# BERT微调

### Model Architecture

* Predict `intent` and `slot` at the same time from **one BERT model** (=Joint model)
* total\_loss = intent\_loss + coef \* slot\_loss (Change coef with `--slot_loss_coef` option)
* **If you want to use CRF layer, give `--use_crf` option**

### Dependencies

* python>=3.6
* torch==1.6.0
* transformers==3.0.2
* seqeval==0.0.12
* pytorch-crf==0.7.2

### Dataset

|       | Train  | Dev | Test | Intent Labels | Slot Labels |
| ----- | ------ | --- | ---- | ------------- | ----------- |
| ATIS  | 4,478  | 500 | 893  | 21            | 120         |
| Snips | 13,084 | 700 | 700  | 7             | 72          |

* The number of labels are based on the *train* dataset.
* Add `UNK` for labels (For intent and slot labels which are only shown in *dev* and *test* dataset)
* Add `PAD` for slot label

### Training & Evaluation

```bash
$ python3 main.py --task {task_name} \
                  --model_type {model_type} \
                  --model_dir {model_dir_name} \
                  --do_train --do_eval \
                  --use_crf

# For ATIS
$ python3 main.py --task atis \
                  --model_type bert \
                  --model_dir atis_model \
                  --do_train --do_eval
# For Snips
$ python3 main.py --task snips \
                  --model_type bert \
                  --model_dir snips_model \
                  --do_train --do_eval

# python JointBERT/main.py --task atis --model_type bert --model_dir experiments/jointbert_0 --do_train --do_eval --train_batch_size 2
```

### Prediction

```bash
$ python3 predict.py --input_file {INPUT_FILE_PATH} --output_file {OUTPUT_FILE_PATH} --model_dir {SAVED_CKPT_PATH}
```

### Results

* Run 5 \~ 10 epochs (Record the best result)
* Only test with `uncased` model
* ALBERT xxlarge sometimes can't converge well for slot prediction.

|           |              | Intent acc (%) | Slot F1 (%) | Sentence acc (%) |
| --------- | ------------ | -------------- | ----------- | ---------------- |
| **Snips** | BERT         | **99.14**      | 96.90       | 93.00            |
|           | BERT + CRF   | 98.57          | **97.24**   | **93.57**        |
|           | ALBERT + CRF | 99.00          | 96.55       | 92.57            |
| **ATIS**  | BERT         | 97.87          | 95.59       | 88.24            |
|           | BERT + CRF   | **97.98**      | 95.93       | 88.58            |


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