,System.Func{--0,--1})} ,System.Func{--0,--1},System.Collections.Generic.IEqualityComparer{--1})}

ObservableAsync.DistinctUntilChangedBy(IObservableAsync, Func) method¶

Defined in

Type: ObservableAsync Namespace: ReactiveUI.Extensions.Async Assembly: ReactiveUI.Extensions.dll

Applies to

net10.0, net10.0-browserwasm1.0, net10.0-desktop1.0, net9.0, net9.0-browserwasm1.0, net9.0-desktop1.0, net8.0, net8.0-ios17.5, net8.0-maccatalyst17.5, net8.0-macos14.2, net8.0-macos14.5, net8.0-tvos17.2, netstandard2.1, net462, net481

Overloads¶

1. public static IObservableAsync<T> DistinctUntilChangedBy<T, TKey>(this IObservableAsync<T> @this, Func<T, TKey> keySelector)
2. public static IObservableAsync<T> DistinctUntilChangedBy<T, TKey>(this IObservableAsync<T> @this, Func<T, TKey> keySelector, IEqualityComparer<TKey> equalityComparer)

1. Overload¶

public static IObservableAsync<T> DistinctUntilChangedBy<T, TKey>(this IObservableAsync<T> @this, Func<T, TKey> keySelector)

View source

Summary: Returns an observable sequence that emits elements from the source sequence, suppressing consecutive duplicates as determined by a key selector function.

Type parameters

Name	Description
`T`	The type of the elements in the source sequence.
`TKey`	The type of the key used to determine whether consecutive elements are considered duplicates.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.
`keySelector`	Func	A function that extracts the comparison key from each element in the source sequence.

Returns: IObservableAsync -- An observable sequence that contains only the elements from the source sequence that are not consecutive duplicates according to the specified key.

Remarks

The comparison of keys uses the default equality comparer for the type TKey. Only consecutive duplicate elements are suppressed; non-consecutive duplicates are not affected.

2. Overload¶

public static IObservableAsync<T> DistinctUntilChangedBy<T, TKey>(this IObservableAsync<T> @this, Func<T, TKey> keySelector, IEqualityComparer<TKey> equalityComparer)

View source

Summary: Returns an observable sequence that emits elements from the source sequence, suppressing consecutive duplicates as determined by a key selector and equality comparer.

Type parameters

Name	Description
`T`	The type of the elements in the source sequence.
`TKey`	The type of the key used to determine whether consecutive elements are considered duplicates.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.
`keySelector`	Func	A function that extracts the comparison key from each element in the source sequence.
`equalityComparer`	IEqualityComparer	An equality comparer used to compare keys for equality.

Returns: IObservableAsync -- An observable sequence that contains only the elements from the source sequence that are not consecutive duplicates according to the specified key and comparer.

Remarks

The first element in the sequence is always emitted. Subsequent elements are emitted only if their key, as determined by keySelector, is not equal to the key of the immediately preceding element, as determined by equalityComparer.

Exceptions

Type	Condition
System.ArgumentNullException	Thrown if `keySelector` or `equalityComparer` is null.