Multiple LINQ aggregate functions on different fields apply to the entire set?

You don't want to be iterating over the array to start with by the looks of it - you just want: var query = new { NumberOfMaleEmployees = employees. Count(x => x. Gender == "M"), NumberOfFemaleEmployees = employees.

Count(x => x. Gender == "F"), TotalSalaries = employees. Sum(x => x.

Salary), AverageSalary = employees. Average(x => x. Average), } The "latest employee" bit is slightly tricky - you basically want MaxBy from MoreLINQ which would let you write: LatestEmployee = employees.

MaxBy(x => x. DateOfring) (which you can include in the above query, of course).

You don't want to be iterating over the array to start with by the looks of it - you just want: var query = new { NumberOfMaleEmployees = employees. Count(x => x. Gender == "M"), NumberOfFemaleEmployees = employees.

Count(x => x. Gender == "F"), TotalSalaries = employees. Sum(x => x.

Salary), AverageSalary = employees. Average(x => x. Average), }; The "latest employee" bit is slightly tricky - you basically want MaxBy from MoreLINQ, which would let you write: LatestEmployee = employees.

MaxBy(x => x. DateOfring) (which you can include in the above query, of course).

Anyway I marked yours as an answer. And I am still curious if it's possible or not the way I put it in my initial question. – Iulian Sep 20 at 18:40 @Iulian: Yes, this iterates over the array 5 times.

If you don't want to do that, you'll have a hard time doing it elegantly in LINQ - it would be better to leave LINQ to one side and use dlev in that situation. Reactive Extensions can help to some extent, but it's got its own trickiness. – Jon Skeet Sep 20 at 18:46.

While Mr. Skeet's answer works, it does cause employees to be iterated 5 times (including the "latest employee". ) You're probably better off with a straight for loop that tracks each aggregation of interest: int maleCount = 0; int femaleCount = 0; long totalSalary = 0; double averageSalary = 0.0; object latestEmployee = null; for (int I = 0; I latestEmployee. ReDate) { latestEmployee = employeesi; } } femaleCount = employees.

Length - maleCount; averageSalary = totalSalary / (double)employees. Length; I've assumed that employees can be either male or female; you'd need to adjust your code if that assumption isn't warranted.

The example I used was just for the sake of making my question clearer, in my real case I have to get this results from an EF entity collection. – Iulian Sep 20 at 18:32 1 If you need to do multiple aggregations with an in-memory datasource, then you either need to use straight loops, or write your own extension method that hides the fact you're using a straight loop. From an EF data source, it's a little different, since the EF LINQ provider can generate SQL that captures the multiple aggregations.

At that point, the database can perform the aggregation as it sees fit. – dlev Sep 20 at 18:39 That makes sense.Thanks. – Iulian Sep 20 at 18:43.

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