checkpoint_dir is a required argument

[sai8951]

In the __init__() of class UNetTrainer, checkpoint_dir is out of kwargs.

pytorch-3dunet/pytorch3dunet/unet3d/trainer.py

Lines 89 to 92 in 5917023

	def __init__(self, model, optimizer, lr_scheduler, loss_criterion, eval_criterion, loaders, checkpoint_dir,
	max_num_epochs, max_num_iterations, validate_after_iters=200, log_after_iters=100, validate_iters=None,
	num_iterations=1, num_epoch=0, eval_score_higher_is_better=True, tensorboard_formatter=None,
	skip_train_validation=False, resume=None, pre_trained=None, **kwargs):

The code always runs L145 if block; if 'checkpoint_dir' not in kwargs:.

pytorch-3dunet/pytorch3dunet/unet3d/trainer.py

Lines 145 to 146 in 5917023

	if 'checkpoint_dir' not in kwargs:
	self.checkpoint_dir = os.path.split(pre_trained)[0]

It causes unintended overwrite of checkpoint file.
The if sentence should be if not self.checkpoint_dir: or the if block should be removed.

[wolny]

Hi @sai8951, thanks for the PR. You're absolutely right!