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IGrouping<TKey, TElement> Interface

 

Represents a collection of objects that have a common key.

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

public interface IGrouping<out TKey, out TElement> : IEnumerable<TElement>, 
	IEnumerable

Type Parameters

outTKey

The type of the key of the IGrouping<TKey, TElement>.

outTElement

The type of the values in the IGrouping<TKey, TElement>.

NameDescription
System_CAPS_pubpropertyKey

Gets the key of the IGrouping<TKey, TElement>.

NameDescription
System_CAPS_pubmethodGetEnumerator()

Returns an enumerator that iterates through the collection.(Inherited from IEnumerable<T>.)

NameDescription
System_CAPS_pubmethodAggregate<TElement>(Func<TElement, TElement, TElement>)

Overloaded. Applies an accumulator function over a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAggregate<TElement, TAccumulate>(TAccumulate, Func<TAccumulate, TElement, TAccumulate>)

Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.(Defined by Enumerable.)

System_CAPS_pubmethodAggregate<TElement, TAccumulate, TResult>(TAccumulate, Func<TAccumulate, TElement, TAccumulate>, Func<TAccumulate, TResult>)

Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.(Defined by Enumerable.)

System_CAPS_pubmethodAll<TElement>(Func<TElement, Boolean>)

Determines whether all elements of a sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethodAny<TElement>()

Overloaded. Determines whether a sequence contains any elements.(Defined by Enumerable.)

System_CAPS_pubmethodAny<TElement>(Func<TElement, Boolean>)

Overloaded. Determines whether any element of a sequence satisfies a condition.(Defined by Enumerable.)

System_CAPS_pubmethodAsEnumerable<TElement>()

Returns the input typed as IEnumerable<T>.(Defined by Enumerable.)

System_CAPS_pubmethodAsParallel()

Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)

System_CAPS_pubmethodAsParallel<TElement>()

Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)

System_CAPS_pubmethodAsQueryable()

Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)

System_CAPS_pubmethodAsQueryable<TElement>()

Overloaded. Converts a generic IEnumerable<T> to a generic IQueryable<T>.(Defined by Queryable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Decimal>)

Overloaded. Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Double>)

Overloaded. Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Int32>)

Overloaded. Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Int64>)

Overloaded. Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Nullable<Decimal>>)

Overloaded. Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Nullable<Double>>)

Overloaded. Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Nullable<Int32>>)

Overloaded. Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Nullable<Int64>>)

Overloaded. Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Nullable<Single>>)

Overloaded. Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodAverage<TElement>(Func<TElement, Single>)

Overloaded. Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodCast<TResult>()

Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)

System_CAPS_pubmethodConcat<TElement>(IEnumerable<TElement>)

Concatenates two sequences.(Defined by Enumerable.)

System_CAPS_pubmethodContains<TElement>(TElement)

Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer.(Defined by Enumerable.)

System_CAPS_pubmethodContains<TElement>(TElement, IEqualityComparer<TElement>)

Overloaded. Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.(Defined by Enumerable.)

System_CAPS_pubmethodCount<TElement>()

Overloaded. Returns the number of elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodCount<TElement>(Func<TElement, Boolean>)

Overloaded. Returns a number that represents how many elements in the specified sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethodDefaultIfEmpty<TElement>()

Overloaded. Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.(Defined by Enumerable.)

System_CAPS_pubmethodDefaultIfEmpty<TElement>(TElement)

Overloaded. Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty.(Defined by Enumerable.)

System_CAPS_pubmethodDistinct<TElement>()

Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodDistinct<TElement>(IEqualityComparer<TElement>)

Overloaded. Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodElementAt<TElement>(Int32)

Returns the element at a specified index in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodElementAtOrDefault<TElement>(Int32)

Returns the element at a specified index in a sequence or a default value if the index is out of range.(Defined by Enumerable.)

System_CAPS_pubmethodExcept<TElement>(IEnumerable<TElement>)

Overloaded. Produces the set difference of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodExcept<TElement>(IEnumerable<TElement>, IEqualityComparer<TElement>)

Overloaded. Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodFirst<TElement>()

Overloaded. Returns the first element of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodFirst<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the first element in a sequence that satisfies a specified condition.(Defined by Enumerable.)

