pytorch-reader

Read PyTorch checkpoint files (.pt, .pth) without PyTorch or Burn.

The crate parses the pickle inside a checkpoint and hands back each tensor's name, element type and shape, with the bytes produced only when asked for. It reads every container torch.save has written: the ZIP archive of PyTorch 1.6 and later, the legacy pickle stream of 0.1.10 through 1.5, the TAR archive before that, and the plain pickle some tools write for configuration on its own.

use pytorch_reader::PytorchReader;

let reader = PytorchReader::new("model.pt")?;
for tensor in reader.tensors().values() {
    println!("{}: {:?} {:?}", tensor.name, tensor.dtype(), tensor.shape());
}

// Bytes are read from the file here, not at open.
let weight = reader.get("fc.weight").unwrap();
let bytes: Vec<u8> = weight.read()?;
# Ok::<(), Box<dyn std::error::Error>>(())

A checkpoint that nests its weights under a key ("state_dict", "model", ...) is opened with PytorchReader::with_top_level_key("checkpoint.pt", "state_dict"). Non-tensor values (configuration dictionaries, say) can be deserialized into any serde type with PytorchReader::load_config.

This is the reader behind burn-store, which wraps its tensors for loading into Burn modules.