mengta666/huggingface_github huggingface dataset:
Issue: When will the remaining math_dataset modules be added as dataset objects

Currently only the algebra_linear_1d is supported. Is there a timeline for making the other modules supported. If no timeline is established, how can I help?

Comments:
On a similar note it would be nice to differentiate between train-easy, train-medium, and train-hard

Hi @tylerroost, we don't have a timeline for this at the moment.
If you want to give it a look we would be happy to review a PR on it.
Also, the library is one week old so everything is quite barebones, in particular the doc.
You should expect some bumps on the road.

To get you started, you can check the datasets scripts in the `./datasets` folder on the repo and find the one on math_datasets that will need to be modified. Then you should check the original repository on the math_dataset to see where the other files to download are located and what is the expected format for the various parts of the dataset.

To get a general overview on how datasets scripts are written and used, you can read the nice tutorial on how to add a new dataset for TensorFlow Dataset [here](https://www.tensorflow.org/datasets/add_dataset), our API is not exactly identical but it can give you a high-level overview.

Thanks I'll give it a look
Issue: Weird-ish: Not creating unique caches for different phases

Sample code:

```python
import nlp
dataset = nlp.load_dataset('boolq')

def func1(x):
    return x

def func2(x):
    return None

train_output = dataset["train"].map(func1)
valid_output = dataset["validation"].map(func1)
print()
print(len(train_output), len(valid_output))
# Output: 9427 9427
```

The map method in both cases seem to be pointing to the same cache, so the latter call based on the validation data will return the processed train data cache.

What's weird is that the following doesn't seem to be an issue:

```python
train_output = dataset["train"].map(func2)
valid_output = dataset["validation"].map(func2)
print()
print(len(train_output), len(valid_output))
# 9427 3270
```

Comments:
Looks like a duplicate of #120.
This is already fixed on master. We'll do a new release on pypi soon

Good catch, it looks fixed.
Issue: [Bug] labels of glue/ax are all -1 

```
ax = nlp.load_dataset('glue', 'ax')
for i in range(30): print(ax['test'][i]['label'], end=', ')
```
```
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 
```

Comments:
This is the test set given by the Glue benchmark. The labels are not provided, and therefore set to -1.

Ah, yeah. Why it didn’t occur to me. 😂
Thank you for your comment.
Issue: [Feature request] separate split name and split instructions

Currently, the name of an nlp.NamedSplit is parsed in arrow_reader.py and used as the instruction.

This makes it impossible to have several training sets, which can occur when:
- A dataset corresponds to a collection of sub-datasets
- A dataset was built in stages, adding new examples at each stage

Would it be possible to have two separate fields in the Split class, a name /instruction and a unique ID that is used as the key in the builder's split_dict ?

Comments:
If your dataset is a collection of sub-datasets, you should probably consider having one config per sub-dataset. For example for Glue, we have sst2, mnli etc.
If you want to have multiple train sets (for example one per stage). The easiest solution would be to name them `nlp.Split("train_stage1")`, `nlp.Split("train_stage2")`, etc. or something like that.

Thanks for the tip! I ended up setting up three different versions of the dataset with their own configs.

for the named splits, I was trying with `nlp.Split("train-stage1")`, which fails. Changing to `nlp.Split("train_stage1")` works :) I looked for examples of what works in the code comments, it may be worth adding some examples of valid/invalid names in there?
Issue: Clone not working on Windows environment

Cloning in a windows environment is not working because of use of special character '?' in folder name ..
Please consider changing the folder name ....
Reference to folder -
nlp/datasets/cnn_dailymail/dummy/3.0.0/3.0.0/dummy_data-zip-extracted/dummy_data/uc?export=download&id=0BwmD_VLjROrfM1BxdkxVaTY2bWs/dailymail/stories/

error log:
fatal: cannot create directory at 'datasets/cnn_dailymail/dummy/3.0.0/3.0.0/dummy_data-zip-extracted/dummy_data/uc?export=download&id=0BwmD_VLjROrfM1BxdkxVaTY2bWs': Invalid argument



Comments:
Should be fixed on master now :)

Thanks @lhoestq 👍  Now I can uninstall WSL and get back to work with windows.🙂
Issue: Add a method to shuffle a dataset

Could maybe be a `dataset.shuffle(generator=None, seed=None)` signature method.

