
CompositeDataLoader.ApplyTransform(host, _loader, null, null,
(e, newSource) => ApplyTransformUtils.ApplyAllTransformsToData(e, trainData.Data, newSource)),
trainData.Schema.GetColumnRoleNames());
TrainUtils.SaveModel(host, ch, file, predictor, rmd, _cmd);
}
}
// Evaluate.
var evalComp = _evaluator;
if (!evalComp.IsGood())
{
evalComp = EvaluateUtils.GetEvaluatorType(ch, scorePipe.Schema);
}
var eval = evalComp.CreateInstance(host);
// Note that this doesn't require the provided columns to exist (because of "Opt").
// We don't normally expect the scorer to drop columns, but if it does, we should not require
// all the columns in the test pipeline to still be present.
var dataEval = RoleMappedData.CreateOpt(scorePipe, testData.Schema.GetColumnRoleNames());
var dict = eval.Evaluate(dataEval);
IDataView perInstance = null;
if (_savePerInstance)
{
var perInst = eval.GetPerInstanceMetrics(dataEval);
var perInstData = RoleMappedData.CreateOpt(perInst, dataEval.Schema.GetColumnRoleNames());
perInstance = eval.GetPerInstanceDataViewToSave(perInstData);
}
ch.Done();
return(new FoldResult(dict, dataEval.Schema.Schema, perInstance, trainData.Schema));
}
}