System_CAPS_pubmethodFirstOrDefault<TElement>()

Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)

System_CAPS_pubmethodFirstOrDefault<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey>(Func<TElement, TKey>)

Overloaded. Groups the elements of a sequence according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey>(Func<TElement, TKey>, IEqualityComparer<TKey>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>, IEqualityComparer<TKey>)

Overloaded. Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TResult>(Func<TElement, TKey>, Func<TKey, IEnumerable<TElement>, TResult>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TResult>(Func<TElement, TKey>, Func<TKey, IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TElement, TResult>(Func<TElement, TKey>, Func<TElement, TElement>, Func<TKey, IEnumerable<TElement>, TResult>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethodGroupBy<TElement, TKey, TElement, TResult>(Func<TElement, TKey>, Func<TElement, TElement>, Func<TKey, IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>)

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethodGroupJoin<TElement, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TElement, TKey>, Func<TInner, TKey>, Func<TElement, IEnumerable<TInner>, TResult>)

Overloaded. Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethodGroupJoin<TElement, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TElement, TKey>, Func<TInner, TKey>, Func<TElement, IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>)

Overloaded. Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer<T> is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethodIntersect<TElement>(IEnumerable<TElement>)

Overloaded. Produces the set intersection of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodIntersect<TElement>(IEnumerable<TElement>, IEqualityComparer<TElement>)

Overloaded. Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)

System_CAPS_pubmethodJoin<TElement, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TElement, TKey>, Func<TInner, TKey>, Func<TElement, TInner, TResult>)

Overloaded. Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethodJoin<TElement, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TElement, TKey>, Func<TInner, TKey>, Func<TElement, TInner, TResult>, IEqualityComparer<TKey>)

Overloaded. Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer<T> is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethodLast<TElement>()

Overloaded. Returns the last element of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodLast<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the last element of a sequence that satisfies a specified condition.(Defined by Enumerable.)

System_CAPS_pubmethodLastOrDefault<TElement>()

Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)

System_CAPS_pubmethodLastOrDefault<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)

System_CAPS_pubmethodLongCount<TElement>()

Overloaded. Returns an Int64 that represents the total number of elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodLongCount<TElement>(Func<TElement, Boolean>)

Overloaded. Returns an Int64 that represents how many elements in a sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>()

Overloaded. Returns the maximum value in a generic sequence.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Decimal>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Double>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Double value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Int32>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Int64>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Nullable<Decimal>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Nullable<Double>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Double value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Nullable<Int32>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Nullable<Int64>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Nullable<Single>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Single value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement>(Func<TElement, Single>)

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Single value.(Defined by Enumerable.)

System_CAPS_pubmethodMax<TElement, TResult>(Func<TElement, TResult>)

Overloaded. Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>()

Overloaded. Returns the minimum value in a generic sequence.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Decimal>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Double>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Double value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Int32>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Int64>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Nullable<Decimal>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Nullable<Double>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Double value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Nullable<Int32>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Nullable<Int64>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Nullable<Single>>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Single value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement>(Func<TElement, Single>)

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Single value.(Defined by Enumerable.)

System_CAPS_pubmethodMin<TElement, TResult>(Func<TElement, TResult>)

Overloaded. Invokes a transform function on each element of a generic sequence and returns the minimum resulting value.(Defined by Enumerable.)

System_CAPS_pubmethodOfType<TResult>()

Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)

System_CAPS_pubmethodOrderBy<TElement, TKey>(Func<TElement, TKey>)

Overloaded. Sorts the elements of a sequence in ascending order according to a key.(Defined by Enumerable.)

System_CAPS_pubmethodOrderBy<TElement, TKey>(Func<TElement, TKey>, IComparer<TKey>)

Overloaded. Sorts the elements of a sequence in ascending order by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethodOrderByDescending<TElement, TKey>(Func<TElement, TKey>)

Overloaded. Sorts the elements of a sequence in descending order according to a key.(Defined by Enumerable.)

