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# Text classification examples

## PyTorch version

Based on the script [`run_glue.py`](https://github.com/huggingface/transformers/blob/master/examples/text-classification/run_glue.py).

Fine-tuning the library models for sequence classification on the GLUE benchmark: [General Language Understanding
Evaluation](https://gluebenchmark.com/). This script can fine-tune any of the models on the [hub](https://huggingface.co/models)
and can also be used for your own data in a csv or a JSON file (the script might need some tweaks in that case, refer
to the comments inside for help).

GLUE is made up of a total of 9 different tasks. Here is how to run the script on one of them:

```bash
export TASK_NAME=mrpc

python run_glue.py \
  --model_name_or_path bert-base-cased \
  --task_name $TASK_NAME \
  --do_train \
  --do_eval \
  --max_seq_length 128 \
  --per_device_train_batch_size 32 \
  --learning_rate 2e-5 \
  --num_train_epochs 3 \
  --output_dir /tmp/$TASK_NAME/
```

where task name can be one of cola, sst2, mrpc, stsb, qqp, mnli, qnli, rte, wnli.

We get the following results on the dev set of the benchmark with the previous commands (with an exception for MRPC and
WNLI which are tiny and where we used 5 epochs isntead of 3). Trainings are seeded so you should obtain the same
results with PyTorch 1.6.0 (and close results with different versions), training times are given for information (a
single Titan RTX was used):

| Task  | Metric                       | Result      | Training time |
|-------|------------------------------|-------------|---------------|
| CoLA  | Matthew's corr               | 56.53       | 3:17          |
| SST-2 | Accuracy                     | 92.32       | 26:06         |
| MRPC  | F1/Accuracy                  | 88.85/84.07 | 2:21          |
| STS-B | Person/Spearman corr.        | 88.64/88.48 | 2:13          |
| QQP   | Accuracy/F1                  | 90.71/87.49 | 2:22:26       |
| MNLI  | Matched acc./Mismatched acc. | 83.91/84.10 | 2:35:23       |
| QNLI  | Accuracy                     | 90.66       | 40:57         |
| RTE   | Accuracy                     | 65.70       | 57            |
| WNLI  | Accuracy                     | 56.34       | 24            |

Some of these results are significantly different from the ones reported on the test set of GLUE benchmark on the
website. For QQP and WNLI, please refer to [FAQ #12](https://gluebenchmark.com/faq) on the website.

### Mixed precision training

If you have a GPU with mixed precision capabilities (architecture Pascal or more recent), you can use mixed precision
training with PyTorch 1.6.0 or latest, or by installing the [Apex](https://github.com/NVIDIA/apex) library for previous
versions. Just add the flag `--fp16` to your command launching one of the scripts mentioned above!

Using mixed precision training usually results in 2x-speedup for training with the same final results:

| Task  | Metric                       | Result      | Training time | Result (FP16) | Training time (FP16) |
|-------|------------------------------|-------------|---------------|---------------|----------------------|
| CoLA  | Matthew's corr               | 56.53       | 3:17          | 56.78         | 1:41                 |
| SST-2 | Accuracy                     | 92.32       | 26:06         | 91.74         | 13:11                |
| MRPC  | F1/Accuracy                  | 88.85/84.07 | 2:21          | 88.12/83.58   | 1:10                 |
| STS-B | Person/Spearman corr.        | 88.64/88.48 | 2:13          | 88.71/88.55   | 1:08                 |
| QQP   | Accuracy/F1                  | 90.71/87.49 | 2:22:26       | 90.67/87.43   | 1:11:54              |
| MNLI  | Matched acc./Mismatched acc. | 83.91/84.10 | 2:35:23       | 84.04/84.06   | 1:17:06              |
| QNLI  | Accuracy                     | 90.66       | 40:57         | 90.96         | 20:16                |
| RTE   | Accuracy                     | 65.70       | 57            | 65.34         | 29                   |
| WNLI  | Accuracy                     | 56.34       | 24            | 56.34         | 12                   |


# Run TensorFlow 2.0 version

Based on the script [`run_tf_glue.py`](https://github.com/huggingface/transformers/blob/master/examples/text-classification/run_tf_glue.py).

