ok wrote:
There are a number of interesting issues raised by mbeddoe's Math.Statistics.
data (Floating a, Ord a) => Simple_Continuous_Variate a = SCV [a] Int a a (Array Int a)
list_to_variate xs = SCV xs n m s o where n = length xs m = sum xs / fromIntegral n s = sum [(x - m)^2 | x <- xs] / fromIntegral (n - 1) o = listArray (1,n) (sort xs)
vLength (SCV _ n _ _ _) = n vMean (SCV _ _ m _ _) = m vSd (SCV _ _ _ s _) = s vMin (SCV _ _ _ _ a) = a ! 1 vMax (SCV _ n _ _ a) = a ! n vRange scv = vMax scv - vMin scv vMedian (SCV _ n _ _ a) | odd n = a ! ((n+1)`div`2) | even n = ((a ! l) + (a ! u))/2 where l = n `div` 2 u = n - l .....
Math.Statistics eats many good names. I would also suggest offering a type class interface. Then you could operate on various containers besides a list: -- A class for extracting a summary number from a type. -- None of these make much sense without Ord. -- I could imagine using (+) and `div` so why require (/)? class (Ord b) => SingleStat a b | a -> b where samples :: a -> Integer -- lump in with SingleStat mean :: a -> b var :: a -> b stddev :: a -> b moment :: Int -> a -> b range :: a -> b min :: a -> b max :: a -> b median :: a -> b instance SingleStat [Integer] Integer where ... instance SingleStat [Double] Double where ... instance (Ix i) => SingleStat (Array i Double) Double where ... instance SingleStat (Simple_Continuous_Variate a) where ... -- And then I could make interesting things like Histogram, -- where the data is Int's but the statistics are Doubles: newtype Histogram = Histogram (Map Int Int) instance SingleStat Histogram Double where ... Cheers, Chris