Enumerable.ToDictionary(Of TSource, TKey) Method (IEnumerable(Of TSource), Func(Of TSource, TKey), IEqualityComparer(Of TKey))

 

Creates a Dictionary(Of TKey, TValue) from an IEnumerable(Of T) according to a specified key selector function and key comparer.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)

<ExtensionAttribute>
Public Shared Function ToDictionary(Of TSource, TKey) (
	source As IEnumerable(Of TSource),
	keySelector As Func(Of TSource, TKey),
	comparer As IEqualityComparer(Of TKey)
) As Dictionary(Of TKey, TSource)

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.

comparer
Type: System.Collections.Generic.IEqualityComparer(Of TKey)

An IEqualityComparer(Of T) to compare keys.

Return Value

Type: System.Collections.Generic.Dictionary(Of TKey, TSource)

A Dictionary(Of TKey, TValue) that contains keys and values.

Type Parameters

TSource

The type of the elements of source.

TKey

The type of the keys returned by keySelector.

Exception Condition
ArgumentNullException

source or keySelector is null.

-or-

keySelector produces a key that is null.

ArgumentException

keySelector produces duplicate keys for two elements.

If comparer is null, the default equality comparer Default is used to compare keys.

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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