如何在没有 __call__ 函数的情况下调用 torchaudio.transform.Resample？

Question

if sample_rate != sr:
        waveform = torchaudio.transforms.Resample(sample_rate, sr)(waveform)
        sample_rate = sr

我想知道这个 Resamle 是如何在那里工作的。因此，查看了 torchaudio 的文档。我以为会有 __call__ 功能。因为 Resample 被用作函数。我的意思是Resample()(waveform)。但在里面，只有 __init__ 和 forward 函数。我认为forward函数是工作函数，但我不知道为什么它被命名为'forward'而不是__call__。我错过了什么？

class Resample(torch.nn.Module):
    r"""Resample a signal from one frequency to another. A resampling method can be given.

    Args:
        orig_freq (float, optional): The original frequency of the signal. (Default: ``16000``)
        new_freq (float, optional): The desired frequency. (Default: ``16000``)
        resampling_method (str, optional): The resampling method. (Default: ``'sinc_interpolation'``)
    """

    def __init__(self,
                 orig_freq: int = 16000,
                 new_freq: int = 16000,
                 resampling_method: str = 'sinc_interpolation') -> None:
        super(Resample, self).__init__()
        self.orig_freq = orig_freq
        self.new_freq = new_freq
        self.resampling_method = resampling_method

    def forward(self, waveform: Tensor) -> Tensor:
        r"""
        Args:
            waveform (Tensor): Tensor of audio of dimension (..., time).

        Returns:
            Tensor: Output signal of dimension (..., time).
        """
        if self.resampling_method == 'sinc_interpolation':

            # pack batch
            shape = waveform.size()
            waveform = waveform.view(-1, shape[-1])

            waveform = kaldi.resample_waveform(waveform, self.orig_freq, self.new_freq)

            # unpack batch
            waveform = waveform.view(shape[:-1] + waveform.shape[-1:])

            return waveform

        raise ValueError('Invalid resampling method: %s' % (self.resampling_method))

--编辑--

我环顾了 torch.nn.module。没有定义 __call__。但只有 __call__ : Callable[..., Any] = _call_impl会这样吗？

Answer 1

下面是forward 函数在PyTorch 中如何工作的简单类似演示。

检查一下：

from typing import Callable, Any

class parent:
    def _unimplemented_forward(self, *input):
        raise NotImplementedError

    def _call_impl(self, *args):
        # original nn.Module _call_impl function contains lot more code
        # to handle exceptions, to handle hooks and for other purposes
        self.forward(*args)
    
    forward : Callable[..., Any]  = _unimplemented_forward
    __call__ : Callable[..., Any] = _call_impl

class child(parent):
    def forward(self, *args):
        print('forward function')


class child_2(parent):
    pass

运行时：

>>> c1 = child_1()
>>> c1()
forward function
>>> c2 = child_2()
>>> c2()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".\callable.py", line 8, in _call_impl
    self.forward(*args)
  File ".\callable.py", line 5, in _unimplemented_forward
    raise NotImplementedError
NotImplementedError