# DiscontiguousColumnSlice A collection that represents a selection, potentially with gaps, of elements from a typed column. ``` struct DiscontiguousColumnSlice ``` ## Overview A column slice contains only certain elements from its parent column. Create a slice by selecting certain elements. For example, use [`filter(_:)`](/documentation/TabularData/DiscontiguousColumnSlice/filter(_:)) to create a slice that only includes elements with even values. ```swift let slice = column.filter({ $0.isMultiple(of: 2) }) ``` ## Topics ### Creating a Column Slice [`init(Column)`](/documentation/TabularData/DiscontiguousColumnSlice/init(_:)) Creates a slice with the contents of a column. [`init(column: Column, ranges: [Range])`](/documentation/TabularData/DiscontiguousColumnSlice/init(column:ranges:)) Creates a slice with the contents of a column. ### Creating a Slice of Unique Elements [`func distinct() -> DiscontiguousColumnSlice`](/documentation/TabularData/DiscontiguousColumnSlice/distinct()) Generates a discontiguous slice that contains unique elements. ### Creating a Type-Erased Slice [`func eraseToAnyColumn() -> AnyColumnSlice`](/documentation/TabularData/DiscontiguousColumnSlice/eraseToAnyColumn()) Generates a type-erased copy of the column slice. ### Creating a Column of the Same Type [`var prototype: any AnyColumnPrototype`](/documentation/TabularData/DiscontiguousColumnSlice/prototype) A prototype that creates type-erased columns with the same underlying type as the column slice. ### Creating Transformed Columns [`func map((DiscontiguousColumnSlice.Element) throws -> T?) rethrows -> Column`](/documentation/TabularData/DiscontiguousColumnSlice/map(_:)) Creates a new column by applying a transformation to each element. ### Inspecting a Column Slice [`var name: String`](/documentation/TabularData/DiscontiguousColumnSlice/name) The name of the slice’s parent column. [`var count: Int`](/documentation/TabularData/DiscontiguousColumnSlice/count) The number of elements in the column slice. [`var wrappedElementType: any Any.Type`](/documentation/TabularData/DiscontiguousColumnSlice/wrappedElementType) The underlying type of the column’s elements. [`func argmin() -> Int?`](/documentation/TabularData/DiscontiguousColumnSlice/argmin()) Returns the index of the element with the lowest value, ignoring missing elements. [`func argmax() -> Int?`](/documentation/TabularData/DiscontiguousColumnSlice/argmax()) Returns the index of the element with the highest value, ignoring missing elements. [`func isNil(at: Int) -> Bool`](/documentation/TabularData/DiscontiguousColumnSlice/isNil(at:)) Returns a Boolean that indicates whether the element at the index is missing. ### Accessing Elements [`subscript(Int) -> DiscontiguousColumnSlice.Element`](/documentation/TabularData/DiscontiguousColumnSlice/subscript(_:)-9y37v) Accesses an element at an index. [`subscript(Range) -> DiscontiguousColumnSlice`](/documentation/TabularData/DiscontiguousColumnSlice/subscript(_:)-8rd2f) Accesses a contiguous range of elements. [`subscript(R) -> DiscontiguousColumnSlice`](/documentation/TabularData/DiscontiguousColumnSlice/subscript(_:)-4k2lh) Accesses a contiguous range of elements with a range expression. [`subscript(UnboundedRange) -> DiscontiguousColumnSlice`](/documentation/TabularData/DiscontiguousColumnSlice/subscript(_:)-5xvit) Accesses a contiguous range of elements with an unbounded range. ### Summarizing a Column Slice [`func summary() -> CategoricalSummary`](/documentation/TabularData/DiscontiguousColumnSlice/summary()) Generates a categorical summary of the column slice’s elements. [`func numericSummary() -> NumericSummary`](/documentation/TabularData/DiscontiguousColumnSlice/numericSummary()-3r7pn) Generates a numeric summary of the integer column slice’s elements. [`func numericSummary() -> NumericSummary`](/documentation/TabularData/DiscontiguousColumnSlice/numericSummary()-4b7m0) Generates a numeric summary of the floating-point column slice’s elements. ### Getting Statistical Values [`func sum() -> WrappedElement`](/documentation/TabularData/DiscontiguousColumnSlice/sum()) Returns the sum of the column slice’s elements, ignoring missing elements. [`func min() -> DiscontiguousColumnSlice.Element`](/documentation/TabularData/DiscontiguousColumnSlice/min()) Returns the element with the lowest value, ignoring missing elements. [`func max() -> DiscontiguousColumnSlice.Element`](/documentation/TabularData/DiscontiguousColumnSlice/max()) Returns the element with the highest value, ignoring missing elements. [`func mean() -> DiscontiguousColumnSlice.Element`](/documentation/TabularData/DiscontiguousColumnSlice/mean()-3y11c) Returns the mean average of the floating-point slice’s elements, ignoring missing elements. [`func mean() -> Double?`](/documentation/TabularData/DiscontiguousColumnSlice/mean()-49u93) Returns the mean average of the integer slice’s elements, ignoring missing elements. [`func standardDeviation(deltaDegreesOfFreedom: Int) -> Double?`](/documentation/TabularData/DiscontiguousColumnSlice/standardDeviation(deltaDegreesOfFreedom:)-36nx2) Returns the standard deviation of the integer column slice’s elements, ignoring missing elements. [`func standardDeviation(deltaDegreesOfFreedom: Int) -> DiscontiguousColumnSlice.Element`](/documentation/TabularData/DiscontiguousColumnSlice/standardDeviation(deltaDegreesOfFreedom:)-5vd4r) Returns the standard deviation of the floating-point column slice’s elements, ignoring missing elements. ### Describing a Column Slice [`var description: String`](/documentation/TabularData/DiscontiguousColumnSlice/description) A text representation of the column slice. [`var debugDescription: String`](/documentation/TabularData/DiscontiguousColumnSlice/debugDescription) A text representation of the column slice suitable for debugging. [`var customMirror: Mirror`](/documentation/TabularData/DiscontiguousColumnSlice/customMirror) A mirror that reflects the column slice. ### Comparing Two Column Slices [`static func == (DiscontiguousColumnSlice, DiscontiguousColumnSlice) -> Bool`](/documentation/TabularData/DiscontiguousColumnSlice/==(_:_:)) Returns a Boolean that indicates whether the column slices are equal. ### Modifying a Column Slice with a Value [`static func += (inout DiscontiguousColumnSlice, WrappedElement)`](/documentation/TabularData/DiscontiguousColumnSlice/+=(_:_:)-1mzz0) Modifies a column slice by adding a value to each element. [`static func -= (inout DiscontiguousColumnSlice, WrappedElement)`](/documentation/TabularData/DiscontiguousColumnSlice/-=(_:_:)-2yrui) Modifies a column slice by subtracting a value from each element. [`static func *= (inout DiscontiguousColumnSlice, WrappedElement)`](/documentation/TabularData/DiscontiguousColumnSlice/*=(_:_:)-7gcqc) Modifies a column slice by multiplying each element by a value. [`static func /= (inout DiscontiguousColumnSlice, WrappedElement)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-1g0yb) Modifies an integer column slice by dividing each element by a value. [`static func /= (inout DiscontiguousColumnSlice, WrappedElement)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-6i7hx) Modifies a floating-point column slice by dividing each element by a value. ### Modifying a Column Slice with a Collection of Values [`static func += (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/+=(_:_:)-2jxz1) Modifies a column slice by adding each value in a collection to the corresponding element in the column. [`static func += (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/+=(_:_:)-lpai) Modifies a column slice by adding each optional value in a collection to the corresponding element in the column. [`static func -= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/-=(_:_:)-9nkq6) Modifies a column slice by subtracting each value in a collection from the corresponding element in the column. [`static func -= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/-=(_:_:)-8a20q) Modifies a column slice by subtracting each optional value in a collection from the corresponding element in the column. [`static func *= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/*=(_:_:)-9jg9h) Modifies a column slice by multiplying each element in the column by the corresponding value in a collection. [`static func *= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/*=(_:_:)-18nlr) Modifies a column slice by multiplying each element in the column by the corresponding optional value in a collection. [`static func /= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-6xf9s) Modifies an integer column slice by dividing each element in the column by the corresponding value in a collection. [`static func /= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-1mzcg) Modifies an integer column slice by dividing each element in the column by the corresponding optional value in a collection. [`static func /= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-39wsi) Modifies a floating-point column slice by dividing each element in the column by the corresponding value in a collection. [`static func /= (inout DiscontiguousColumnSlice, C)`](/documentation/TabularData/DiscontiguousColumnSlice/_=(_:_:)-6lzj) Modifies a floating-point column slice by dividing each element in the column by the corresponding optional value in a collection. ### Generating a Column by Combining Two Column Slices ### Generating a Column by Adding a Value ### Generating a Column by Subtracting a Value ### Generating a Column by Multiplying a Value ### Generating a Column by Dividing a Value ### Hashing a Column Slice [`func hash(into: inout Hasher)`](/documentation/TabularData/DiscontiguousColumnSlice/hash(into:)) Hashes the essential components of the column slice by feeding them into a hasher. ### Supporting Types [`typealias Element`](/documentation/TabularData/DiscontiguousColumnSlice/Element) The type of the column slice’s elements. [`typealias Index`](/documentation/TabularData/DiscontiguousColumnSlice/Index) The type that represents a position in the column slice. ### Invoking Protocol Methods ### Instance Properties [`var missingCount: Int`](/documentation/TabularData/DiscontiguousColumnSlice/missingCount) The number of missing elements in the column slice. ### Default Implementations [BidirectionalCollection Implementations](/documentation/TabularData/DiscontiguousColumnSlice/BidirectionalCollection-Implementations) [Collection Implementations](/documentation/TabularData/DiscontiguousColumnSlice/Collection-Implementations) [CustomDebugStringConvertible Implementations](/documentation/TabularData/DiscontiguousColumnSlice/CustomDebugStringConvertible-Implementations) [CustomReflectable Implementations](/documentation/TabularData/DiscontiguousColumnSlice/CustomReflectable-Implementations) [CustomStringConvertible Implementations](/documentation/TabularData/DiscontiguousColumnSlice/CustomStringConvertible-Implementations) [Equatable Implementations](/documentation/TabularData/DiscontiguousColumnSlice/Equatable-Implementations) [Hashable Implementations](/documentation/TabularData/DiscontiguousColumnSlice/Hashable-Implementations) ## Relationships ### Conforms To [`BidirectionalCollection`](/documentation/Swift/BidirectionalCollection) [`Sendable`](/documentation/Swift/Sendable) [`Equatable`](/documentation/Swift/Equatable) [`Hashable`](/documentation/Swift/Hashable) [`MutableCollection`](/documentation/Swift/MutableCollection) [`Collection`](/documentation/Swift/Collection) [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`OptionalColumnProtocol`](/documentation/TabularData/OptionalColumnProtocol) [`Escapable`](/documentation/Swift/Escapable) [`CustomReflectable`](/documentation/Swift/CustomReflectable) [`ColumnProtocol`](/documentation/TabularData/ColumnProtocol) [`Sequence`](/documentation/Swift/Sequence) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`Copyable`](/documentation/Swift/Copyable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- Copyright © 2026 Apple Inc. 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