Also, we could maybe have a clear indication of which method modify in-place and which methods return/cache a modified dataset. I kinda like torch conversion of having an underscore suffix for all the methods which modify a dataset in-place. What do you think?

Comments:
+1 for the naming convention

About the `shuffle` method, from my understanding it should be done in `Dataloader` (better separation between dataset processing - usage)

+1 for shuffle in `Dataloader`. 
Some `Dataloader` just store idxs of dataset and just shuffle those idxs, which might(?) be faster than do shuffle in dataset, especially when doing shuffle every epoch.

Also +1 for the naming convention.

As you might already know the issue of dataset shuffling came up in the nlp code [walkthrough](https://youtu.be/G3pOvrKkFuk?t=3204) by Yannic Kilcher


We added the `.shuffle` method :)

Closing this one.
Issue: Add Spanish POR and NER Datasets

Hi guys,
In order to cover multilingual support a little step could be adding standard Datasets used for Spanish NER and POS tasks.
I can provide it in raw and preprocessed formats.

Comments:
Hello @mrm8488, are these datasets official datasets published in an NLP/CL/ML venue?

What about this one: https://github.com/ccasimiro88/TranslateAlignRetrieve?
Issue: [Feature request] Add cos-e v1.0

I noticed the second release of cos-e (v1.11) is included in this repo. I wanted to request inclusion of v1.0, since this is the version on which results are reported on in [the paper](https://www.aclweb.org/anthology/P19-1487/), and v1.11 has noted [annotation](https://github.com/salesforce/cos-e/issues/2) [issues](https://arxiv.org/pdf/2004.14546.pdf).

Comments:
Sounds good, @mariamabarham do you want to give a look?
I think we should have two configurations so we can allow either version of the dataset to be loaded with the `1.0` version being the default maybe.

Cc some authors of the great cos-e: @nazneenrajani @bmccann

cos_e v1.0 is related to CQA v1.0 but only CQA v1.11 dataset is available on their website. Indeed their is lots of ids in cos_e v1, which are  not in CQA v1.11  or the other way around.
@sarahwie, @thomwolf, @nazneenrajani,  @bmccann  do you know where I can  find CQA v1.0


@mariamabarham I'm also not sure where to find CQA 1.0. Perhaps it's not possible to include this version of the dataset. I'll close the issue if that's the case.

I do have a copy of the dataset. I can upload it to our repo.

Great @nazneenrajani. let me know once done.
Thanks

@mariamabarham @sarahwie I added them to the cos-e repo https://github.com/salesforce/cos-e/tree/master/data/v1.0

You can now do
```python
from nlp import load_dataset
cos_e = load_dataset("cos_e", "v1.0")
```
Thanks @mariamabarham !

Thanks!

@mariamabarham Just wanted to note that default behavior `cos_e = load_dataset("cos_e")` now loads `v1.0`. Not sure if this is intentional (but the flag specification does work as intended). 

> @mariamabarham Just wanted to note that default behavior `cos_e = load_dataset("cos_e")` now loads `v1.0`. Not sure if this is intentional (but the flag specification does work as intended).

In the new version of `nlp`, if you try `cos_e = load_dataset("cos_e")` it throws this error:
```
ValueError: Config name is missing.
Please pick one among the available configs: ['v1.0', 'v1.11']
Example of usage:
	`load_dataset('cos_e', 'v1.0')`
```
For datasets with at least two configurations, we now force the user to pick one (no default)
Issue: nlp.load_dataset() gives "TypeError: list_() takes exactly one argument (2 given)"

I'm trying to load datasets from nlp but there seems to have error saying 
"TypeError: list_() takes exactly one argument (2 given)"

gist can be found here
https://gist.github.com/saahiluppal/c4b878f330b10b9ab9762bc0776c0a6a

Comments:
You can just run: 
`val = nlp.load_dataset('squad')` 

if you want to have just the validation script you can also do:

`val = nlp.load_dataset('squad', split="validation")`

If you want to load a local dataset, make sure you include a `./` before the folder name. 

This happens by just doing run all cells on colab ... I assumed the colab example is broken. 

