# AnnotatedFeatureProvider An adaptor that converts a regular estimator to a tabular estimator by selecting features and annotations from columns. ``` struct AnnotatedFeatureProvider where Base : SupervisedEstimator, Base.Transformer.Input == UnwrappedInput? ``` ## Overview Tabular estimators use multiple features columns as input. When there is a single column of features, you may use a non-tabular estimator. Do this by combining multiple columns with a `ColumnConcatenator` transformer. Once there is a single column of features, use `AnnotatedFeatureProvider` to specify which column contains the features, which column contains the annotations, and which column should hold the results. When using `AnnotatedFeatureProvider`, make sure to handle missing values before using a non-tabular estimator that takes non-optional values. This example includes an `OptionalUnwrapper` transformer. ``` let concatenation = ColumnConcatenator( columnSelection: .include(columnNames: ["type", "region"]), concatenatedColumnName: "features" ) let regression = AnnotatedFeatureProvider( OptionalUnwrapper>().appending(LinearRegressor()), annotationsColumnName: "price", featuresColumnName: "features", resultsColumnName: "result" ) let task = concatenation.appending(regression) ``` ## Topics ### Creating the provider [`init(Base, annotationsColumnName: String, featuresColumnName: String, resultsColumnName: String)`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/init(_:annotationsColumnName:featuresColumnName:resultsColumnName:)) Creates an adaptor that converts a regular estimator to a tabular estimator. ### Getting the properties [`var annotationColumnID: ColumnID.Annotation>`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/annotationColumnID) The annotation column identifier. [`typealias Annotation`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/Annotation) The annotation type. [`var base: Base`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/base) The base estimator. [`var featuresColumnName: String`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/featuresColumnName) The features column name. [`var resultsColumnName: String`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/resultsColumnName) The results column name. ### Encoding and decoding [`func encode(AnnotatedFeatureProvider.Transformer, to: inout any EstimatorEncoder) throws`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/encode(_:to:)) Encodes a fitted transformer. [`func decode(from: inout any EstimatorDecoder) throws -> AnnotatedFeatureProvider.Transformer`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/decode(from:)) Decodes a previously fitted transformer. ### Fitting [`func fitted(to: DataFrame, validateOn: DataFrame?, eventHandler: EventHandler?) async throws -> ColumnSelectorTransformer`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/fitted(to:validateOn:eventHandler:)) Fits a transformer to a data frame [`typealias Transformer`](/documentation/CreateMLComponents/AnnotatedFeatureProvider/Transformer) The transformer type created by this estimator. ### Default Implementations [UpdatableSupervisedTabularEstimator Implementations](/documentation/CreateMLComponents/AnnotatedFeatureProvider/UpdatableSupervisedTabularEstimator-Implementations) ## Relationships ### Conforms To [`Escapable`](/documentation/Swift/Escapable) [`Copyable`](/documentation/Swift/Copyable) [`SupervisedTabularEstimator`](/documentation/CreateMLComponents/SupervisedTabularEstimator) [`UpdatableSupervisedTabularEstimator`](/documentation/CreateMLComponents/UpdatableSupervisedTabularEstimator) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)