Pytorch: IsADirectoryError: [Errno 21]

Question

Could someone please explain to me why this function:

def train_graph_classifier(model_name, **model_kwargs):
  pl.seed_everything(42)

  # Create a PyTorch Lightning trainer with the generation callback
  root_dir = os.path.join('/home/predictor2', "GraphLevel" + model_name)
  os.makedirs(root_dir, exist_ok=True)
  trainer = pl.Trainer(default_root_dir=root_dir,
                     callbacks=[ModelCheckpoint(save_weights_only=True, mode="max", monitor="val_acc")],
                     gpus=1 if str(device).startswith("cuda") else 0,
                     max_epochs=500,
                     progress_bar_refresh_rate=0)
  trainer.logger._default_hp_metric = None # Optional logging argument that we don't need

  # Check whether pretrained model exists. If yes, load it and skip training
  pretrained_filename = os.path.join('/home/predictor2', f"GraphLevel{model_name}.ckpt")
  if os.path.isfile(pretrained_filename):
    print("Found pretrained model, loading...")
    model = GraphLevelGNN.load_from_checkpoint(pretrained_filename)
  else:
    pl.seed_everything(42)
    model = GraphLevelGNN(c_in=dataset.num_node_features, 
                          c_out=1 if dataset.num_classes==2 else dataset.num_classes,  #change
                          **model_kwargs)
    trainer.fit(model, graph_train_loader, graph_val_loader)
    model = GraphLevelGNN.load_from_checkpoint(trainer.checkpoint_callback.best_model_path)

  # Test best model on validation and test set
  train_result = trainer.test(model, graph_train_loader, verbose=False)
  test_result = trainer.test(model, graph_test_loader, verbose=False)
  result = {"test": test_result[0]['test_acc'], "train": train_result[0]['test_acc']} 
  return model, result

Returns the error:

Traceback (most recent call last):
  File "stability_v3_alternative_net.py", line 604, in <module>
    dp_rate=0.2)
  File "stability_v3_alternative_net.py", line 591, in train_graph_classifier
    model = GraphLevelGNN.load_from_checkpoint(trainer.checkpoint_callback.best_model_path)
  File "/root/miniconda3/lib/python3.7/site-packages/pytorch_lightning/core/saving.py", line 139, in load_from_checkpoint
    checkpoint = pl_load(checkpoint_path, map_location=lambda storage, loc: storage)
  File "/root/miniconda3/lib/python3.7/site-packages/pytorch_lightning/utilities/cloud_io.py", line 46, in load
    with fs.open(path_or_url, "rb") as f:
  File "/root/miniconda3/lib/python3.7/site-packages/fsspec/spec.py", line 1043, in open
    **kwargs,
  File "/root/miniconda3/lib/python3.7/site-packages/fsspec/implementations/local.py", line 159, in _open
    return LocalFileOpener(path, mode, fs=self, **kwargs)
  File "/root/miniconda3/lib/python3.7/site-packages/fsspec/implementations/local.py", line 254, in __init__
    self._open()
  File "/root/miniconda3/lib/python3.7/site-packages/fsspec/implementations/local.py", line 259, in _open
    self.f = open(self.path, mode=self.mode)
IsADirectoryError: [Errno 21] Is a directory: '/home/predictor'

where /home/predictor is the current directory i'm working in? (I made predictor2 directory because I get the same error when I replace predictor2 with predictor in the above code).

I understand that it's telling me that it's trying to write a file or something but it's finding that the location in a directory, I can get that from seeing other people's answers. But I can't see specifically here what the issue is becaues I don't name my working directory anywhere? The code was taken from this example.

Answer 1

This:

model=GraphLevelGNN.load_from_checkpoint(trainer.checkpoint_callback.best_model_path)

is failing because you are trying to open a directory and not a file. Check that trainer.checkpoint_callback.best_model_path actually is the path to your .ckpt . As it looks like it is not, then you need to figure out why your callback isn't storing the right path. You can of course hardcode it yourself for an ugly solution.