# stratifiedSplit(on:by:randomSeed:) Generates two data frames by randomly splitting the rows of a column, which you select by column identifier, into strata. ``` func stratifiedSplit(on columnID: ColumnID, by proportion: Double, randomSeed: Int? = nil) -> (DataFrame, DataFrame) where T : Hashable ``` ## Parameters `columnID` A column identifier. `proportion` A proportion in the range `[0.0, 1.0]`. `randomSeed` A seed number for a random-number generator. ## Return Value A tuple of two data frames. --- 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)