Python : Functional code speed is faster than pure code speed. 为什么？

Question

我正在研究堆算法。
我认为堆算法作为函数会比纯代码慢。
所以我做了一个测试。但我发现函数式代码比纯代码快得多。
我觉得这很奇怪，我不知道为什么。

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import time

def heapify(heap):
    for i in range(1, len(heap)):
        while i != 0:
            root = int((i - 1) / 2)
            if heap[i] < heap[root]:
                tmp = heap[i]
                heap[i] = heap[root]
                heap[root] = tmp
                i = root
            else:
                break
    return heap

heap = [5,2,5,0,11,12,7,8,10] * 10000

a = time.time()
for i in range(1, len(heap)):
    while i != 0:
        root = int((i - 1) / 2)
        if heap[i] < heap[root]:
            tmp = heap[i]
            heap[i] = heap[root]
            heap[root] = tmp
            i = root
        else:
            break
b = time.time()
print("func code time :", b-a)

heap2 = [5,2,5,0,11,12,7,8,10] * 10000
a = time.time()
heap2 = heapify(heap2)
b = time.time()
print("pure code time :", b-a)
print(heap == heap2)

Answer 1

在 CPython 中，局部变量查找比全局变量查找更优化，因此将代码放在函数中通常使其运行速度比模块级代码快。

在 table of timings for common operations ，您可以看到 read_local 和 write_local 比它们的全局读/写对应物更快。