Module gpt2

GPT2 (Radford et al.)

Implementation of the GPT2 language model (Language Models are Unsupervised Multitask Learners Radford, Wu, Child, Luan, Amodei, Sutskever 2019). The base model is implemented in the gpt2_model::Gpt2Model struct. The model also includes a language model head: gpt2_model::GPT2LMHeadModel implementing the common generation_utils::LanguageGenerator trait shared between the models used for generation (see pipelines for more information).

Model set-up and pre-trained weights loading

A full working example is provided in examples/generation_gpt2, run with cargo run --example generation_gpt2. All models expect the following resources:

• Configuration file expected to have a structure following the Transformers library
• Model weights are expected to have a structure and parameter names following the Transformers library. A conversion using the Python utility scripts is required to convert the .bin weights to the .ot format.
• Gpt2Tokenizer using a vocab.txt vocabulary and merges.txt 2-gram merges

Pretrained models are available and can be downloaded using RemoteResources.

use tch::{nn, Device};
use rust_bert::gpt2::{GPT2LMHeadModel, Gpt2Config};
use rust_bert::resources::{LocalResource, ResourceProvider};
use rust_bert::Config;
use rust_tokenizers::tokenizer::Gpt2Tokenizer;

let config_resource = LocalResource {
    local_path: PathBuf::from("path/to/config.json"),
};
let vocab_resource = LocalResource {
    local_path: PathBuf::from("path/to/vocab.txt"),
};
let merges_resource = LocalResource {
    local_path: PathBuf::from("path/to/vocab.txt"),
};
let weights_resource = LocalResource {
    local_path: PathBuf::from("path/to/model.ot"),
};
let config_path = config_resource.get_local_path()?;
let vocab_path = vocab_resource.get_local_path()?;
let merges_path = merges_resource.get_local_path()?;
let weights_path = weights_resource.get_local_path()?;

let device = Device::cuda_if_available();
let mut vs = nn::VarStore::new(device);
let tokenizer: Gpt2Tokenizer = Gpt2Tokenizer::from_file(
    vocab_path.to_str().unwrap(),
    merges_path.to_str().unwrap(),
    true,
)?;
let config = Gpt2Config::from_file(config_path);
let gpt2_model = GPT2LMHeadModel::new(&vs.root(), &config);
vs.load(weights_path)?;

Structs

GPT2Generator

Language generation model based on the GPT2 architecture

GPT2LMHeadModel

GPT2 Language Modeling head

Gpt2Config

GPT2 model configuration

Gpt2ConfigResources

GPT2 Pretrained model config files

Gpt2MergesResources

GPT2 Pretrained model merges files

Gpt2Model

GPT2 Base model

Gpt2ModelOutput

Container for the GPT2 model output.

Gpt2ModelResources

GPT2 Pretrained model weight files

Gpt2VocabResources

GPT2 Pretrained model vocab files