helmo/github-issues huggingface dataset:
`map` with `num_proc` > 1 leads to OOM
State: open | Author: bhavitvyamalik (CONTRIBUTOR)

### Describe the bug

When running `map` on parquet dataset loaded from local machine, the RAM usage increases linearly eventually leading to OOM. I was wondering if I should I save the `cache_file` after every n steps in order to prevent this?

### Steps to reproduce the bug



```
ds = load_dataset("parquet", data_files=dataset_path, split="train")
ds = ds.shard(num_shards=4, index=0)

ds = ds.cast_column("audio", datasets.features.Audio(sampling_rate=16_000))
ds = ds.map(prepare_dataset,
            num_proc=32,
            writer_batch_size=1000,
            keep_in_memory=False,
            desc="preprocess dataset")
```

```
def prepare_dataset(batch):
    # load audio
    sample = batch["audio"]

    inputs = feature_extractor(sample["array"], sampling_rate=16000)
    batch["input_values"] = inputs.input_values[0]
    batch["input_length"] = len(sample["array"].squeeze())

    return batch
```

### Expected behavior

It shouldn't run into OOM problem.

### Environment info

- `datasets` version: 2.18.0
- Platform: Linux-5.4.0-91-generic-x86_64-with-glibc2.17
- Python version: 3.8.19
- `huggingface_hub` version: 0.22.2
- PyArrow version: 15.0.2
- Pandas version: 2.0.3
- `fsspec` version: 2024.2.0

Comments: Hi ! You can try to reduce `writer_batch_size`. It corresponds to the number of samples that stay in RAM before being flushed to disk
Allow deleting a subset/config from a no-script dataset
State: closed | Author: albertvillanova (MEMBER)
Labels: name: enhancement

As proposed by @BramVanroy, it would be neat to have this functionality through the API.

Comments: Probably best to implement this as a CLI command?

Thanks for your comment, @mariosasko. Or maybe both (in Python and as CLI command)? The Python command would be just the reverse of `push_to_hub`...

I am working on a draft implementation, so we can discuss about the API and UX.

2nd time I've come here in the past few days so for reference this doesn't work for me at the moment (token auth error despite successful `whoami` and all auths applied) so I resorted to [reverting](https://discuss.huggingface.co/t/how-to-revert-to-an-earlier-commit-on-a-repo/65735/2) to a previous commit (after installing git lfs)

```
# git lfs install
GIT_LFS_SKIP_SMUDGE=1 git clone https://huggingface.co/datasets/USER/REPO
cd REPO
git reset --hard HASH
git push --force
```
Make convert_to_parquet CLI command create script branch
State: closed | Author: albertvillanova (MEMBER)
Labels: name: enhancement

As proposed by @severo, maybe we should add this functionality as well to the CLI command to convert a script-dataset to Parquet. See: https://github.com/huggingface/datasets/pull/6795#discussion_r1562819168
> When providing support, we sometimes suggest that users store their script in a script branch. What do you think of this alternative to deleting the files?
got fileNotFound
State: closed | Author: laoniandisko (NONE)

### Describe the bug

When I use load_dataset to load the nyanko7/danbooru2023 data set, the cache is read in the form of a symlink. There may be a problem with the arrow_dataset initialization process and I get FileNotFoundError: [Errno 2] No such file or directory: '2945000.jpg'

### Steps to reproduce the bug

#code show as below
from datasets import load_dataset
data = load_dataset("nyanko7/danbooru2023",cache_dir=<symlink>)
data["train"][0]

### Expected behavior

I should get this result:
{'image': <PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=365x256 at 0x7FB730CB4070>, 'label': 0}

### Environment info

datasets==2.12.0
python==3.10.14


Comments: Hi! I'll open a PR on the Hub to fix this, but please use the Hub's [Community tab](https://huggingface.co/datasets/nyanko7/danbooru2023/discussions) to report such issues in the future.