Oh I see you might have a wrong version of pyarrow install on the colab -> could you try the following. Add these lines to the beginning of your notebook, restart the runtime and run it again:
```
!pip uninstall -y -qq pyarrow
!pip uninstall -y -qq nlp
!pip install -qq git+https://github.com/huggingface/nlp.git
```

> Oh I see you might have a wrong version of pyarrow install on the colab -> could you try the following. Add these lines to the beginning of your notebook, restart the runtime and run it again:
> 
> ```
> !pip uninstall -y -qq pyarrow
> !pip uninstall -y -qq nlp
> !pip install -qq git+https://github.com/huggingface/nlp.git
> ```

Tried, having the same error.

Can you post a link here of your colab? I'll make a copy of it and see what's wrong

This should be fixed in the current version of the notebook. You can try it again

Also see: https://github.com/huggingface/nlp/issues/222

I am getting this error when running this command
```
val = nlp.load_dataset('squad', split="validation")
```

FileNotFoundError: [Errno 2] No such file or directory: '/root/.cache/huggingface/datasets/squad/plain_text/1.0.0/dataset_info.json'

Can anybody help?

It seems like your download was corrupted :-/ Can you run the following command: 

```
rm -r /root/.cache/huggingface/datasets
```

to delete the cache completely and rerun the download? 

I tried the notebook again today and it worked without barfing. 👌
Issue: Meta-datasets (GLUE/XTREME/...) – Special care to attributions and citations

Meta-datasets are interesting in terms of standardized benchmarks but they also have specific behaviors, in particular in terms of attribution and authorship. It's very important that each specific dataset inside a meta dataset is properly referenced and the citation/specific homepage/etc are very visible and accessible and not only the generic citation of the meta-dataset itself.

Let's take GLUE as an example:

The configuration has the citation for each dataset included (e.g. [here](https://github.com/huggingface/nlp/blob/master/datasets/glue/glue.py#L154-L161)) but it should be copied inside the dataset info so that, when people access `dataset.info.citation` they get both the citation for GLUE and the citation for the specific datasets inside GLUE that they have loaded.

Comments:
As @yoavgo suggested, there should be the possibility to call a function like  nlp.bib that outputs all bibtex ref from the datasets and models actually used and eventually nlp.bib.forreadme that would output the same info + versions numbers so they can be included in a readme.md file.

Actually, double checking with @mariamabarham, we already have this feature I think.

It's like this currently:
```python
>>> from nlp import load_dataset
>>> 
>>> dataset = load_dataset('glue', 'cola', split='train')
>>> print(dataset.info.citation)
@article{warstadt2018neural,
  title={Neural Network Acceptability Judgments},
  author={Warstadt, Alex and Singh, Amanpreet and Bowman, Samuel R},
  journal={arXiv preprint arXiv:1805.12471},
  year={2018}
}
@inproceedings{wang2019glue,
  title={{GLUE}: A Multi-Task Benchmark and Analysis Platform for Natural Language Understanding},
  author={Wang, Alex and Singh, Amanpreet and Michael, Julian and Hill, Felix and Levy, Omer and Bowman, Samuel R.},
  note={In the Proceedings of ICLR.},
  year={2019}
}

Note that each GLUE dataset has its own citation. Please see the source to see
the correct citation for each contained dataset.
```

What do you think @dseddah?

Looks good but why would there be a difference between the ref in the source and the one to be printed? 

Yes, I think we should remove this warning @mariamabarham.

It's probably a relic of tfds which didn't have the same way to access citations.
Issue: [Feature request] Add Ubuntu Dialogue Corpus dataset

https://github.com/rkadlec/ubuntu-ranking-dataset-creator or http://dataset.cs.mcgill.ca/ubuntu-corpus-1.0/

Comments:
@AlphaMycelium the Ubuntu Dialogue Corpus [version 2]( https://github.com/rkadlec/ubuntu-ranking-dataset-creator) is added. Note that it requires a manual download by following the download instructions in the [repos]( https://github.com/rkadlec/ubuntu-ranking-dataset-creator).
Maybe we can close this issue for now?
Issue: _download_and_prepare() got an unexpected keyword argument 'verify_infos'

