Data commit

Task/Sleeping-Beauty-problem/Python/sleeping-beauty-problem-1.py

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+from random import choice
+
+def sleeping_beauty_experiment(repetitions):
+    """
+    Run the Sleeping Beauty Problem experiment `repetitions` times, checking to see
+    how often we had heads on waking Sleeping Beauty.
+    """
+    gotheadsonwaking = 0
+    wakenings = 0
+    for _ in range(repetitions):
+        coin_result = choice(["heads", "tails"])
+
+        # On Monday, we check if we got heads.
+        wakenings += 1
+        if coin_result == "heads":
+            gotheadsonwaking += 1
+
+        # If tails, we do this again, but of course we will not add as if it was heads..
+        if coin_result == "tails":
+            wakenings += 1
+            if coin_result == "heads":
+                gotheadsonwaking += 1   # never done
+
+
+    # Show the number of times she was wakened.
+    print("Wakenings over", repetitions, "experiments:", wakenings)
+
+    # Return the number of correct bets SB made out of the total number
+    # of times she is awoken over all the experiments with that bet.
+    return gotheadsonwaking / wakenings
+
+
+CREDENCE = sleeping_beauty_experiment(1_000_000)
+print("Results of experiment:  Sleeping Beauty should estimate a credence of:", CREDENCE)

Task/Sleeping-Beauty-problem/Python/sleeping-beauty-problem-2.py

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+'''Sleeping Beauty Problem'''
+
+from random import choice
+from itertools import repeat
+from functools import reduce
+
+
+# experiment :: (Int, Int) -> IO (Int, Int)
+def experiment(headsWakings):
+    '''A pair of counts updated by a coin flip.
+    '''
+    heads, wakings = headsWakings
+
+    return (
+        1 + heads, 1 + wakings
+    ) if "h" == choice(["h", "t"]) else (
+        heads, 2 + wakings
+    )
+
+
+# ------------------------- TEST -------------------------
+# main :: IO ()
+def main():
+    '''Observed results from one million runs.'''
+
+    n = 1_000_000
+    heads, wakes = applyN(n)(
+        experiment
+    )(
+        (0, 0)
+    )
+
+    print(
+        f'{wakes} wakenings over {n} experiments.\n'
+    )
+    print('Sleeping Beauty should estimate credence')
+    print(f'at around {round(heads/wakes, 3)}')
+
+
+# ----------------------- GENERIC ------------------------
+
+# applyN :: Int -> (a -> a) -> a -> a
+def applyN(n):
+    '''n applications of f.
+       (Church numeral n).
+    '''
+    def go(f):
+        def ga(a, g):
+            return g(a)
+
+        def fn(x):
+            return reduce(ga, repeat(f, n), x)
+        return fn
+    return go
+
+
+# MAIN ---
+if __name__ == '__main__':
+    main()