I've opened a [PR](https://huggingface.co/datasets/nyanko7/danbooru2023/discussions/8) in the repo, so let's continue the discussion there
`DatasetBuilder._split_generators` incomplete type annotation
State: closed | Author: JonasLoos (CONTRIBUTOR)

### Describe the bug

The [`DatasetBuilder._split_generators`](https://github.com/huggingface/datasets/blob/0f27d7b77c73412cfc50b24354bfd7a3e838202f/src/datasets/builder.py#L1449) function has currently the following signature:

```python
class DatasetBuilder:
    def _split_generators(self, dl_manager: DownloadManager):
        ...
```

However, the `dl_manager` argument can also be of type [`StreamingDownloadManager`](https://github.com/huggingface/datasets/blob/0f27d7b77c73412cfc50b24354bfd7a3e838202f/src/datasets/download/streaming_download_manager.py#L962), which has different functionality. For example, the `download` function doesn't download, but rather just returns the given url(s). 

I suggest changing the function signature to:

```python
class DatasetBuilder:
    def _split_generators(self, dl_manager: Union[DownloadManager, StreamingDownloadManager]):
        ...
```

and also adjust the docstring accordingly.

I would like to create a Pull Request to fix this, and have the following questions:
* Are there also other options than `DownloadManager`, and `StreamingDownloadManager`?
* Should this also be changed in other functions?

### Steps to reproduce the bug

Minimal example to print the different class names:

```python
import tempfile
from datasets import load_dataset

example = b'''
from datasets import GeneratorBasedBuilder, DatasetInfo, Features, Value, SplitGenerator

class Test(GeneratorBasedBuilder):
    def _info(self):
        return DatasetInfo(features=Features({"x": Value("int64")}))
    def _split_generators(self, dl_manager):
        print(type(dl_manager))
        return [SplitGenerator('test')]
    def _generate_examples(self):
        yield 0, {'x': 42}
'''

with tempfile.NamedTemporaryFile(suffix='.py') as f:
    f.write(example)
    f.flush()
    load_dataset(f.name, streaming=False)
    load_dataset(f.name, streaming=True)
```

### Expected behavior

complete type annotations

### Environment info

/

Comments: Good catch! Feel free to open a PR with the suggested fix :).

There is also the [`MockDownloadManager`](https://github.com/JonasLoos/datasets/blob/main/src/datasets/download/mock_download_manager.py#L33), which seems like it might get passed here too. However, to me, it doesn't really seem relevant to the users of the datasets library, so I would just ignore it. What do you think, @mariosasko?

The API (`dummy_data` CLI command ) that uses the `MockDownloadManager` has been deprecated, so ignoring it sounds good!
Fix CI test_load_dataset_distributed_with_script
State: closed | Author: albertvillanova (MEMBER)

Fix #6796.

Comments: The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6797). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

Finally:
- the initial issue seems it was temporary
- there is a different issue now 

```
FAILED tests/test_load.py::ModuleFactoryTest::test_HubDatasetModuleFactoryWithParquetExport - datasets.utils._dataset_viewer.DatasetViewerError: No exported Parquet files available.
FAILED tests/test_load.py::ModuleFactoryTest::test_HubDatasetModuleFactoryWithParquetExport_errors_on_wrong_sha - datasets.utils._dataset_viewer.DatasetViewerError: No exported Parquet files available.
FAILED tests/test_load.py::test_load_dataset_builder_for_community_dataset_with_script - AssertionError: assert 'dataset_with_script' == 'parquet'
  
  - parquet
  + dataset_with_script
```
CI is broken due to hf-internal-testing/dataset_with_script
State: closed | Author: albertvillanova (MEMBER)
Labels: name: bug

CI is broken for test_load_dataset_distributed_with_script. See: https://github.com/huggingface/datasets/actions/runs/8614926216/job/23609378127
```
FAILED tests/test_load.py::test_load_dataset_distributed_with_script[None] - assert False
 +  where False = all(<generator object test_load_dataset_distributed_with_script.<locals>.<genexpr> at 0x7f0c741de3b0>)
FAILED tests/test_load.py::test_load_dataset_distributed_with_script[force_redownload] - assert False
 +  where False = all(<generator object test_load_dataset_distributed_with_script.<locals>.<genexpr> at 0x7f0be45f6ea0>)
```

