ParallelEnumerable.SelectMany<TSource, TCollection, TResult> Method (ParallelQuery<TSource>, Func<TSource, Int32, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)
Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element.
Assemblies: System.Linq.Parallel (in System.Linq.Parallel.dll)
System.Core (in System.Core.dll)
public static ParallelQuery<TResult> SelectMany<TSource, TCollection, TResult>( this ParallelQuery<TSource> source, Func<TSource, int, IEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector )
The type of the intermediate elements collected by collectionSelector.
The type of elements of source.
The type of elements to return.
- Type: System.Linq.ParallelQuery<>
A sequence of values to project.
- Type: System.Func<, Int32, IEnumerable<>>
A transform function to apply to each source element; the second parameter of the function represents the index of the source element.
- Type: System.Func<, , >
A function to create a result element from an element from the first sequence and a collection of matching elements from the second sequence.
Return ValueType: System.Linq.ParallelQuery<>
A sequence whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of source based on the index supplied to collectionSelector, and then mapping each of those sequence elements and their corresponding source element to a result element.
Usage NoteIn Visual Basic and C#, you can call this method as an instance method on any object of type ParallelQuery<>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
source or selector is a null reference (Nothing in Visual Basic).
The query was canceled with the token passed in through WithCancellation.
More than MaxValue elements are enumerated by the query.
One or more exceptions occurred during the evaluation of the query.