# subscript(_:) Returns a `MLDataColumn` containing only the elements for which the corresponding mask has a nonzero or non-default value. ``` subscript(mask: MLUntypedColumn) -> MLDataColumn { get } ``` ## Parameters `mask` a MLUntypedColumn with the same element count as this MLUntypedColumn. ## Return Value A MLUntypedColumn containing the subsequence of this MLUntypedColumn’s elements indicated by the mask MLUntypedColumn. --- 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)