Creating Custom Aggregate Functions in LINQ

re: Creating Custom Aggregate Functions in LINQ

Gabe — Fri, 16 Sep 2005 01:15:17 GMT

Odds are the sum of the squares of many ints will exceed the size on an int. Is it possible to do this:

public static double SumSquares(this IEnumerable<int> source)

The LINQ Project

Paul Mooney — Fri, 16 Sep 2005 17:38:49 GMT

Now, what we're doing here with Project LINQ is that we are taking the concepts of query, step operations,...

re: Creating Custom Aggregate Functions in LINQ

Dan Miser — Sun, 18 Sep 2005 05:15:33 GMT

This doesn't appear to work with Beta 2 and the C# LINQ Preview found on PDC disc 4. If I include the "this" modifier in SumSquares, I get tons of compile errors during build. If I remove it, I get the error "System.Array does not contain a definition for SumSqaures".

I clearly remember Anders saying "this" was required, so I'm guessing it's a difference between the bits we have and you have?

re: Creating Custom Aggregate Functions in LINQ

PiersH — Mon, 19 Sep 2005 20:49:09 GMT

alternatively:

return source.Fold ((sum, x) => sum + x*x);