PyTorch中如何保存已加载权重的完整模型？

Hey there! Let's clear this up for you right away—your current workflow actually does exactly what you want!

Here's why:

1. You first instantiate your model with lin_model = ModelClass(args)
2. Then you load the pre-trained weights into this model using lin_model.load_state_dict(torch.load('state_dict.pt'))—this step replaces all the initial random weights in lin_model with the weights from your state_dict.pt file.
3. When you run torch.save(lin_model, PATH) afterward, you're saving the entire model instance, including the already-loaded weights as a .pt file. This is exactly the full, weight-loaded model you were aiming for.

To double-check that the saved model has the correct weights, you can load it back and compare parameters with the original model:

# Load the saved full model
loaded_full_model = torch.load(PATH)

# Compare a parameter (e.g., the weight of a fully connected layer)
# This should return True if weights match exactly
print(torch.allclose(lin_model.fc.weight, loaded_full_model.fc.weight))

Just to clarify the difference between the two saving approaches you mentioned:

• Saving only the state_dict: torch.save(model.state_dict(), 'state_dict.pt') saves just the model's parameter weights, not the model structure itself. To use this, you need to re-instantiate the model class first, then load the state_dict.
• Saving the full model: torch.save(model, PATH) saves both the model structure and its weights. Loading it is as simple as torch.load(PATH)—though you need to make sure the ModelClass definition is accessible in the environment where you load it (otherwise you'll get an error).

While your method works great for quick experiments or personal use, in production settings, saving just the state_dict is usually preferred. It's smaller in file size, more flexible (you can easily load it into different model instances if needed), and less prone to environment-related loading issues. But for your current use case, your approach is totally valid.

内容的提问来源于stack exchange，提问作者Tarun Narayanan