Comments: Finally:
- the initial issue seems it was temporary
- there is a different issue now: https://github.com/huggingface/datasets/actions/runs/8627153993/job/23646584590?pr=6797
```
FAILED tests/test_load.py::ModuleFactoryTest::test_HubDatasetModuleFactoryWithParquetExport - datasets.utils._dataset_viewer.DatasetViewerError: No exported Parquet files available.
FAILED tests/test_load.py::ModuleFactoryTest::test_HubDatasetModuleFactoryWithParquetExport_errors_on_wrong_sha - datasets.utils._dataset_viewer.DatasetViewerError: No exported Parquet files available.
FAILED tests/test_load.py::test_load_dataset_builder_for_community_dataset_with_script - AssertionError: assert 'dataset_with_script' == 'parquet'
  
  - parquet
  + dataset_with_script
```

Maybe related to `hf-internal-testing/dataset_with_script` dataset: https://huggingface.co/datasets/hf-internal-testing/dataset_with_script

This URL: https://datasets-server.huggingface.co/parquet?dataset=hf-internal-testing/dataset_with_script
raises:
> {"error":"The dataset viewer doesn't support this dataset because it runs arbitrary python code. Please open a discussion in the discussion tab if you think this is an error and tag @lhoestq and @severo."}

Was there a recent change on the Hub enforcing this behavior?

OK, I just saw this PR:
- https://github.com/huggingface/dataset-viewer/pull/2689

Once merged and deployed, it should fix the issue.

Once the script-dataset has been allowed in the dataset-viewer, we should fix our test to make the CI pass.

I am addressing this.
Loading just one particular split is not possible for imagenet-1k
State: open | Author: PaulPSta (NONE)

### Describe the bug

I'd expect the following code to download just the validation split but instead I get all data on my disk (train, test and validation splits)

`
from datasets import load_dataset

dataset = load_dataset("imagenet-1k", split="validation", trust_remote_code=True)
`

Is it expected to work like that? 

### Steps to reproduce the bug

1. Install the required libraries (python, datasets, huggingface_hub)
2. Login using huggingface cli
2. Run the code in the description

### Expected behavior

Just a single (validation) split should be downloaded.

### Environment info

python: 3.12.2
datasets: 2.18.0
huggingface_hub: 0.22.2

Comments: +1
`add_faiss_index` raises ValueError: not enough values to unpack (expected 2, got 1)
State: closed | Author: NeuralFlux (NONE)

### Describe the bug

Calling `add_faiss_index` on a `Dataset` with a column argument raises a ValueError. The following is the trace

```python
    214 def replacement_add(self, x):
    215     """Adds vectors to the index.
    216     The index must be trained before vectors can be added to it.
    217     The vectors are implicitly numbered in sequence. When `n` vectors are
   (...)
    224         `dtype` must be float32.
    225     """
--> 227     n, d = x.shape
    228     assert d == self.d
    229     x = np.ascontiguousarray(x, dtype='float32')

ValueError: not enough values to unpack (expected 2, got 1)
```

### Steps to reproduce the bug

1. Load any dataset like `ds = datasets.load_dataset("wikimedia/wikipedia", "20231101.en")["train"]`
2. Add an FAISS index on any column `ds.add_faiss_index('title')`

### Expected behavior

The index should be created

### Environment info

- `datasets` version: 2.18.0
- Platform: Linux-6.5.0-26-generic-x86_64-with-glibc2.35
- Python version: 3.9.19
- `huggingface_hub` version: 0.22.2
- PyArrow version: 15.0.2
- Pandas version: 2.2.1
- `fsspec` version: 2024.2.0
- `faiss-cpu` version: 1.8.0

Comments: I realized I was passing a string column to this instead of float. Is it possible to add a warning or error to prevent users from falsely believing there's a bug?

Hello!

I agree that we could add some safeguards around the type of `ds[column]`. At least for FAISS, we need the column to be made of embeddings as FAISS doesn't perform the embeddings itself.

I can propose a PR sometime this week.

@Dref360 thanks for the initiative!
A Question About the Map Function
State: closed | Author: onlyonlysong (NONE)

### Describe the bug

Hello,

I have a question regarding the map function in the Hugging Face datasets.