Fine-tuning the library TensorFlow 2.0 Bert model for sequence classification on the  MRPC task of the GLUE benchmark: [General Language Understanding Evaluation](https://gluebenchmark.com/).

This script has an option for mixed precision (Automatic Mixed Precision / AMP) to run models on Tensor Cores (NVIDIA Volta/Turing GPUs) and future hardware and an option for XLA, which uses the XLA compiler to reduce model runtime.
Options are toggled using `USE_XLA` or `USE_AMP` variables in the script.
These options and the below benchmark are provided by @tlkh.

Quick benchmarks from the script (no other modifications):

| GPU    | Mode | Time (2nd epoch) | Val Acc (3 runs) |
| --------- | -------- | ----------------------- | ----------------------|
| Titan V | FP32 | 41s | 0.8438/0.8281/0.8333 |
| Titan V | AMP | 26s | 0.8281/0.8568/0.8411 |
| V100    | FP32 | 35s | 0.8646/0.8359/0.8464 |
| V100    | AMP | 22s | 0.8646/0.8385/0.8411 |
| 1080 Ti | FP32 | 55s | - |

Mixed precision (AMP) reduces the training time considerably for the same hardware and hyper-parameters (same batch size was used).


## Run generic text classification script in TensorFlow

The script [run_tf_text_classification.py](https://github.com/huggingface/transformers/blob/master/examples/text-classification/run_tf_text_classification.py) allows users to run a text classification on their own CSV files. For now there are few restrictions, the CSV files must have a header corresponding to the column names and not more than three columns: one column for the id, one column for the text and another column for a second piece of text in case of an entailment classification for example.

To use the script, one as to run the following command line:
```bash
python run_tf_text_classification.py \
  --train_file train.csv \ ### training dataset file location (mandatory if running with --do_train option)
  --dev_file dev.csv \ ### development dataset file location (mandatory if running with --do_eval option)
  --test_file test.csv \ ### test dataset file location (mandatory if running with --do_predict option)
  --label_column_id 0 \ ### which column corresponds to the labels
  --model_name_or_path bert-base-multilingual-uncased \
  --output_dir model \
  --num_train_epochs 4 \
  --per_device_train_batch_size 16 \
  --per_device_eval_batch_size 32 \
  --do_train \
  --do_eval \
  --do_predict \
  --logging_steps 10 \
  --evaluation_strategy steps \
  --save_steps 10 \
  --overwrite_output_dir \
  --max_seq_length 128
```


## XNLI

Based on the script [`run_xnli.py`](https://github.com/huggingface/transformers/blob/master/examples/text-classification/run_xnli.py).

[XNLI](https://www.nyu.edu/projects/bowman/xnli/) is a crowd-sourced dataset based on [MultiNLI](http://www.nyu.edu/projects/bowman/multinli/). It is an evaluation benchmark for cross-lingual text representations. Pairs of text are labeled with textual entailment annotations for 15 different languages (including both high-resource language such as English and low-resource languages such as Swahili).

#### Fine-tuning on XNLI

This example code fine-tunes mBERT (multi-lingual BERT) on the XNLI dataset. It runs in 106 mins on a single tesla V100 16GB.

```bash
python run_xnli.py \
  --model_name_or_path bert-base-multilingual-cased \
  --language de \
  --train_language en \
  --do_train \
  --do_eval \
  --per_device_train_batch_size 32 \
  --learning_rate 5e-5 \
  --num_train_epochs 2.0 \
  --max_seq_length 128 \
  --output_dir /tmp/debug_xnli/ \
  --save_steps -1
```

Training with the previously defined hyper-parameters yields the following results on the **test** set:

```bash
acc = 0.7093812375249501
```
