/// <summary>
/// Returns the <see cref="SchemaShape"/> of the schema which will be produced by the transformer.
/// Used for schema propagation and verification in a pipeline.
/// </summary>
public SchemaShape GetOutputSchema(SchemaShape inputSchema)
{
_host.CheckValue(inputSchema, nameof(inputSchema));
var result = inputSchema.ToDictionary(x => x.Name);
foreach (var colPair in _columns)
{
if (!inputSchema.TryFindColumn(colPair.InputColumnName, out var col))
{
throw _host.ExceptSchemaMismatch(nameof(inputSchema), "input", colPair.InputColumnName);
}
if (!CountFeatureSelectionUtils.IsValidColumnType(col.ItemType))
{
throw _host.ExceptUserArg(nameof(inputSchema), "Column '{0}' does not have compatible type. Expected types are float, double or string.", colPair.InputColumnName);
}
var metadata = new List <SchemaShape.Column>();
if (col.Annotations.TryFindColumn(AnnotationUtils.Kinds.SlotNames, out var slotMeta))
{
metadata.Add(slotMeta);
}
if (col.Annotations.TryFindColumn(AnnotationUtils.Kinds.CategoricalSlotRanges, out var categoricalSlotMeta))
{
metadata.Add(categoricalSlotMeta);
}
if (col.IsNormalized() && col.Annotations.TryFindColumn(AnnotationUtils.Kinds.IsNormalized, out var isNormalizedAnnotation))
{
metadata.Add(isNormalizedAnnotation);
}
result[colPair.Name] = new SchemaShape.Column(colPair.Name, col.Kind, col.ItemType, false, new SchemaShape(metadata.ToArray()));
}
return(new SchemaShape(result.Values));
}
