C1.LiveLinq.IndexedQueryExtensions.GroupBy
GroupBy Method
GroupBy<TSource, TKey, TElement, TResult>(IIndexedSource<TSource>, Expression<Func<TSource, TKey>>, Expression<Func<TSource, TElement>>, Expression<Func<TKey, IEnumerable<TElement>, TResult>>)
Groups the elements of a collection 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.
Declaration
public static IIndexedSource<TResult> GroupBy<TSource, TKey, TElement, TResult>(this IIndexedSource<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TSource, TElement>> elementSelector, Expression<Func<TKey, IEnumerable<TElement>, TResult>> resultSelector)Public Shared Function GroupBy(Of TSource, TKey, TElement, TResult)(source As IIndexedSource(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), elementSelector As Expression(Of Func(Of TSource, TElement)), resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TElement), TResult))) As IIndexedSource(Of TResult)Parameters
| Type | Name | Description |
|---|---|---|
| IIndexedSource<TSource> | source | An IIndexedSource<T> whose elements to group |
| Expression<Func<TSource, TKey>> | keySelector | A function to extract the key for each element. |
| Expression<Func<TSource, TElement>> | elementSelector | A function to map each source element to an element in the IGrouping<TKey, TElement>. |
| Expression<Func<TKey, IEnumerable<TElement>, TResult>> | resultSelector | A function to create a result value from each group. |
Returns
| Type | Description |
|---|---|
| IIndexedSource<TResult> | A collection of elements of type TResult where each element represents a projection over a group and its key. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of source. |
| TKey | The type of the key returned by keySelector. |
| TElement | The type of the elements in the IGrouping<TKey, TElement>. |
| TResult | The type of the result value returned by resultSelector |
GroupBy<TSource, TKey, TElement>(IIndexedSource<TSource>, Expression<Func<TSource, TKey>>, Expression<Func<TSource, TElement>>)
Groups the elements of a collection according to a specified key selector function and projects the elements for each group by using a specified function.
Declaration
public static IIndexedSource<IGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IIndexedSource<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TSource, TElement>> elementSelector)Public Shared Function GroupBy(Of TSource, TKey, TElement)(source As IIndexedSource(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), elementSelector As Expression(Of Func(Of TSource, TElement))) As IIndexedSource(Of IGrouping(Of TKey, TElement))Parameters
| Type | Name | Description |
|---|---|---|
| IIndexedSource<TSource> | source | An IIndexedSource<T> whose elements to group |
| Expression<Func<TSource, TKey>> | keySelector | A function to extract the key for each element. |
| Expression<Func<TSource, TElement>> | elementSelector | A function to map each source element to an element in the IGrouping<TKey, TElement>. |
Returns
| Type | Description |
|---|---|
| IIndexedSource<IGrouping<TKey, TElement>> | A collection of IGrouping<TKey, TElement> objects each containing a collection of objects of type TElement and a key. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of source. |
| TKey | The type of the key returned by keySelector. |
| TElement | The type of the elements in the IGrouping<TKey, TElement>. |
GroupBy<TSource, TKey, TResult>(IIndexedSource<TSource>, Expression<Func<TSource, TKey>>, Expression<Func<TKey, IEnumerable<TSource>, TResult>>)
Groups the elements of a collection according to a specified key selector function and creates a result value from each group and its key.
Declaration
public static IIndexedSource<TResult> GroupBy<TSource, TKey, TResult>(this IIndexedSource<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TKey, IEnumerable<TSource>, TResult>> resultSelector)Public Shared Function GroupBy(Of TSource, TKey, TResult)(source As IIndexedSource(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TSource), TResult))) As IIndexedSource(Of TResult)Parameters
| Type | Name | Description |
|---|---|---|
| IIndexedSource<TSource> | source | An IIndexedSource<T> whose elements to group |
| Expression<Func<TSource, TKey>> | keySelector | A function to extract the key for each element. |
| Expression<Func<TKey, IEnumerable<TSource>, TResult>> | resultSelector | A function to create a result value from each group. |
Returns
| Type | Description |
|---|---|
| IIndexedSource<TResult> | A collection of elements of type TResult where each element represents a projection over a group and its key. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of source. |
| TKey | The type of the key returned by keySelector. |
| TResult | The type of the result value returned by resultSelector |
GroupBy<TSource, TKey>(IIndexedSource<TSource>, Expression<Func<TSource, TKey>>)
Groups the elements of a collection according to a specified key selector function.
Declaration
public static IIndexedSource<IGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IIndexedSource<TSource> source, Expression<Func<TSource, TKey>> keySelector)Public Shared Function GroupBy(Of TSource, TKey)(source As IIndexedSource(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey))) As IIndexedSource(Of IGrouping(Of TKey, TSource))Parameters
| Type | Name | Description |
|---|---|---|
| IIndexedSource<TSource> | source | An IIndexedSource<T> whose elements to group |
| Expression<Func<TSource, TKey>> | keySelector | A function to extract the key for each element. |
Returns
| Type | Description |
|---|---|
| IIndexedSource<IGrouping<TKey, TSource>> | A collection of IGrouping<TKey, TElement> objects each containing a sequence of objects and a key. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of source. |
| TKey | The type of the key returned by keySelector. |