map(_:)
Creates a new column, potentially with missing values, by applying a given thread-safe transform to every row in the data table.
Declaration
func map<T>(_ lazyTransform: @escaping (MLDataTable.Row) -> T?) -> MLDataColumn<T> where T : MLDataValueConvertibleParameters
- lazyTransform:
A thread-safe row transformation function.
The implementation of your transform must accept a row from the data table and return an optional type that conforms to Mldatavalueconvertible. If the transform returns
nilfor a given row, the corresponding element in the new column will have a missing value.
Return Value
A new MLDataColumn.
Discussion
This mapping function is the same as map(_:) with the exception that this version’s lazyTransform parameter returns an optional (T?). Use this version of map() to create empty values by returning nil from your lazyTransform.