# OneHotEncoder An estimator that encodes categorical values to an integer array. ``` struct OneHotEncoder where Category : Comparable, Category : Decodable, Category : Encodable, Category : Hashable ``` ## Overview The encoded array has an element count equal to the number of categories to encode. The encoded array for a given category has repeating zero values except at one index where the value is 1. ## Topics ### Creating the estimator [`init()`](/documentation/CreateMLComponents/OneHotEncoder/init()) Creates a one-hot encoding estimator. ### Fitting [`func fitted(to: S, eventHandler: EventHandler?) throws -> OneHotEncoder.Transformer`](/documentation/CreateMLComponents/OneHotEncoder/fitted(to:eventHandler:)) Fits a one-hot encoder to a sequence of categories. ### Default Implementations [Estimator Implementations](/documentation/CreateMLComponents/OneHotEncoder/Estimator-Implementations) [UpdatableEstimator Implementations](/documentation/CreateMLComponents/OneHotEncoder/UpdatableEstimator-Implementations) ## Relationships ### Conforms To [`Estimator`](/documentation/CreateMLComponents/Estimator) [`UpdatableEstimator`](/documentation/CreateMLComponents/UpdatableEstimator) [`Escapable`](/documentation/Swift/Escapable) [`Copyable`](/documentation/Swift/Copyable) [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- 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)