# ColumnConcatenator A transformer that concatenates every numerical column in a dataframe into to a shaped array for each row. ``` struct ColumnConcatenator where Scalar : MLShapedArrayScalar, Scalar : BinaryFloatingPoint ``` ## Overview The resulting concatenated column contains `MLShapedArray` elements. For example ``` ┏━━━┳━━━━━━━━━━┳━━━━━━━━━┳━━━━━━━┳━━━━━━━┳━━━━━━━┳━━━━━━━┓ ┃ ┃ label ┃ price ┃ rooms ┃ A ┃ B ┃ C ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┡━━━╇━━━━━━━━━━╇━━━━━━━━━╇━━━━━━━╇━━━━━━━╇━━━━━━━╇━━━━━━━┩ │ 0 │ good │ 850,000 │ 4 │ 1 │ 0 │ 0 │ │ 1 │ bad │ 700,000 │ 3 │ 0 │ 1 │ 0 │ │ 2 │ bad │ 650,000 │ 3 │ 0 │ 0 │ 1 │ │ 3 │ good │ 600,000 │ 2 │ 0 │ 1 │ 0 │ └───┴──────────┴─────────┴───────┴───────┴───────┴───────┘ ``` would be concatenated as: ``` ┏━━━┳━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━┓ ┃ ┃ label ┃ features ┃ ┃ ┃ ┃ > ┃ ┡━━━╇━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━┩ │ 0 │ good │ [850,000, 4, 1, 0, 0] │ │ 1 │ bad │ [700,000, 3, 0, 1, 0] │ │ 2 │ bad │ [650,000, 3, 0, 0, 1] │ │ 3 │ good │ [600,000, 2, 0, 1, 0] │ └───┴──────────┴────────────────────────┘ ``` Non-numerical columns are left in the data frame unchanged. Supported numeric types are `Int`, `UInt8`, `Float`, and `Double`. Arrays and shaped arrays of those types as supported, but every array in a given column must have the same shape and shaped arrays across columns must have the same shape except for the last dimension. ## Topics ### Creating the concatenator [`init(columnSelection: ColumnSelection, concatenatedColumnName: String)`](/documentation/CreateMLComponents/ColumnConcatenator/init(columnSelection:concatenatedColumnName:)) Creates a concatenator that concatenates numeric columns into a new column of ML shaped array. ### Getting the properties [`var columnSelection: ColumnSelection`](/documentation/CreateMLComponents/ColumnConcatenator/columnSelection) The selection of columns to concatenate. [`var concatenatedColumnName: String`](/documentation/CreateMLComponents/ColumnConcatenator/concatenatedColumnName) The name of the concatenated column containing the shaped arrays. ### Applying [`func applied(to: DataFrame, eventHandler: EventHandler?) throws -> DataFrame`](/documentation/CreateMLComponents/ColumnConcatenator/applied(to:eventHandler:)) Combines every numerical column in a data frame into to a shaped array for each row. ## Relationships ### Conforms To [`Transformer`](/documentation/CreateMLComponents/Transformer) [`Escapable`](/documentation/Swift/Escapable) [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) [`Copyable`](/documentation/Swift/Copyable) [`TabularTransformer`](/documentation/CreateMLComponents/TabularTransformer) --- 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)