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Averages/Mean time of day: Difference between revisions
Added Haskell version
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<lang groovy>println (meanTime("23:00:17", "23:40:20", "00:12:45", "00:17:19"))</lang>
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<pre>23:47:43</pre>
=={{header|Haskell}}==
<lang haskell>import Data.Complex (cis, phase)
import Data.List.Split (splitOn)
import Text.Printf (printf)
timeToRadians :: String -> Float
timeToRadians time =
let hours:minutes:seconds:_ = splitOn ":" time
s = fromIntegral (read seconds :: Int)
m = fromIntegral (read minutes :: Int)
h = fromIntegral (read hours :: Int)
in (2*pi)*(h+ (m + s/60.0 )/60.0 )/24.0
radiansToTime :: Float -> String
radiansToTime r =
let tau = pi*2
(_,fDay) = properFraction (r / tau) :: (Int, Float)
fDayPositive = if fDay < 0 then 1.0+fDay else fDay
(hours, fHours) = properFraction $ 24.0 * fDayPositive
(minutes, fMinutes) = properFraction $ 60.0 * fHours
seconds = 60.0 * fMinutes
in printf "%0d" (hours::Int) ++ ":" ++ printf "%0d" (minutes::Int) ++ ":" ++ printf "%0.0f" (seconds::Float)
meanAngle :: [Float] -> Float
meanAngle = phase . sum . map cis
main :: IO ()
main = putStrLn $ radiansToTime $ meanAngle $ map timeToRadians ["23:00:17", "23:40:20", "00:12:45", "00:17:19"]
</lang>
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<pre>23:47:43</pre>
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