# Reproduce
In Colab,
```
%pip install -q  nlp
%pip install -q apache_beam mwparserfromhell

dataset = nlp.load_dataset('wikipedia')
```
get
```
Downloading and preparing dataset wikipedia/20200501.aa (download: Unknown size, generated: Unknown size, total: Unknown size) to /root/.cache/huggingface/datasets/wikipedia/20200501.aa/1.0.0...

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-6-52471d2a0088> in <module>()
----> 1 dataset = nlp.load_dataset('wikipedia')

1 frames

/usr/local/lib/python3.6/dist-packages/nlp/load.py in load_dataset(path, name, version, data_dir, data_files, split, cache_dir, download_config, download_mode, ignore_verifications, save_infos, **config_kwargs)
    515         download_mode=download_mode,
    516         ignore_verifications=ignore_verifications,
--> 517         save_infos=save_infos,
    518     )
    519 

/usr/local/lib/python3.6/dist-packages/nlp/builder.py in download_and_prepare(self, download_config, download_mode, ignore_verifications, save_infos, dl_manager, **download_and_prepare_kwargs)
    361                 verify_infos = not save_infos and not ignore_verifications
    362                 self._download_and_prepare(
--> 363                     dl_manager=dl_manager, verify_infos=verify_infos, **download_and_prepare_kwargs
    364                 )
    365                 # Sync info

TypeError: _download_and_prepare() got an unexpected keyword argument 'verify_infos'
```

Comments:
Same error for dataset 'wiki40b'

Should be fixed on master :)
Issue: Error with sklearn train_test_split

It would be nice if we could use sklearn `train_test_split` to quickly generate subsets from the dataset objects returned by `nlp.load_dataset`. At the moment the code:

```python
data = nlp.load_dataset('imdb', cache_dir=data_cache)
f_half, s_half = train_test_split(data['train'], test_size=0.5, random_state=seed)
```
throws:
```
ValueError: Can only get row(s) (int or slice) or columns (string).
```
It's not a big deal, since there are other ways to split the data, but it would be a cool thing to have.

Comments:
Indeed. Probably we will want to have a similar method directly in the library

Related: #166
Issue: ArrowTypeError in squad metrics

`squad_metric.compute` is giving following error
```
ArrowTypeError: Could not convert [{'text': 'Denver Broncos'}, {'text': 'Denver Broncos'}, {'text': 'Denver Broncos'}] with type list: was not a dict, tuple, or recognized null value for conversion to struct type
```

This is how my predictions and references look like
```
predictions[0]
# {'id': '56be4db0acb8001400a502ec', 'prediction_text': 'Denver Broncos'}
```

```
references[0]
# {'answers': [{'text': 'Denver Broncos'},
  {'text': 'Denver Broncos'},
  {'text': 'Denver Broncos'}],
 'id': '56be4db0acb8001400a502ec'}
```

These are structured as per the `squad_metric.compute` help string.

Comments:
There was an issue in the format, thanks.
Now you can do
```python3
squad_dset = nlp.load_dataset("squad")
squad_metric = nlp.load_metric("/Users/quentinlhoest/Desktop/hf/nlp-bis/metrics/squad")
predictions = [
    {"id": v["id"], "prediction_text": v["answers"]["text"][0]}  # take first possible answer
    for v in squad_dset["validation"]
]
squad_metric.compute(predictions, squad_dset["validation"])
```

and the expected format is 
```
Args:
    predictions: List of question-answers dictionaries with the following key-values:
        - 'id': id of the question-answer pair as given in the references (see below)
        - 'prediction_text': the text of the answer
    references: List of question-answers dictionaries with the following key-values:
        - 'id': id of the question-answer pair (see above),
        - 'answers': a Dict {'text': list of possible texts for the answer, as a list of strings}
```
Issue: [Question] Using/adding a local dataset

Users may want to either create/modify a local copy of a dataset, or use a custom-built dataset with the same `Dataset` API as externally downloaded datasets.

It appears to be possible to point to a local dataset path rather than downloading the external ones, but I'm not exactly sure how to go about doing this.

A notebook/example script demonstrating this would be very helpful.

Comments:
Hi @zphang,

So you can just give the local path to a dataset script file and it should work.

Here is an example:
- you can download one of the scripts in the `datasets` folder of the present repo (or clone the repo)
- then you can load it with `load_dataset('PATH/TO/YOUR/LOCAL/SCRIPT.py')`

Does it make sense?

Could you give a more concrete example, please? 

I looked up wikitext dataset script from the repo. Should I just overwrite the `data_file` on line 98 to point to the local dataset directory? Would it work for different configurations of wikitext (wikitext2, wikitext103 etc.)?

Or maybe we can use DownloadManager to specify local dataset location? In that case, where do we use DownloadManager instance?

