nbytes和getsizeof返回不同的值 [英] nbytes and getsizeof return different values

问题描述

我注意到，当将库存入NumPy数组时，nbytes和getsizeof返回两个不同的值.

I have noticed that nbytes and getsizeof returns two different values when the bank to a NumPy array.

示例:

import sys
import numpy as np
x = np.random.rand(10000, 50)
print('x.nbytes: {0} bytes'.format(x.nbytes))
print('sys.getsizeof(x): {0} bytes'.format(sys.getsizeof(x)))

输出:

x.nbytes: 4000000 bytes
sys.getsizeof(x): 4000112 bytes

为什么?

推荐答案

这是因为nbytes仅返回存储数据的大小，而sys.getsizeof返回整个对象的大小，即存储的数据的大小加上一些开销. numpy数组的开销很小，因为它们必须存储数组尺寸，数据类型和类似信息.

This is because nbytes only returns the size of stored data, while sys.getsizeof returns the size of the whole object, i.e. the size of the stored data plus some overhead. There is a small overhead for numpy arrays, because they have to store the array dimensions, the datatype and similar information.

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