Python：函数代码速度比纯代码速度快。为什么？

Question

我在学习堆算法。 我认为堆算法作为一个函数会比纯代码慢。 所以我做了一个测试。但我发现函数代码比纯代码快得多。 我觉得这很奇怪，我不知道为什么

enter image description here

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优化得多，因此将代码放入函数中通常会使其比模块级代码运行得更快

在table of timings for common operations中，您可以看到read_local和write_local比它们的全局读/写对手更快