Method Lead

Lead<TSource>(IAsyncEnumerable<TSource>, int)

Produces a projection of a sequence by evaluating pairs of elements separated by a negative offset.

Declaration

public static IAsyncEnumerable<(TSource current, TSource? lead)> Lead<TSource>(this IAsyncEnumerable<TSource> source, int offset)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The sequence over which to evaluate lag
int	offset	The offset (expressed as a positive number) by which to lag each value of the sequence

Returns

Type	Description
IAsyncEnumerable<(TSource current, TSource lag)>	A sequence of tuples with the current and lagged elements

Type Parameters

Name	Description
TSource	The type of the elements of the source sequence

Remarks

This operator evaluates in a deferred and streaming manner.
For elements prior to the lag offset, default(TSource?) is used as the lagged value.

Lead<TSource, TResult>(IAsyncEnumerable<TSource>, int, Func<TSource, TSource?, TResult>)

Produces a projection of a sequence by evaluating pairs of elements separated by a positive offset.

Declaration

public static IAsyncEnumerable<TResult> Lead<TSource, TResult>(this IAsyncEnumerable<TSource> source, int offset, Func<TSource, TSource?, TResult> resultSelector)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The sequence over which to evaluate Lead
int	offset	The offset (expressed as a positive number) by which to lead each element of the sequence
Func<TSource, TSource, TResult>	resultSelector	A projection function which accepts the current and subsequent (lead) element (in that order) and produces a result

Returns

Type	Description
IAsyncEnumerable<TResult>	A sequence produced by projecting each element of the sequence with its lead pairing

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TResult	The type of the elements in the result sequence

Remarks

This operator evaluates in a deferred and streaming manner.
For elements of the sequence that are less than offset items from the end, default(TSource?) is used as the lead value.

Lead<TSource, TResult>(IAsyncEnumerable<TSource>, int, TSource, Func<TSource, TSource, TResult>)

Produces a projection of a sequence by evaluating pairs of elements separated by a positive offset.

Declaration

public static IAsyncEnumerable<TResult> Lead<TSource, TResult>(this IAsyncEnumerable<TSource> source, int offset, TSource defaultLeadValue, Func<TSource, TSource, TResult> resultSelector)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The sequence over which to evaluate Lead
int	offset	The offset (expressed as a positive number) by which to lead each element of the sequence
TSource	defaultLeadValue	A default value supplied for the leading element when none is available
Func<TSource, TSource, TResult>	resultSelector	A projection function which accepts the current and subsequent (lead) element (in that order) and produces a result

Returns

Type	Description
IAsyncEnumerable<TResult>	A sequence produced by projecting each element of the sequence with its lead pairing

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TResult	The type of the elements in the result sequence

Remarks

This operator evaluates in a deferred and streaming manner.

Lead<TSource, TResult>(IAsyncEnumerable<TSource>, int, TSource, Func<TSource, TSource, ValueTask<TResult>>)

Produces a projection of a sequence by evaluating pairs of elements separated by a positive offset.

Declaration

public static IAsyncEnumerable<TResult> Lead<TSource, TResult>(this IAsyncEnumerable<TSource> source, int offset, TSource defaultLeadValue, Func<TSource, TSource, ValueTask<TResult>> resultSelector)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The sequence over which to evaluate Lead
int	offset	The offset (expressed as a positive number) by which to lead each element of the sequence
TSource	defaultLeadValue	A default value supplied for the leading element when none is available
Func<TSource, TSource, ValueTask<TResult>>	resultSelector	A projection function which accepts the current and subsequent (lead) element (in that order) and produces a result

Returns

Type	Description
IAsyncEnumerable<TResult>	A sequence produced by projecting each element of the sequence with its lead pairing

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TResult	The type of the elements in the result sequence

Remarks

This operator evaluates in a deferred and streaming manner.