/// <summary>
/// This function returns a schema for sequence predictor's output. Its output column is always called <see cref="MetadataUtils.Const.ScoreValueKind.PredictedLabel"/>.
/// </summary>
/// <param name="scoreType">Score column's type produced by sequence predictor.</param>
/// <param name="scoreColumnKindValue">A metadata value of score column. It's the value associated with key
/// <see cref="MetadataUtils.Kinds.ScoreColumnKind"/>.</param>
/// <param name="keyNames">Sequence predictor usually generates integer outputs. This field tells the tags of all possible output values.
/// For example, output integer 0 cound be mapped to "Sell" and 0 to "Buy" when predicting stock trend.</param>
/// <returns><see cref="DataViewSchema"/> of sequence predictor's output.</returns>
public static DataViewSchema CreateSequencePredictionSchema(DataViewType scoreType, string scoreColumnKindValue, VBuffer <ReadOnlyMemory <char> > keyNames = default)
{
Contracts.CheckValue(scoreType, nameof(scoreType));
Contracts.CheckValue(scoreColumnKindValue, nameof(scoreColumnKindValue));
var metadataBuilder = new MetadataBuilder();
// Add metadata columns including their getters. We starts with key names of predicted keys if they exist.
if (keyNames.Length > 0)
{
metadataBuilder.AddKeyValues(keyNames.Length, TextDataViewType.Instance,
(ref VBuffer <ReadOnlyMemory <char> > value) => value = keyNames);
}
metadataBuilder.Add(MetadataUtils.Kinds.ScoreColumnKind, TextDataViewType.Instance,
(ref ReadOnlyMemory <char> value) => value = scoreColumnKindValue.AsMemory());
metadataBuilder.Add(MetadataUtils.Kinds.ScoreValueKind, TextDataViewType.Instance,
(ref ReadOnlyMemory <char> value) => value = MetadataUtils.Const.ScoreValueKind.PredictedLabel.AsMemory());
// Build a schema consisting of a single column.
var schemaBuilder = new SchemaBuilder();
schemaBuilder.AddColumn(MetadataUtils.Const.ScoreValueKind.PredictedLabel, scoreType, metadataBuilder.GetMetadata());
return(schemaBuilder.GetSchema());
}
public DataView(IHostEnvironment env, ArrayDataViewBuilder builder, int rowCount)
{
Contracts.AssertValue(env, "env");
_host = env.Register("ArrayDataView");
_host.AssertValue(builder);
_host.Assert(rowCount >= 0);
_host.Assert(builder._names.Count == builder._columns.Count);
_columns = builder._columns.ToArray();
var schemaBuilder = new SchemaBuilder();
for (int i = 0; i < _columns.Length; i++)
{
var meta = new MetadataBuilder();
if (builder._getSlotNames.TryGetValue(builder._names[i], out var slotNamesGetter))
{
meta.AddSlotNames(_columns[i].Type.GetVectorSize(), slotNamesGetter);
}
if (builder._getKeyValues.TryGetValue(builder._names[i], out var keyValueGetter))
{
meta.AddKeyValues(_columns[i].Type.GetKeyCount(), TextType.Instance, keyValueGetter);
}
schemaBuilder.AddColumn(builder._names[i], _columns[i].Type, meta.GetMetadata());
}
_schema = schemaBuilder.GetSchema();
_rowCount = rowCount;
}