transformers/examples/translation/t5/README.md
Patrick von Platen 80a1694514
[Examples, T5] Change newstest2013 to newstest2014 and clean up (#3817)
* Refactored use of newstest2013 to newstest2014. Fixed bug where argparse consumed first command line argument as model_size argument rather than using default model_size by forcing explicit --model_size flag inclusion

* More pythonic file handling through 'with' context

* COSMETIC - ran Black and isort

* Fixed reference to number of lines in newstest2014

* Fixed failing test. More pythonic file handling

* finish PR from tholiao

* remove outcommented lines

* make style

* make isort happy

Co-authored-by: Thomas Liao <tholiao@gmail.com>
2020-04-16 20:00:41 +02:00

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***This script evaluates the multitask pre-trained checkpoint for ``t5-base`` (see paper [here](https://arxiv.org/pdf/1910.10683.pdf)) on the English to German WMT dataset. Please note that the results in the paper were attained using a model fine-tuned on translation, so that results will be worse here by approx. 1.5 BLEU points***
### Intro
This example shows how T5 (here the official [paper](https://arxiv.org/abs/1910.10683)) can be
evaluated on the WMT English-German dataset.
### Get the WMT Data
To be able to reproduce the authors' results on WMT English to German, you first need to download
the WMT14 en-de news datasets.
Go on Stanford's official NLP [website](https://nlp.stanford.edu/projects/nmt/) and find "newstest2014.en" and "newstest2014.de" under WMT'14 English-German data or download the dataset directly via:
```bash
curl https://nlp.stanford.edu/projects/nmt/data/wmt14.en-de/newstest2014.en > newstest2014.en
curl https://nlp.stanford.edu/projects/nmt/data/wmt14.en-de/newstest2014.de > newstest2014.de
```
You should have 2737 sentences in each file. You can verify this by running:
```bash
wc -l newstest2014.en # should give 2737
```
### Usage
Let's check the longest and shortest sentence in our file to find reasonable decoding hyperparameters:
Get the longest and shortest sentence:
```bash
awk '{print NF}' newstest2014.en | sort -n | head -1 # shortest sentence has 2 word
awk '{print NF}' newstest2014.en | sort -n | tail -1 # longest sentence has 91 words
```
We will set our `max_length` to ~3 times the longest sentence and leave `min_length` to its default value of 0.
We decode with beam search `num_beams=4` as proposed in the paper. Also as is common in beam search we set `early_stopping=True` and `length_penalty=2.0`.
To create translation for each in dataset and get a final BLEU score, run:
```bash
python evaluate_wmt.py <path_to_newstest2014.en> newstest2014_de_translations.txt <path_to_newstest2014.de> newsstest2014_en_de_bleu.txt
```
the default batch size, 16, fits in 16GB GPU memory, but may need to be adjusted to fit your system.
### Where is the code?
The core model is in `src/transformers/modeling_t5.py`. This directory only contains examples.
### BLEU Scores
The BLEU score is calculated using [sacrebleu](https://github.com/mjpost/sacreBLEU) by mjpost.
To get the BLEU score we used