for batch_idx, (batch_x, batch_y) in enumerate(test_loader)报错:can‘t pickle module objects

报错信息如下：

Traceback (most recent call last):
  File "E:/Program Files/PyCharm 2019.2/machinelearning/homework/CNN.py", line 151, in <module>
    train()
  File "E:/Program Files/PyCharm 2019.2/machinelearning/homework/CNN.py", line 140, in train
    for batch_idx, (batch_x, batch_y) in enumerate(test_loader):
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 279, in __iter__
    return _MultiProcessingDataLoaderIter(self)
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 719, in __init__
    w.start()
  File "F:\Anaconda3\lib\multiprocessing\process.py", line 112, in start
    self._popen = self._Popen(self)
  File "F:\Anaconda3\lib\multiprocessing\context.py", line 223, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "F:\Anaconda3\lib\multiprocessing\context.py", line 322, in _Popen
    return Popen(process_obj)
  File "F:\Anaconda3\lib\multiprocessing\popen_spawn_win32.py", line 89, in __init__
    reduction.dump(process_obj, to_child)
  File "F:\Anaconda3\lib\multiprocessing\reduction.py", line 60, in dump
    ForkingPickler(file, protocol).dump(obj)
TypeError: can't pickle module objects

解决办法：将

test_data = DataLoader(dataset=test, batch_size=5, shuffle=True, num_workers=2)

中num_workers=2改成等于0。num_workers代表多线程加载数据,Windows上不能用(必须0),Linux可用。继续报错：

Traceback (most recent call last):
  File "E:/Program Files/PyCharm 2019.2/machinelearning/homework/CNN.py", line 151, in <module>
    train()
  File "E:/Program Files/PyCharm 2019.2/machinelearning/homework/CNN.py", line 140, in train
    for batch_idx, (batch_x, batch_y) in enumerate(test_loader):
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 345, in __next__
    data = self._next_data()
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 385, in _next_data
    data = self._dataset_fetcher.fetch(index)  # may raise StopIteration
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\_utils\fetch.py", line 44, in fetch
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\_utils\fetch.py", line 44, in <listcomp>
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "F:\Anaconda3\lib\site-packages\torch\utils\data\dataset.py", line 207, in __getitem__
    return self.datasets[dataset_idx][sample_idx]
  File "E:/Program Files/PyCharm 2019.2/machinelearning/homework/CNN.py", line 32, in __getitem__
    img = self.transform(img)
TypeError: 'module' object is not callable

刚刚第一个问题应该是解决了的，只不过现在又出现了未知的错误。

---

错误已经解决：加载测试数据和加载训练数据的transform不一样！！！