Enumerable.ToDictionary(Of TSource, TKey, TElement) Method (IEnumerable(Of TSource), Func(Of TSource, TKey), Func(Of TSource, TElement))
[ 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 specified key selector and element selector functions.
Assembly: System.Core (in System.Core.dll)
'Declaration <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) _ ) As Dictionary(Of TKey, TElement)
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.
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.| Exception | Condition |
|---|---|
| ArgumentNullException | source or keySelector or elementSelector is Nothing. -or- keySelector produces a key that is Nothing. |
| ArgumentException | keySelector produces duplicate keys for two elements. |
The ToDictionary(Of TSource, TKey, TElement)(IEnumerable(Of TSource), Func(Of TSource, TKey), Func(Of TSource, TElement)) method uses the default equality comparer Default to compare keys.