getitem方法：

class MyList:

    def __init__(self):

        self.data = [10, 20, 30, 40, 50]

    def __getitem__(self, idx):

        return self.data[idx]

my_list_obj = MyList()

print(my_list_obj[2])

 

len方法：

class MyList:

    def __init__(self):

        self.data = [10, 20, 30, 40, 50]

    def __len__(self):

        return len(self.data)

my_list_obj = MyList()

print(len(my_list_obj))

 

hook函数：

import torch

import torch.nn as nn

import numpy as np

import matplotlib.pyplot as plt

torch.manual_seed(42)

np.random.seed(42)

 

张量钩子：

x = torch.tensor([2.0], requires_grad=True)

y = x ** 2

z = y ** 3

def tensor_hook(grad):

    print(f"原始梯度: {grad}")

    return grad / 2

hook_handle = y.register_hook(tensor_hook)

z.backward()

print(f"x的梯度: {x.grad}")

hook_handle.remove()@浙大疏锦行