System_CAPS_pubmethodOrderByDescending<TElement, TKey>(Func<TElement, TKey>, IComparer<TKey>)

Overloaded. Sorts the elements of a sequence in descending order by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethodReverse<TElement>()

Inverts the order of the elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSelect<TElement, TResult>(Func<TElement, TResult>)

Overloaded. Projects each element of a sequence into a new form.(Defined by Enumerable.)

System_CAPS_pubmethodSelect<TElement, TResult>(Func<TElement, Int32, TResult>)

Overloaded. Projects each element of a sequence into a new form by incorporating the element's index.(Defined by Enumerable.)

System_CAPS_pubmethodSelectMany<TElement, TResult>(Func<TElement, IEnumerable<TResult>>)

Overloaded. Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSelectMany<TElement, TResult>(Func<TElement, Int32, IEnumerable<TResult>>)

Overloaded. Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element.(Defined by Enumerable.)

System_CAPS_pubmethodSelectMany<TElement, TCollection, TResult>(Func<TElement, IEnumerable<TCollection>>, Func<TElement, TCollection, TResult>)

Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.(Defined by Enumerable.)

System_CAPS_pubmethodSelectMany<TElement, TCollection, TResult>(Func<TElement, Int32, IEnumerable<TCollection>>, Func<TElement, TCollection, TResult>)

Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element.(Defined by Enumerable.)

System_CAPS_pubmethodSequenceEqual<TElement>(IEnumerable<TElement>)

Overloaded. Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.(Defined by Enumerable.)

System_CAPS_pubmethodSequenceEqual<TElement>(IEnumerable<TElement>, IEqualityComparer<TElement>)

Overloaded. Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>.(Defined by Enumerable.)

System_CAPS_pubmethodSingle<TElement>()

Overloaded. Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSingle<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists.(Defined by Enumerable.)

System_CAPS_pubmethodSingleOrDefault<TElement>()

Overloaded. Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSingleOrDefault<TElement>(Func<TElement, Boolean>)

Overloaded. Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.(Defined by Enumerable.)

System_CAPS_pubmethodSkip<TElement>(Int32)

Bypasses a specified number of elements in a sequence and then returns the remaining elements.(Defined by Enumerable.)

System_CAPS_pubmethodSkipWhile<TElement>(Func<TElement, Boolean>)

Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.(Defined by Enumerable.)

System_CAPS_pubmethodSkipWhile<TElement>(Func<TElement, Int32, Boolean>)

Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Decimal>)

Overloaded. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Double>)

Overloaded. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Int32>)

Overloaded. Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Int64>)

Overloaded. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Nullable<Decimal>>)

Overloaded. Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Nullable<Double>>)

Overloaded. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Nullable<Int32>>)

Overloaded. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Nullable<Int64>>)

Overloaded. Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Nullable<Single>>)

Overloaded. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodSum<TElement>(Func<TElement, Single>)

Overloaded. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethodTake<TElement>(Int32)

Returns a specified number of contiguous elements from the start of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethodTakeWhile<TElement>(Func<TElement, Boolean>)

Overloaded. Returns elements from a sequence as long as a specified condition is true.(Defined by Enumerable.)

System_CAPS_pubmethodTakeWhile<TElement>(Func<TElement, Int32, Boolean>)

Overloaded. Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethodToArray<TElement>()

Creates an array from a IEnumerable<T>.(Defined by Enumerable.)

System_CAPS_pubmethodToDictionary<TElement, TKey>(Func<TElement, TKey>)

Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethodToDictionary<TElement, TKey>(Func<TElement, TKey>, IEqualityComparer<TKey>)

Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function and key comparer.(Defined by Enumerable.)

System_CAPS_pubmethodToDictionary<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>)

Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to specified key selector and element selector functions.(Defined by Enumerable.)

System_CAPS_pubmethodToDictionary<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>, IEqualityComparer<TKey>)

Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function.(Defined by Enumerable.)

