# DataFrame.Slice A set of a data frame’s rows you create by using a method from a data frame instance or another data frame slice. ``` @dynamicMemberLookup struct Slice ``` ## Overview A slice is an arbitrary set of rows from a data frame. For example, a slice might contain rows 0–3, 5–9, and 101 from its underlying data frame. ## Topics ### Inspecting a Slice [`var shape: (rows: Int, columns: Int)`](/documentation/TabularData/DataFrame/Slice/shape) The number of rows and columns in the slice. [`var columns: [AnyColumnSlice]`](/documentation/TabularData/DataFrame/Slice/columns) The entire slice as a collection of columns. [`var rows: DataFrame.Rows`](/documentation/TabularData/DataFrame/Slice/rows) The entire slice as a collection of rows. [`var base: DataFrame`](/documentation/TabularData/DataFrame/Slice/base) The underlying data frame. ### Accessing Rows ### Creating a Slice by Selecting a Column [`subscript(ColumnID) -> DiscontiguousColumnSlice`](/documentation/TabularData/DataFrame/Slice/subscript(_:)-32h9z) Returns a column you select by its column identifier. [`subscript(column _: Int, T.Type) -> DiscontiguousColumnSlice`](/documentation/TabularData/DataFrame/Slice/subscript(column:_:)) Returns a column you select by its index. [`subscript(String, T.Type) -> DiscontiguousColumnSlice`](/documentation/TabularData/DataFrame/Slice/subscript(_:_:)) Returns a column you select by its name and type. [`subscript(String) -> AnyColumnSlice`](/documentation/TabularData/DataFrame/Slice/subscript(_:)-18kdy) Returns a column you select by its name. [`subscript(dynamicMember _: String) -> AnyColumnSlice`](/documentation/TabularData/DataFrame/Slice/subscript(dynamicMember:)) Returns a column you select by its name to support dynamic-member lookup. ### Creating a Slice by Selecting Multiple Columns [`subscript(S) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/subscript(_:)-5y42o) Generates a data frame slice that includes the columns in a sequence of column names. [`func selecting(columnNames: S) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/selecting(columnNames:)-9l8oe) Generates a data frame slice that includes the columns you select with a sequence of names. [`func selecting(columnNames: String...) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/selecting(columnNames:)-48kji) Generates a data frame slice that includes the columns you select with a list of names. ### Creating a Slice by Selecting Rows [`func prefix(Int) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/prefix(_:)) Returns a new slice that contains the initial elements of the original slice. [`func prefix(upTo: Int) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/prefix(upTo:)) Returns a new slice that contains the initial elements of the original slice up to, but not including, the element at a position. [`func prefix(through: Int) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/prefix(through:)) Returns a new slice that contains the initial elements of the original slice up to and including the element at a position. [`func suffix(Int) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/suffix(_:)) Returns a new slice that contains the final elements of the original slice. [`func suffix(from: Int) -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/suffix(from:)) Returns a new slice that contains the final elements of the original slice beginning with the element at a position. ### Creating a Slice by Filtering Rows [`func filter(on: ColumnID, (T?) throws -> Bool) rethrows -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/filter(on:_:)) Returns a selection of rows that satisfy a predicate in the columns you select by column identifier. [`func filter(on: String, T.Type, (T?) throws -> Bool) rethrows -> DataFrame.Slice`](/documentation/TabularData/DataFrame/Slice/filter(on:_:_:)) Returns a selection of rows that satisfy a predicate in the columns you select by name. ### Creating Two Slices by Splitting Rows ### Creating Two Data Frames by Splitting Rows ### Creating a Data Frame by Sorting a Column ### Creating a Data Frame by Sorting Multiple Columns ### Creating a Data Frame by Joining with Another Data Frame ### Grouping Rows [`struct RowGrouping`](/documentation/TabularData/RowGrouping) A collection of row selections that have the same value in a column. [`func grouped(by: String) -> any RowGroupingProtocol`](/documentation/TabularData/DataFrame/Slice/grouped(by:)) Creates a grouping of rows that the method selects by choosing unique values in a column. [`protocol RowGroupingProtocol`](/documentation/TabularData/RowGroupingProtocol) A type that represents a collection of row selections that have the same value in a column. ### Summarizing a Slice [`func summary() -> DataFrame`](/documentation/TabularData/DataFrame/Slice/summary()) Generates a data frame that summarizes the columns of the data frame slice. [`func summary(of: String...) -> DataFrame`](/documentation/TabularData/DataFrame/Slice/summary(of:)) Generates a data frame that summarizes the columns you select by name. [`func summary(ofColumns: Int...) -> DataFrame`](/documentation/TabularData/DataFrame/Slice/summary(ofColumns:)) Generates a data frame that summarizes the columns you select by index. [`enum SummaryColumnIDs`](/documentation/TabularData/SummaryColumnIDs) The summary data frame column identifiers. ### Saving a Slice to a CSV ### Comparing Slices [`static func == (DataFrame.Slice, DataFrame.Slice) -> Bool`](/documentation/TabularData/DataFrame/Slice/==(_:_:)) Returns a Boolean that indicates whether the slices are equal. ### Describing a Slice [`var description: String`](/documentation/TabularData/DataFrame/Slice/description) A text representation of the data frame slice. [`var debugDescription: String`](/documentation/TabularData/DataFrame/Slice/debugDescription) A text representation of the data frame slice suitable for debugging. [`var customMirror: Mirror`](/documentation/TabularData/DataFrame/Slice/customMirror) A mirror that reflects the data frame slice. ### Hashing a Slice [`func hash(into: inout Hasher)`](/documentation/TabularData/DataFrame/Slice/hash(into:)) Hashes the essential components of the data frame slice by feeding them into a hasher. ### Default Implementations [CustomDebugStringConvertible Implementations](/documentation/TabularData/DataFrame/Slice/CustomDebugStringConvertible-Implementations) [CustomReflectable Implementations](/documentation/TabularData/DataFrame/Slice/CustomReflectable-Implementations) [CustomStringConvertible Implementations](/documentation/TabularData/DataFrame/Slice/CustomStringConvertible-Implementations) [Equatable Implementations](/documentation/TabularData/DataFrame/Slice/Equatable-Implementations) [Hashable Implementations](/documentation/TabularData/DataFrame/Slice/Hashable-Implementations) ## Relationships ### Conforms To [`CustomReflectable`](/documentation/Swift/CustomReflectable) [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`DataFrameProtocol`](/documentation/TabularData/DataFrameProtocol) [`Equatable`](/documentation/Swift/Equatable) [`Copyable`](/documentation/Swift/Copyable) [`Escapable`](/documentation/Swift/Escapable) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`Hashable`](/documentation/Swift/Hashable) --- 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)