Thanks

Hi @MaveriQ , although what I am doing is to commit a new dataset, but I think looking at imdb script might help.
You may want to use `dl_manager.download_custom`, give it a url(arbitrary string), a custom_download(arbitrary function) and return a path, and finally use _get sample to fetch a sample.

The download manager supports local directories. You can specify a local directory instead of a url and it should work.

Closing this one.
Feel free to re-open if you have other questions :)
Issue: [Feature Request] Add the OpenWebText dataset

The OpenWebText dataset is an open clone of OpenAI's WebText dataset. It can be used to train ELECTRA as is specified in the [README](https://www.github.com/google-research/electra).

More information and the download link are available [here](https://skylion007.github.io/OpenWebTextCorpus/).

Comments:
We're experimenting with hosting the OpenWebText corpus on Zenodo for easier downloading. https://zenodo.org/record/3834942#.Xs1w8i-z2J8

Closing since it's been added in #660
Issue: [Feature request] Add Toronto BookCorpus dataset

I know the copyright/distribution of this one is complex, but it would be great to have! That, combined with the existing `wikitext`, would provide a complete dataset for pretraining models like BERT.

Comments:
As far as I understand, `wikitext` is refer to `WikiText-103` and `WikiText-2` that created by researchers in Salesforce, and mostly used in traditional language modeling.

You might want to say `wikipedia`, a dump from wikimedia foundation.

Also I would like to have Toronto BookCorpus too ! Though it involves copyright problem...

Hi, @lhoestq, just a reminder that this is solved by #248 .😉
Issue: Loading GLUE dataset loads CoLA by default

If I run:

```python
dataset = nlp.load_dataset('glue')
```
The resultant dataset seems to be CoLA be default, without throwing any error. This is in contrast to calling:

```python
metric = nlp.load_metric("glue")
```
which throws an error telling the user that they need to specify a task in GLUE. Should the same apply for loading datasets?

Comments:
As a follow-up to this: It looks like the actual GLUE task name is supplied as the `name` argument. Is there a way to check what `name`s/sub-datasets are available under a grouping like GLUE? That information doesn't seem to be readily available in info from `nlp.list_datasets()`.

Edit: I found the info under `Glue.BUILDER_CONFIGS`

Yes so the first config is loaded by default when no `name` is supplied but for GLUE this should probably throw an error indeed.

We can probably just add an `__init__` at the top of the `class Glue(nlp.GeneratorBasedBuilder)` in the `glue.py` script which does this check:
```
class Glue(nlp.GeneratorBasedBuilder):
    def __init__(self, *args, **kwargs):
        assert 'name' in kwargs and kwargs[name] is not None, "Glue has to be called with a configuration name"
        super(Glue, self).__init__(*args, **kwargs)
```

An error is raised if the sub-dataset is not specified :)
```
ValueError: Config name is missing.
Please pick one among the available configs: ['cola', 'sst2', 'mrpc', 'qqp', 'stsb', 'mnli', 'mnli_mismatched', 'mnli_matched', 'qnli', 'rte', 'wnli', 'ax']
Example of usage:
	`load_dataset('glue', 'cola')`
```
Issue: [Feature request] Add Google Natural Question dataset

Would be great to have https://github.com/google-research-datasets/natural-questions as an alternative to SQuAD.

Comments:
Indeed, I think this one is almost ready cc @lhoestq 

I'm doing the latest adjustments to make the processing of the dataset run on Dataflow

Is there an update to this? It will be very beneficial for the QA community!

Still work in progress :)
The idea is to have the dataset already processed somewhere so that the user only have to download the processed files. I'm also doing it for wikipedia.

Super appreciate your hard work !!
I'll cross my fingers and hope easily loadable wikipedia dataset will come soon. 

Quick update on NQ: due to some limitations I met using apache beam + parquet I was not able to use the dataset in a nested parquet structure in python to convert it to our Apache Arrow format yet.
However we had planned to change this conversion step anyways so we'll make just sure that it enables to process and convert the NQ dataset to arrow.

