70 lines
1.8 KiB
AppleScript
70 lines
1.8 KiB
AppleScript
-------------- CUMULATIVE STANDARD DEVIATION -------------
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-- cumulativeStdDevns :: [Float] -> [Float]
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on cumulativeStdDevns(xs)
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script go
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on |λ|(sq, x, i)
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set {s, q} to sq
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set _s to x + s
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set _q to q + (x ^ 2)
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{{_s, _q}, ((_q / i) - ((_s / i) ^ 2)) ^ 0.5}
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end |λ|
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end script
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item 2 of mapAccumL(go, {0, 0}, xs)
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end cumulativeStdDevns
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--------------------------- TEST -------------------------
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on run
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cumulativeStdDevns({2, 4, 4, 4, 5, 5, 7, 9})
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end run
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------------------------- GENERIC ------------------------
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-- foldl :: (a -> b -> a) -> a -> [b] -> a
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on foldl(f, startValue, xs)
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tell mReturn(f)
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set v to startValue
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set lng to length of xs
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repeat with i from 1 to lng
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set v to |λ|(v, item i of xs, i, xs)
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end repeat
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return v
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end tell
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end foldl
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-- mapAccumL :: (acc -> x -> (acc, y)) -> acc -> [x] -> (acc, [y])
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on mapAccumL(f, acc, xs)
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-- 'The mapAccumL function behaves like a combination of map and foldl;
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-- it applies a function to each element of a list, passing an
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-- accumulating parameter from |Left| to |Right|, and returning a final
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-- value of this accumulator together with the new list.' (see Hoogle)
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script
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on |λ|(a, x, i)
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tell mReturn(f) to set pair to |λ|(item 1 of a, x, i)
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{item 1 of pair, (item 2 of a) & {item 2 of pair}}
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end |λ|
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end script
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foldl(result, {acc, []}, xs)
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end mapAccumL
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-- mReturn :: First-class m => (a -> b) -> m (a -> b)
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on mReturn(f)
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-- 2nd class handler function lifted into 1st class script wrapper.
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if script is class of f then
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f
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else
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script
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property |λ| : f
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end script
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end if
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end mReturn
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