# fitted(to:validateOn:eventHandler:) Fits a model to a sequence of examples with validation. ``` func fitted(to input: some Sequence, MLShapedArray>>, validateOn validation: some Sequence, MLShapedArray>>, eventHandler: EventHandler? = nil) async throws -> LinearTimeSeriesForecaster.Model ``` ## Parameters `input` A sequence of annotated features. Each feature’s shape should be `[featureSize]` and each annotation’s shape should be `[annotationSize]`. `validation` A sequence of annotated validation features. The feature and annotation shapes should be the same as the input parameter. `eventHandler` An event handler. ## Return Value The fitted model. ## Discussion This method uses a sliding window to chunk the input features and validation features into features of [`inputWindowSize`](/documentation/CreateMLComponents/LinearTimeSeriesForecaster/inputWindowSize) elements and annotations of [`forecastWindowSize`](/documentation/CreateMLComponents/LinearTimeSeriesForecaster/forecastWindowSize) elements. If you want to use a different windowing strategy, use [`fitted(toWindows:validateOn:eventHandler:)`](/documentation/CreateMLComponents/LinearTimeSeriesForecaster/fitted(toWindows:validateOn:eventHandler:)). --- 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)