Operator name |
Description |
---|---|
OfType | Selects values, depending on their ability to be cast to a specified type. |
Where | Selects values, depending on a predicate function. |
Operator name |
Description |
---|---|
Select | Selects values, depending on a selector function. |
SelectMany | Selects values, depending on a selector function, and combines resulting sequences into one sequence. SelectMany performs a one-to-many element projection over a sequence. It differs from Select in that the selector function is expected to return a sequence that is then expanded. |
Operator name |
Description |
---|---|
Skip | Skips n elements from a sequence. |
SkipWhile | Skips elements based on a predicate function until an element does not satisfy the condition. |
Take | Takes n elements from a sequence. |
TakeWhile | Takes elements based on a predicate function until an element does not satisfy the condition. |
Operator name |
Description |
---|---|
GroupJoin | Joins two sequences based on key selector functions and groups the resulting matches for each element. |
Join | Joins two sequences based on key selector functions and extracts pairs of values. |
Operator name |
Description |
---|---|
Concat | Concatenates two sequences to form one sequence. |
Operator name |
Description |
---|---|
OrderBy | Sorts values in ascending order. |
OrderByDescending | Sorts values in descending order. |
ThenBy | Performs a secondary sort in ascending order. |
ThenByDescending | Performs a secondary sort in descending order. |
Reverse | Reverses the order of the elements in a sequence. |
Operator name |
Description |
---|---|
GroupBy | Groups elements that share a common attribute. Each group is represented by an IGrouping<TKey, TElement> object. |
ToLookup | Inserts elements into a Lookup<TKey, TElement> (a one-to-many dictionary) based on a key selector function. |
Operator name |
Description |
---|---|
Distinct | Removes duplicate values from a collection. |
Except | Returns the set difference, which means the elements of one sequence that do not appear in a second sequence. |
Intersect | Returns the set intersection, which means elements that appear in each of two sequences. |
Union | Returns the set union, which means unique elements that appear in either of two sequences. |
Operator name |
Description |
---|---|
AsEnumerable | Returns the input typed as IEnumerable<T>. |
AsQueryable | Converts a (generic) IEnumerable to a (generic) IQueryable. |
Cast | Casts the elements of a sequence to a specified type. |
OfType | Selects values, depending on their ability to be cast to a specified type. |
ToArray | Converts a collection to an array. This method forces query execution. |
ToDictionary | Puts elements into a (one-to-one) Dictionary<TKey, TValue> based on a key selector function. |
ToList | Converts a collection to a List<T>. |
ToLookup | Inserts elements into a Lookup<TKey, TElement> (a one-to-many dictionary) based on a key selector function. |
By convention, the “ToXXX” operators cause the queries to execute. The “AsXXX” operators do not. This applies to the conversion operators, but should be respected for clarity for other operators as well, including custom ones.
Operator name |
Description |
---|---|
SequenceEqual | Determines whether two sequences are equal by comparing elements in a pair-wise manner. |
Operator name |
Description |
---|---|
ElementAt | Returns the element at a specified index in a sequence. |
ElementAtOrDefault | Returns the element at a specified index in a sequence or default(T) if the index is out of range. |
First | Returns the first element of a sequence, or the first element that satisfies a condition. |
FirstOrDefault | Returns the first element of a sequence, or the first element that satisfies a condition. Returns default(T) if no such element exists. |
Last | Returns the last element of a sequence, or the last element that satisfies a condition. |
LastOrDefault | Returns the last element of a sequence, or the last element that satisfies a condition. Returns default(T) if no such element exists. |
Single | Returns the only element of a sequence, or the only element that satisfies a condition. Raises an InvalidOperationException if the sequence does not contain exactly one element. |
SingleOrDefault | Returns the only element of a sequence, or the only element that satisfies a condition. Returns default(T) if no such element exists. Raises an InvalidOperationException if the sequence contains more than one element. |
Operator name |
Description |
---|---|
DefaultIfEmpty | Replaces an empty sequence with a default valued singleton sequence. |
Empty | Returns an empty sequence. |
Range | Generates a sequence of integral numbers within a specified range. |
Repeat | Generates a sequence that contains one repeated value. |
Operator name |
Description |
---|---|
All | Determines whether all the elements in a sequence satisfy a condition. |
Any | Determines whether any elements in a sequence satisfy a condition. |
Contains | Determines whether a sequence contains a specified element. |
Operator name |
Description |
---|---|
Aggregate | Performs a custom aggregation operation on the values of a sequence. |
Average | Calculates the average value of a sequence of values. |
Count | Counts the elements in a sequence, optionally only those elements that satisfy a predicate function. |
LongCount | Counts the elements in a large sequence, optionally only those elements that satisfy a predicate function. |
Max | Determines the maximum value in a sequence. |
Min | Determines the minimum value in a sequence. |
Sum | Calculates the sum of the values in a sequence. |
In general, operators that return something other than an IEnumerable<T> will cause immediate query execution.
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