[Haskell-cafe] Help to create a function to calculate a n element moving average ??

[Richard O'Keefe]

On 27/09/2010, at 5:20 AM, rgowka1 wrote:

> Type signature would be Int -> [Double] -> [(Double,Double)]
> 
> Any thoughts or ideas on how to calculate a n-element moving average
> of a list of Doubles?
> 
> Let's say [1..10]::[Double]
> 
> what is the function to calculate the average of the 3 elements?
> 
> [(1,0),(2,0),(3,2),(4,3)....] :: [(Double,Double)]

> moving_average3 (xs0 @ (_ : (xs1 @ (_ : xs2)))) =
>   zipWith3 (\x y z -> (x+y+z)/3) xs0 xs1 xs2

*Main> moving_average3 [1..10]
[2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0]

The result is two elements shorter than the original, but that
_is_ the definition of moving average after all.