rust-bert/examples/masked_language_model_bert.rs
2021-08-20 11:08:37 +02:00

100 lines
3.5 KiB
Rust

// Copyright 2019-present, the HuggingFace Inc. team, The Google AI Language Team and Facebook, Inc.
// Copyright 2019 Guillaume Becquin
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
extern crate anyhow;
use rust_bert::bert::{
BertConfig, BertConfigResources, BertForMaskedLM, BertModelResources, BertVocabResources,
};
use rust_bert::resources::{RemoteResource, Resource};
use rust_bert::Config;
use rust_tokenizers::tokenizer::{BertTokenizer, MultiThreadedTokenizer, TruncationStrategy};
use rust_tokenizers::vocab::Vocab;
use tch::{nn, no_grad, Device, Tensor};
fn main() -> anyhow::Result<()> {
// Resources paths
let config_resource =
Resource::Remote(RemoteResource::from_pretrained(BertConfigResources::BERT));
let vocab_resource =
Resource::Remote(RemoteResource::from_pretrained(BertVocabResources::BERT));
let weights_resource =
Resource::Remote(RemoteResource::from_pretrained(BertModelResources::BERT));
let config_path = config_resource.get_local_path()?;
let vocab_path = vocab_resource.get_local_path()?;
let weights_path = weights_resource.get_local_path()?;
// Set-up masked LM model
let device = Device::Cpu;
let mut vs = nn::VarStore::new(device);
let tokenizer: BertTokenizer =
BertTokenizer::from_file(vocab_path.to_str().unwrap(), true, true)?;
let config = BertConfig::from_file(config_path);
let bert_model = BertForMaskedLM::new(&vs.root(), &config);
vs.load(weights_path)?;
// Define input
let input = [
"Looks like one [MASK] is missing",
"It was a very nice and [MASK] day",
];
let tokenized_input = tokenizer.encode_list(&input, 128, &TruncationStrategy::LongestFirst, 0);
let max_len = tokenized_input
.iter()
.map(|input| input.token_ids.len())
.max()
.unwrap();
let tokenized_input = tokenized_input
.iter()
.map(|input| input.token_ids.clone())
.map(|mut input| {
input.extend(vec![0; max_len - input.len()]);
input
})
.map(|input| Tensor::of_slice(&(input)))
.collect::<Vec<_>>();
let input_tensor = Tensor::stack(tokenized_input.as_slice(), 0).to(device);
// Forward pass
let model_output = no_grad(|| {
bert_model.forward_t(
Some(&input_tensor),
None,
None,
None,
None,
None,
None,
false,
)
});
// Print masked tokens
let index_1 = model_output
.prediction_scores
.get(0)
.get(4)
.argmax(0, false);
let index_2 = model_output
.prediction_scores
.get(1)
.get(7)
.argmax(0, false);
let word_1 = tokenizer.vocab().id_to_token(&index_1.int64_value(&[]));
let word_2 = tokenizer.vocab().id_to_token(&index_2.int64_value(&[]));
println!("{}", word_1); // Outputs "person" : "Looks like one [person] is missing"
println!("{}", word_2); // Outputs "pear" : "It was a very nice and [pleasant] day"
Ok(())
}