Re: [Haskell-cafe] Mapping over multiple values of a list at once?

For example, starting from

[4,3,2,6,7]

you need to find the averages of

4,3,2 and 3,2,6 and 2,6,7

resulting in

[3,4,5]

What is the most elegant way to do that? It's probably less elegant than tails, but very likely more efficient to keep track of running sums instead of summing the sublists over and over again.

import Data.Ratio nsums n xs = map (% n) $ scanl (+) (sum (take n xs)) $ zipWith (-) (drop n xs) xs Gergely -- http://www.fastmail.fm - The professional email service