System_CAPS_pubmethodToList<TElement>()

Creates a List<T> from an IEnumerable<T>.(Defined by Enumerable.)

System_CAPS_pubmethodToLookup<TElement, TKey>(Func<TElement, TKey>)

Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethodToLookup<TElement, TKey>(Func<TElement, TKey>, IEqualityComparer<TKey>)

Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function and key comparer.(Defined by Enumerable.)

System_CAPS_pubmethodToLookup<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>)

Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to specified key selector and element selector functions.(Defined by Enumerable.)

System_CAPS_pubmethodToLookup<TElement, TKey, TElement>(Func<TElement, TKey>, Func<TElement, TElement>, IEqualityComparer<TKey>)

Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function.(Defined by Enumerable.)

System_CAPS_pubmethodUnion<TElement>(IEnumerable<TElement>)

Overloaded. Produces the set union of two sequences by using the default equality comparer.(Defined by Enumerable.)

System_CAPS_pubmethodUnion<TElement>(IEnumerable<TElement>, IEqualityComparer<TElement>)

Overloaded. Produces the set union of two sequences by using a specified IEqualityComparer<T>.(Defined by Enumerable.)

System_CAPS_pubmethodWhere<TElement>(Func<TElement, Boolean>)

Overloaded. Filters a sequence of values based on a predicate.(Defined by Enumerable.)

System_CAPS_pubmethodWhere<TElement>(Func<TElement, Int32, Boolean>)

Overloaded. Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethodZip<TElement, TSecond, TResult>(IEnumerable<TSecond>, Func<TElement, TSecond, TResult>)

Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results.(Defined by Enumerable.)

An IGrouping<TKey, TElement> is an IEnumerable<T> that additionally has a key. The key represents the attribute that is common to each value in the IGrouping<TKey, TElement>.

The values of an IGrouping<TKey, TElement> are accessed much as the elements of an IEnumerable<T> are accessed. For example, you can access the values by using a foreach in Visual C# or For Each in Visual Basic loop to iterate through the IGrouping<TKey, TElement> object. The Example section contains a code example that shows you how to access both the key and the values of an IGrouping<TKey, TElement> object.

The IGrouping<TKey, TElement> type is used by the GroupBy standard query operator methods, which return a sequence of elements of type IGrouping<TKey, TElement>.

The following example demonstrates how to work with an IGrouping<TKey, TElement> object.

In this example, GroupBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>) is called on the array of MemberInfo objects returned by GetMembers. GroupBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>) groups the objects based on the value of their MemberType property. Each unique value for MemberType in the array of MemberInfo objects becomes a key for a new IGrouping<TKey, TElement> object, and the MemberInfo objects that have that key form the IGrouping<TKey, TElement> object's sequence of values.

Finally, the First<TSource> method is called on the sequence of IGrouping<TKey, TElement> objects to obtain just the first IGrouping<TKey, TElement> object.

The example then outputs the key of the IGrouping<TKey, TElement> object and the Name property of each value in the IGrouping<TKey, TElement> object's sequence of values. Notice that to access an IGrouping<TKey, TElement> object's sequence of values, you simply use the IGrouping<TKey, TElement> variable itself.

// Get an IGrouping object.
IGrouping<System.Reflection.MemberTypes, System.Reflection.MemberInfo> group =
    typeof(String).GetMembers().
    GroupBy(member => member.MemberType).
    First();

// Output the key of the IGrouping, then iterate
// through each value in the sequence of values
// of the IGrouping and output its Name property.
Console.WriteLine("\nValues that have the key '{0}':", group.Key);
foreach (System.Reflection.MemberInfo mi in group)
    Console.WriteLine(mi.Name);

// The output is similar to:

// Values that have the key 'Method':
// get_Chars
// get_Length
// IndexOf
// IndexOfAny
// LastIndexOf
// LastIndexOfAny
// Insert
// Replace
// Replace
// Remove
// Join
// Join
// Equals
// Equals
// Equals
// ...

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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