Enumerable.ToDictionary<(Of <(TSource, TKey, TElement>)>) Method (IEnumerable<(Of <(TSource>)>), Func<(Of <(TSource, TKey>)>), Func<(Of <(TSource, TElement>)>), IEqualityComparer<(Of <(TKey>)>))
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Creates a Dictionary<(Of <(TKey, TValue>)>) from an IEnumerable<(Of <(T>)>) according to a specified key selector function, a comparer, and an element selector function.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Syntax
<ExtensionAttribute> _
Public Shared Function ToDictionary(Of TSource, TKey, TElement) ( _
source As IEnumerable(Of TSource), _
keySelector As Func(Of TSource, TKey), _
elementSelector As Func(Of TSource, TElement), _
comparer As IEqualityComparer(Of TKey) _
) As Dictionary(Of TKey, TElement)
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TSource, TElement> elementSelector,
IEqualityComparer<TKey> comparer
)
Type Parameters
- TSource
The type of the elements of source.
- TKey
The type of the key returned by keySelector.
- TElement
The type of the value returned by elementSelector.
Parameters
- source
Type: System.Collections.Generic..::.IEnumerable<(Of <(TSource>)>)
An IEnumerable<(Of <(T>)>) to create a Dictionary<(Of <(TKey, TValue>)>) from.
- keySelector
Type: System..::.Func<(Of <(TSource, TKey>)>)
A function to extract a key from each element.
- elementSelector
Type: System..::.Func<(Of <(TSource, TElement>)>)
A transform function to produce a result element value from each element.
- comparer
Type: System.Collections.Generic..::.IEqualityComparer<(Of <(TKey>)>)
An IEqualityComparer<(Of <(T>)>) to compare keys.
Return Value
Type: System.Collections.Generic..::.Dictionary<(Of <(TKey, TElement>)>)
A Dictionary<(Of <(TKey, TValue>)>) that contains values of type TElement selected from the input sequence.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<(Of <(TSource>)>). When you use instance method syntax to call this method, omit the first parameter.
Exceptions
Exception | Condition |
---|---|
ArgumentNullException | source or keySelector or elementSelector is nullNothingnullptra null reference (Nothing in Visual Basic). -or- keySelector produces a key that is nullNothingnullptra null reference (Nothing in Visual Basic). |
ArgumentException | keySelector produces duplicate keys for two elements. |
Remarks
If comparer is nullNothingnullptra null reference (Nothing in Visual Basic), the default equality comparer Default is used to compare keys.
Version Information
Windows Phone OS
Supported in: 8.1, 8.0, 7.1, 7.0
Platforms
Windows Phone