Reorganize examples (#9010)

* Reorganize example folder

* Continue reorganization

* Change requirements for tests

* Final cleanup

* Finish regroup with tests all passing

* Copyright

* Requirements and readme

* Make a full link for the documentation

* Address review comments

* Apply suggestions from code review
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Add symlink

* Reorg again

* Apply suggestions from code review
Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

* Adapt title

* Update to new strucutre

* Remove test

* Update READMEs
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

examples/legacy/token-classification/README.md

+## Token classification
+
+Based on the scripts [`run_ner.py`](https://github.com/huggingface/transformers/blob/master/examples/contrib/legacy/token-classification/run_ner.py).
+
+The following examples are covered in this section:
+
+* NER on the GermEval 2014 (German NER) dataset
+* Emerging and Rare Entities task: WNUT’17 (English NER) dataset
+
+Details and results for the fine-tuning provided by @stefan-it.
+
+### GermEval 2014 (German NER) dataset
+
+#### Data (Download and pre-processing steps)
+
+Data can be obtained from the [GermEval 2014](https://sites.google.com/site/germeval2014ner/data) shared task page.
+
+Here are the commands for downloading and pre-processing train, dev and test datasets. The original data format has four (tab-separated) columns, in a pre-processing step only the two relevant columns (token and outer span NER annotation) are extracted:
+
+```bash
+curl -L 'https://drive.google.com/uc?export=download&id=1Jjhbal535VVz2ap4v4r_rN1UEHTdLK5P' \
+| grep -v "^#" | cut -f 2,3 | tr '\t' ' ' > train.txt.tmp
+curl -L 'https://drive.google.com/uc?export=download&id=1ZfRcQThdtAR5PPRjIDtrVP7BtXSCUBbm' \
+| grep -v "^#" | cut -f 2,3 | tr '\t' ' ' > dev.txt.tmp
+curl -L 'https://drive.google.com/uc?export=download&id=1u9mb7kNJHWQCWyweMDRMuTFoOHOfeBTH' \
+| grep -v "^#" | cut -f 2,3 | tr '\t' ' ' > test.txt.tmp
+```
+
+The GermEval 2014 dataset contains some strange "control character" tokens like `'\x96', '\u200e', '\x95', '\xad' or '\x80'`.
+One problem with these tokens is, that `BertTokenizer` returns an empty token for them, resulting in misaligned `InputExample`s.
+The `preprocess.py` script located in the `scripts` folder a) filters these tokens and b) splits longer sentences into smaller ones (once the max. subtoken length is reached).
+
+Let's define some variables that we need for further pre-processing steps and training the model:
+
+```bash
+export MAX_LENGTH=128
+export BERT_MODEL=bert-base-multilingual-cased
+```
+
+Run the pre-processing script on training, dev and test datasets:
+
+```bash
+python3 scripts/preprocess.py train.txt.tmp $BERT_MODEL $MAX_LENGTH > train.txt
+python3 scripts/preprocess.py dev.txt.tmp $BERT_MODEL $MAX_LENGTH > dev.txt
+python3 scripts/preprocess.py test.txt.tmp $BERT_MODEL $MAX_LENGTH > test.txt
+```
+
+The GermEval 2014 dataset has much more labels than CoNLL-2002/2003 datasets, so an own set of labels must be used:
+
+```bash
+cat train.txt dev.txt test.txt | cut -d " " -f 2 | grep -v "^$"| sort | uniq > labels.txt
+```
+
+#### Prepare the run
+
+Additional environment variables must be set:
+
+```bash
+export OUTPUT_DIR=germeval-model
+export BATCH_SIZE=32
+export NUM_EPOCHS=3
+export SAVE_STEPS=750
+export SEED=1
+```
+
+#### Run the Pytorch version
+
+To start training, just run:
+
+```bash
+python3 run_ner.py --data_dir ./ \
+--labels ./labels.txt \
+--model_name_or_path $BERT_MODEL \
+--output_dir $OUTPUT_DIR \
+--max_seq_length  $MAX_LENGTH \
+--num_train_epochs $NUM_EPOCHS \
+--per_device_train_batch_size $BATCH_SIZE \
+--save_steps $SAVE_STEPS \
+--seed $SEED \
+--do_train \
+--do_eval \
+--do_predict
+```
+
+If your GPU supports half-precision training, just add the `--fp16` flag. After training, the model will be both evaluated on development and test datasets.
+
+#### JSON-based configuration file
+
+Instead of passing all parameters via commandline arguments, the `run_ner.py` script also supports reading parameters from a json-based configuration file:
+
+```json
+{
+    "data_dir": ".",
+    "labels": "./labels.txt",
+    "model_name_or_path": "bert-base-multilingual-cased",
+    "output_dir": "germeval-model",
+    "max_seq_length": 128,
+    "num_train_epochs": 3,
+    "per_device_train_batch_size": 32,
+    "save_steps": 750,
+    "seed": 1,
+    "do_train": true,
+    "do_eval": true,
+    "do_predict": true
+}
+```
+
+It must be saved with a `.json` extension and can be used by running `python3 run_ner.py config.json`.
+
+#### Evaluation
+
+Evaluation on development dataset outputs the following for our example:
+
+```bash
+10/04/2019 00:42:06 - INFO - __main__ -   ***** Eval results  *****
+10/04/2019 00:42:06 - INFO - __main__ -     f1 = 0.8623348017621146
+10/04/2019 00:42:06 - INFO - __main__ -     loss = 0.07183869666975543