NQ was added in #427 🎉
Issue: 🐛 `map` not working

I'm trying to run a basic example (mapping function to add a prefix).  
[Here is the colab notebook I'm using.](https://colab.research.google.com/drive/1YH4JCAy0R1MMSc-k_Vlik_s1LEzP_t1h?usp=sharing)

```python
import nlp

dataset = nlp.load_dataset('squad', split='validation[:10%]')

def test(sample):
    sample['title'] = "test prefix @@@ " + sample["title"]
    return sample

print(dataset[0]['title'])
dataset.map(test)
print(dataset[0]['title'])
```
Output :
> Super_Bowl_50
Super_Bowl_50

Expected output :
> Super_Bowl_50
test prefix @@@ Super_Bowl_50

Comments:
I didn't assign the output 🤦‍♂️

```python
dataset.map(test)
```

should be :

```python
dataset = dataset.map(test)
```
Issue: 🐛 Colab : type object 'pyarrow.lib.RecordBatch' has no attribute 'from_struct_array'

I'm trying to load CNN/DM dataset on Colab.

[Colab notebook](https://colab.research.google.com/drive/11Mf7iNhIyt6GpgA1dBEtg3cyMHmMhtZS?usp=sharing)

But I meet this error :

> AttributeError: type object 'pyarrow.lib.RecordBatch' has no attribute 'from_struct_array'


Comments:
It's strange, after installing `nlp` on Colab, the `pyarrow` version seems fine from `pip` but not from python :

```python
import pyarrow

!pip show pyarrow
print("version = {}".format(pyarrow.__version__))
```

> Name: pyarrow
Version: 0.17.0
Summary: Python library for Apache Arrow
Home-page: https://arrow.apache.org/
Author: None
Author-email: None
License: Apache License, Version 2.0
Location: /usr/local/lib/python3.6/dist-packages
Requires: numpy
Required-by: nlp, feather-format
> 
> version = 0.14.1

Ok I just had to restart the runtime after installing `nlp`. After restarting, the version of `pyarrow` is fine.
Issue: ❓ How to apply a map to all subsets ?

I'm working with CNN/DM dataset, where I have 3 subsets : `train`, `test`, `validation`.

Should I apply my map function on the subsets one by one ?

```python
import nlp

cnn_dm = nlp.load_dataset('cnn_dailymail')
for corpus in ['train', 'test', 'validation']:
         cnn_dm[corpus] = cnn_dm[corpus].map(my_func)
```

Or is there a better way to do this ?

Comments:
That's the way!
Issue: ❓ How to remove specific rows of a dataset ?

I saw on the [example notebook](https://colab.research.google.com/github/huggingface/nlp/blob/master/notebooks/Overview.ipynb#scrollTo=efFhDWhlvSVC) how to remove a specific column :

```python
dataset.drop('id')
```

But I didn't find how to remove a specific row. 

**For example, how can I remove all sample with `id` < 10 ?**

Comments:
Hi, you can't do that at the moment.

Can you do it by now? Coz it would be awfully helpful!

you can convert dataset object to pandas and remove a feature and convert back to dataset .

That's what I ended up doing too. but it feels like a workaround to a feature that should be added to the datasets class.
Issue: 🐛 Trying to use ROUGE metric : pyarrow.lib.ArrowInvalid: Column 1 named references expected length 534 but got length 323

I'm trying to use rouge metric.

I have to files : `test.pred.tokenized` and `test.gold.tokenized` with each line containing a sentence.  
I tried :

```python
import nlp

rouge = nlp.load_metric('rouge')
with open("test.pred.tokenized") as p, open("test.gold.tokenized") as g:
    for lp, lg in zip(p, g):
            rouge.add(lp, lg)
```

But I meet following error :

> pyarrow.lib.ArrowInvalid: Column 1 named references expected length 534 but got length 323

---

Full stack-trace :

```
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/home/me/.venv/transformers/lib/python3.6/site-packages/nlp/metric.py", line 224, in add
    self.writer.write_batch(batch)
  File "/home/me/.venv/transformers/lib/python3.6/site-packages/nlp/arrow_writer.py", line 148, in write_batch
    pa_table: pa.Table = pa.Table.from_pydict(batch_examples, schema=self._schema)
  File "pyarrow/table.pxi", line 1550, in pyarrow.lib.Table.from_pydict
  File "pyarrow/table.pxi", line 1503, in pyarrow.lib.Table.from_arrays
  File "pyarrow/public-api.pxi", line 390, in pyarrow.lib.pyarrow_wrap_table
  File "pyarrow/error.pxi", line 85, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Column 1 named references expected length 534 but got length 323
```

(`nlp` installed from source)

Comments:
Can you share your data files or a minimally reproducible example?

