updated from Atlas

attic/decorators/fibonacci.py

@@ -0,0 +1,60 @@
+
+# source: http://oeis.org/A000045
+fibo_seq = [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610,
+            987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025,
+            121393, 196418, 317811, 514229, 832040, 1346269, 2178309,
+            3524578, 5702887, 9227465, 14930352, 24157817, 39088169]
+
+from functools import lru_cache
+
+def fibonacci(n):
+    if n < 2:
+        return n
+    return fibonacci(n-2) + fibonacci(n-1)
+
+@lru_cache()
+def fibonacci2(n):
+    if n < 2:
+        return n
+    return fibonacci2(n-2) + fibonacci2(n-1)
+
+def memoize(func):
+    '''simplest memoizing decorator'''
+    cache = {}
+    def memoized(*args):
+        if args not in cache:
+            cache[args] = func(*args)
+        return cache[args]
+    return memoized
+
+def test():
+    for i, expected in enumerate(fibo_seq[:31]):
+        print(i, expected)
+        assert fibonacci(i) == expected
+
+def chronograph():
+    global fibonacci
+    from time import time
+    t0 = time()
+    n = 32
+    res = fibonacci(n)
+    #res = [fibonacci(n) for n in range(30)]
+    t1 = time()
+    print(n, res, format(t1-t0, '0.6f'))
+
+    t0 = time()
+    res = fibonacci2(n)
+    #res = [fibonacci2(n) for n in range(30)]
+    t1 = time()
+    print(n, res, format(t1-t0, '0.6f'))
+
+    t0 = time()
+    fibonacci = memoize(fibonacci)
+    res = fibonacci(n)
+    #res = [fibonacci2(n) for n in range(30)]
+    t1 = time()
+    print(n, res, format(t1-t0, '0.6f'))
+
+if __name__=='__main__':
+    #test()
+    chronograph()