+10/04/2019 00:42:06 - INFO - __main__ -     precision = 0.8467916366258111
+10/04/2019 00:42:06 - INFO - __main__ -     recall = 0.8784592370979806
+```
+
+On the test dataset the following results could be achieved:
+
+```bash
+10/04/2019 00:42:42 - INFO - __main__ -   ***** Eval results  *****
+10/04/2019 00:42:42 - INFO - __main__ -     f1 = 0.8614389652384803
+10/04/2019 00:42:42 - INFO - __main__ -     loss = 0.07064602487454782
+10/04/2019 00:42:42 - INFO - __main__ -     precision = 0.8604651162790697
+10/04/2019 00:42:42 - INFO - __main__ -     recall = 0.8624150210424085
+```
+
+### Emerging and Rare Entities task: WNUT’17 (English NER) dataset
+
+Description of the WNUT’17 task from the [shared task website](http://noisy-text.github.io/2017/index.html):
+
+> The WNUT’17 shared task focuses on identifying unusual, previously-unseen entities in the context of emerging discussions.
+> Named entities form the basis of many modern approaches to other tasks (like event clustering and summarization), but recall on
+> them is a real problem in noisy text - even among annotators. This drop tends to be due to novel entities and surface forms.
+
+Six labels are available in the dataset. An overview can be found on this [page](http://noisy-text.github.io/2017/files/).
+
+#### Data (Download and pre-processing steps)
+
+The dataset can be downloaded from the [official GitHub](https://github.com/leondz/emerging_entities_17) repository.
+
+The following commands show how to prepare the dataset for fine-tuning:
+
+```bash
+mkdir -p data_wnut_17
+
+curl -L 'https://github.com/leondz/emerging_entities_17/raw/master/wnut17train.conll'  | tr '\t' ' ' > data_wnut_17/train.txt.tmp
+curl -L 'https://github.com/leondz/emerging_entities_17/raw/master/emerging.dev.conll' | tr '\t' ' ' > data_wnut_17/dev.txt.tmp
+curl -L 'https://raw.githubusercontent.com/leondz/emerging_entities_17/master/emerging.test.annotated' | tr '\t' ' ' > data_wnut_17/test.txt.tmp
+```
+
+Let's define some variables that we need for further pre-processing steps:
+
+```bash
+export MAX_LENGTH=128
+export BERT_MODEL=bert-large-cased
+```
+
+Here we use the English BERT large model for fine-tuning.
+The `preprocess.py` scripts splits longer sentences into smaller ones (once the max. subtoken length is reached):
+
+```bash
+python3 scripts/preprocess.py data_wnut_17/train.txt.tmp $BERT_MODEL $MAX_LENGTH > data_wnut_17/train.txt
+python3 scripts/preprocess.py data_wnut_17/dev.txt.tmp $BERT_MODEL $MAX_LENGTH > data_wnut_17/dev.txt
+python3 scripts/preprocess.py data_wnut_17/test.txt.tmp $BERT_MODEL $MAX_LENGTH > data_wnut_17/test.txt
+```
+
+In the last pre-processing step, the `labels.txt` file needs to be generated. This file contains all available labels:
+
+```bash
+cat data_wnut_17/train.txt data_wnut_17/dev.txt data_wnut_17/test.txt | cut -d " " -f 2 | grep -v "^$"| sort | uniq > data_wnut_17/labels.txt
+```
+
+#### Run the Pytorch version
+
+Fine-tuning with the PyTorch version can be started using the `run_ner.py` script. In this example we use a JSON-based configuration file.
+
+This configuration file looks like:
+
+```json
+{
+    "data_dir": "./data_wnut_17",
+    "labels": "./data_wnut_17/labels.txt",
+    "model_name_or_path": "bert-large-cased",
+    "output_dir": "wnut-17-model-1",
+    "max_seq_length": 128,
+    "num_train_epochs": 3,
+    "per_device_train_batch_size": 32,
+    "save_steps": 425,
+    "seed": 1,
+    "do_train": true,
+    "do_eval": true,
+    "do_predict": true,
+    "fp16": false
+}
+```
+
+If your GPU supports half-precision training, please set `fp16` to `true`.
+
+Save this JSON-based configuration under `wnut_17.json`. The fine-tuning can be started with `python3 run_ner_old.py wnut_17.json`.
+
+#### Evaluation
+
+Evaluation on development dataset outputs the following:
+
+```bash
+05/29/2020 23:33:44 - INFO - __main__ -   ***** Eval results *****
+05/29/2020 23:33:44 - INFO - __main__ -     eval_loss = 0.26505235286212275
+05/29/2020 23:33:44 - INFO - __main__ -     eval_precision = 0.7008264462809918
+05/29/2020 23:33:44 - INFO - __main__ -     eval_recall = 0.507177033492823
+05/29/2020 23:33:44 - INFO - __main__ -     eval_f1 = 0.5884802220680084
+05/29/2020 23:33:44 - INFO - __main__ -     epoch = 3.0
+```
+
+On the test dataset the following results could be achieved:
+
+```bash
+05/29/2020 23:33:44 - INFO - transformers.trainer -   ***** Running Prediction *****
+05/29/2020 23:34:02 - INFO - __main__ -     eval_loss = 0.30948806500973547
+05/29/2020 23:34:02 - INFO - __main__ -     eval_precision = 0.5840108401084011
+05/29/2020 23:34:02 - INFO - __main__ -     eval_recall = 0.3994439295644115
+05/29/2020 23:34:02 - INFO - __main__ -     eval_f1 = 0.47440836543753434
+```
+
+WNUT’17 is a very difficult task. Current state-of-the-art results on this dataset can be found [here](http://nlpprogress.com/english/named_entity_recognition.html).

