Add a save function to Data and HeteroData

[skyelves]

Currently I am working on implementing GNN models. Sometimes after training a few epochs, I want to stop training, and save the model and the graph. I can save the model with torch.save(model.state_dict(), PATH). However, I didn't find a way to for me to save the data like torch.save. Though I can save it in a csv file, it may be much better if there is a built-in function in Data class and HeteroData class such as save(dir/filename) . Also a complementary function load(dir/filename).

[rusty1s]

You can also save the data via torch.save(data, ...) and load it via torch.load. Note that this is already automatically handled when using our Dataset and InMemoryDataset abstractions.

[skyelves]

Yeah it works, thanks for answering!