# fitted(toPreprocessed:eventHandler:) Fits a transformer to a sequence of preprocessed features. ``` func fitted(toPreprocessed preprocessed: S, eventHandler: EventHandler? = nil) async throws -> PreprocessingEstimator.Transformer where S : Sequence, Preprocessor.Output == S.Element, S.Element == Estimator.Transformer.Input ``` ## Parameters `preprocessed` A sequence of preprocessed features. `eventHandler` An event handler. ## Return Value The fitted transformer. --- 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)