Sure, [here is a Colab notebook](https://colab.research.google.com/drive/1uiS89fnHMG7HV_cYxp3r-_LqJQvNNKs9?usp=sharing) reproducing the error.

> ArrowInvalid: Column 1 named references expected length 36 but got length 56

This is because `add` takes as input a batch of elements and you provided only one. I think we should have `add` for one prediction/reference and `add_batch` for a batch of predictions/references. This would make it more coherent with the way we use Arrow.

Let me do this change

Thanks for noticing though. I was mainly used to do `.compute` directly ^^

Thanks @lhoestq it works :)
Issue: AttributeError: 'dict' object has no attribute 'info'

I'm trying to access the information of CNN/DM dataset :

```python
cnn_dm = nlp.load_dataset('cnn_dailymail')
print(cnn_dm.info)
```

returns :

> AttributeError: 'dict' object has no attribute 'info'

Comments:
I could access the info by first accessing the different splits :

```python
import nlp

cnn_dm = nlp.load_dataset('cnn_dailymail')
print(cnn_dm['train'].info)
```

Information seems to be duplicated between the subsets :

```python
print(cnn_dm["train"].info == cnn_dm["test"].info == cnn_dm["validation"].info)
# True
```

Is it expected ?

Good point @Colanim ! What happens under the hood when running:

```python
import nlp

cnn_dm = nlp.load_dataset('cnn_dailymail')
```

is that for every split in `cnn_dailymail`, a different dataset object (which all holds the same info) is created. This has the advantages that the datasets are easily separable in a training setup. 
Also note that you can load e.g. only the `train` split of the dataset via:

```python
cnn_dm_train = nlp.load_dataset('cnn_dailymail', split="train")
print(cnn_dm_train.info)
```

I think we should make the `info` object slightly different when creating the dataset for each split - at the moment it contains for example the variable `splits` which should maybe be renamed to `split` and contain only one `SplitInfo` object ...
Issue: Couldn't reach CNN/DM dataset

I can't get CNN / DailyMail dataset.

```python
import nlp

assert "cnn_dailymail" in [dataset.id for dataset in nlp.list_datasets()]
cnn_dm = nlp.load_dataset('cnn_dailymail')
```

[Colab notebook](https://colab.research.google.com/drive/1zQ3bYAVzm1h0mw0yWPqKAg_4EUlSx5Ex?usp=sharing)

gives following error :

```
ConnectionError: Couldn't reach https://s3.amazonaws.com/datasets.huggingface.co/nlp/cnn_dailymail/cnn_dailymail.py
```

Comments:
Installing from source (instead of Pypi package) solved the problem.
Issue: [Checksums] Error for some datasets

The checksums command works very nicely for `squad`. But for `crime_and_punish` and `xnli`, 
the same bug happens:

When running: 
```
python nlp-cli nlp-cli test xnli --save_checksums
```

leads to:

```
  File "nlp-cli", line 33, in <module>
    service.run()
  File "/home/patrick/python_bin/nlp/commands/test.py", line 61, in run
    ignore_checksums=self._ignore_checksums,
  File "/home/patrick/python_bin/nlp/builder.py", line 383, in download_and_prepare
    self._download_and_prepare(dl_manager=dl_manager, download_config=download_config)
  File "/home/patrick/python_bin/nlp/builder.py", line 627, in _download_and_prepare
    dl_manager=dl_manager, max_examples_per_split=download_config.max_examples_per_split,
  File "/home/patrick/python_bin/nlp/builder.py", line 431, in _download_and_prepare
    split_generators = self._split_generators(dl_manager, **split_generators_kwargs)
  File "/home/patrick/python_bin/nlp/datasets/xnli/8bf4185a2da1ef2a523186dd660d9adcf0946189e7fa5942ea31c63c07b68a7f/xnli.py", line 95, in _split_generators
    dl_dir = dl_manager.download_and_extract(_DATA_URL)
  File "/home/patrick/python_bin/nlp/utils/download_manager.py", line 246, in download_and_extract
    return self.extract(self.download(url_or_urls))
  File "/home/patrick/python_bin/nlp/utils/download_manager.py", line 186, in download
    self._record_sizes_checksums(url_or_urls, downloaded_path_or_paths)
  File "/home/patrick/python_bin/nlp/utils/download_manager.py", line 166, in _record_sizes_checksums
    self._recorded_sizes_checksums[url] = get_size_checksum(path)
  File "/home/patrick/python_bin/nlp/utils/checksums_utils.py", line 81, in get_size_checksum
    with open(path, "rb") as f:
TypeError: expected str, bytes or os.PathLike object, not tuple
```


Comments:
@lhoestq - could you take a look? It's not very urgent though!