examples/token-classification/run_old.sh → examples/legacy/token-classification/run.sh

@@ -20,7 +20,7 @@ export NUM_EPOCHS=3
 export SAVE_STEPS=750
 export SEED=1
 
-python3 run_ner_old.py \
+python3 run_ner.py \
 --task_type NER \
 --data_dir . \
 --labels ./labels.txt \

examples/token-classification/run_chunk.sh → examples/legacy/token-classification/run_chunk.sh

@@ -21,7 +21,7 @@ export NUM_EPOCHS=3
 export SAVE_STEPS=750
 export SEED=1
 
-python3 run_ner_old.py \
+python3 run_ner.py \
 --task_type Chunk \
 --data_dir . \
 --model_name_or_path $BERT_MODEL \

examples/token-classification/run_pos.sh → examples/legacy/token-classification/run_pos.sh

@@ -21,7 +21,7 @@ export NUM_EPOCHS=3
 export SAVE_STEPS=750
 export SEED=1
 
-python3 run_ner_old.py \
+python3 run_ner.py \
 --task_type POS \
 --data_dir . \
 --model_name_or_path $BERT_MODEL \

examples/multiple-choice/README.md

+<!---
+Copyright 2020 The HuggingFace Team. All rights reserved.
+
+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.
+-->
+
 ## Multiple Choice
 
 Based on the script [`run_multiple_choice.py`]().

examples/multiple-choice/requirements.txt

+sentencepiece != 0.1.92
+protobuf

examples/question-answering/README.md

+<!---
+Copyright 2020 The HuggingFace Team. All rights reserved.
 
+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.
+-->
 
 ## SQuAD
 
-Based on the script [`run_squad.py`](https://github.com/huggingface/transformers/blob/master/examples/question-answering/run_squad.py).
+Based on the script [`run_qa.py`](https://github.com/huggingface/transformers/blob/master/examples/question-answering/run_qa.py).
+
+**Note:** This script only works with models that have a fast tokenizer (backed by the 🤗 Tokenizers library) as it
+uses special features of those tokenizers. You can check if your favorite model has a fast tokenizer in
+[this table](https://huggingface.co/transformers/index.html#bigtable), if it doesn't you can still use the old version
+of the script.
+
+The old version of this script can be found [here](https://github.com/huggingface/transformers/blob/master/examples/contrib/legacy/question-answering/run_squad.py).
 
 #### Fine-tuning BERT on SQuAD1.0
 

examples/question-answering/requirements.txt

+datasets >= 1.1.3

examples/research_projects/README.md

+<!---
+Copyright 2020 The HuggingFace Team. All rights reserved.
+
+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.
+-->
+
+# Research projects
+
+This folder contains various research projects using 🤗 Transformers. They are not maintained and require a specific
+version of 🤗 Transformers that is indicated in the requirements file of each folder. Updating them to the most recent version of the library will require some work.
+
+To use any of them, just run the command
+```
+pip install -r requirements.txt
+```
+inside the folder of your choice.
+
+If you need help with any of those, contact the author(s), indicated at the top of the `README` of each folder.