Fixed with 06882b4

Now your command works :)
Note that you can also do
```
nlp-cli test datasets/nlp/xnli --save_checksums
```
So that it will save the checksums directly in the right directory.

Awesome!
Issue: Error when citation is not given in the DatasetInfo

The following error is raised when the `citation` parameter is missing when we instantiate a `DatasetInfo`:
```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/jplu/dev/jplu/datasets/src/nlp/info.py", line 338, in __repr__
    citation_pprint = _indent('"""{}"""'.format(self.citation.strip()))
AttributeError: 'NoneType' object has no attribute 'strip'
```

I propose to do the following change in the `info.py` file. The method:
```python
def __repr__(self):
        splits_pprint = _indent("\n".join(["{"] + [
                "    '{}': {},".format(k, split.num_examples)
                for k, split in sorted(self.splits.items())
        ] + ["}"]))
        features_pprint = _indent(repr(self.features))
        citation_pprint = _indent('"""{}"""'.format(self.citation.strip()))
        return INFO_STR.format(
                name=self.name,
                version=self.version,
                description=self.description,
                total_num_examples=self.splits.total_num_examples,
                features=features_pprint,
                splits=splits_pprint,
                citation=citation_pprint,
                homepage=self.homepage,
                supervised_keys=self.supervised_keys,
                # Proto add a \n that we strip.
                license=str(self.license).strip())
```
Becomes:
```python
def __repr__(self):
        splits_pprint = _indent("\n".join(["{"] + [
                "    '{}': {},".format(k, split.num_examples)
                for k, split in sorted(self.splits.items())
        ] + ["}"]))
        features_pprint = _indent(repr(self.features))
        ## the strip is done only is the citation is given
        citation_pprint = self.citation

        if self.citation:
            citation_pprint = _indent('"""{}"""'.format(self.citation.strip()))
        return INFO_STR.format(
                name=self.name,
                version=self.version,
                description=self.description,
                total_num_examples=self.splits.total_num_examples,
                features=features_pprint,
                splits=splits_pprint,
                citation=citation_pprint,
                homepage=self.homepage,
                supervised_keys=self.supervised_keys,
                # Proto add a \n that we strip.
                license=str(self.license).strip())
```
And now it is ok. @thomwolf are you ok with this fix?

Comments:
Yes looks good to me.
Note that we may refactor quite strongly the `info.py` to make it a lot simpler (it's very complicated for basically a dictionary of info I think)

No, problem ^^ It might just be a temporary fix :)

Fixed.
Issue: [Feature] Keep the list of labels of a dataset as metadata

It would be useful to keep the list of the labels of a dataset as metadata. Either directly in the `DatasetInfo` or in the Arrow metadata.

Comments:
Yes! I see mostly two options for this:
- a `Feature` approach like currently (but we might deprecate features)
- wrapping in a smart way the Dictionary arrays of Arrow: https://arrow.apache.org/docs/python/data.html?highlight=dictionary%20encode#dictionary-arrays

I would have a preference for the second bullet point.

This should be accessible now as a feature in dataset.info.features (and even have the mapping methods).

Perfect! Well done!!

Hi,
I hope we could get a better documentation.
It took me more than 1 hour to found this way to get the label information.

Yes we are working on the doc right now, should be in the next release quite soon.
Issue: [Feature] More dataset outputs

Add the following dataset outputs:

- Spark
- Pandas

Comments:
Yes!
- pandas will be a one-liner in `arrow_dataset`: https://arrow.apache.org/docs/python/generated/pyarrow.Table.html#pyarrow.Table.to_pandas
- for Spark I have no idea. let's investigate that at some point

For Spark it looks to be pretty straightforward as well https://spark.apache.org/docs/latest/sql-pyspark-pandas-with-arrow.html but looks to be having a dependency to Spark is necessary, then nevermind we can skip it

Now Pandas is available.