The situation is as follows: when I load a jsonl file using load_dataset(..., streaming=False), and then utilize the map function to process it, I specify that the returned example should be of type Torch.tensor. However, I noticed that after applying the map function, the datatype automatically changes to List, which leads to errors in my program.

I attempted to use load_dataset(..., streaming=True), and this issue no longer occurs. I'm not entirely clear on why this happens. Could you please provide some insights into this?

### Steps to reproduce the bug

1.dataset =  load_dataset(xxx, streaming = False)
2. dataset.map(function), function will return torch.Tensor.
3. you will find the format of data in dataset is List.

### Expected behavior

I expected to receieve the format of data is torch.Tensor.

### Environment info

2.18.0

Comments: All data is saved in the arrow format on disk.
If you return a tensor it gets converted to arrow before saving to disk when using map.

To get a tensor when you access data elements you can use `dataset.set_format("pt")`.
Note that this just changes how the data is loaded, not how it is stored.

> All data is saved in the arrow format on disk. If you return a tensor it gets converted to arrow before saving to disk when using map.
> 
> To get a tensor when you access data elements you can use `dataset.set_format("pt")`. Note that this just changes how the data is loaded, not how it is stored.

Thank you very much for your explanation, I understand what you mean now. So you're saying that when streaming=True, there's no need to convert it to the arrow format and save it to disk. But if we directly load all formats and then convert them into the arrow format after passing through the map function, it will convert torch.Tensor into a List. I see.
Remove get_inferred_type from ArrowWriter write_batch
State: closed | Author: Modexus (CONTRIBUTOR)

Inferring the type seems to be unnecessary given that the pyarrow array has already been created.
Because pyarrow array creation is sometimes extremely slow this doubles the time write_batch takes.

Comments: The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6781). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

Close in favor of #6786.
Dataset.to_csv() missing commas in columns with lists
State: open | Author: mpickard-dataprof (NONE)

### Describe the bug

The `to_csv()` method does not output commas in lists.  So when the Dataset is loaded back in the data structure of the column with a list is not correct.

Here's an example:

Obviously, it's not as trivial as inserting commas in the list, since its a comma-separated file.  But hopefully there's a way to export the list in a way that it'll be imported by `load_dataset()` correctly.

### Steps to reproduce the bug

Here's some code to reproduce the bug:


```python
from datasets import Dataset

ds = Dataset.from_dict(
    {
        "pokemon": ["bulbasaur", "squirtle"],
        "type": ["grass", "water"]
    }
)

def ascii_to_hex(text):
    return [ord(c) for c in text]

ds = ds.map(lambda x: {"int": ascii_to_hex(x['pokemon'])})

ds.to_csv('../output/temp.csv')
```

temp.csv then contains:
```

### Expected behavior

ACTUAL OUTPUT:
```
pokemon,type,int
bulbasaur,grass,[ 98 117 108  98  97 115  97 117 114]
squirtle,water,[115 113 117 105 114 116 108 101]
```

EXPECTED OUTPUT:
```
pokemon,type,int
bulbasaur,grass,[98, 117, 108,  98,  97, 115,  97, 117, 114]
squirtle,water,[115, 113, 117, 105, 114, 116, 108, 101]
```

or probably something more like this since it's a CSV file:
```
pokemon,type,int
bulbasaur,grass,"[98, 117, 108,  98,  97, 115,  97, 117, 114]"
squirtle,water,"[115, 113, 117, 105, 114, 116, 108, 101]"
```

### Environment info

### Package Version
Name: datasets
Version: 2.16.1

### Python
version: 3.10.12


### OS Info
PRETTY_NAME="Ubuntu 22.04.4 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.4 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
...
UBUNTU_CODENAME=jammy

Comments: Hello!

This is due to how pandas write numpy arrays to csv. [Source](https://stackoverflow.com/questions/54753179/to-csv-saves-np-array-as-string-instead-of-as-a-list)
To fix this, you can convert them to list yourselves.

```python
df = ds.to_pandas()
df['int'] = df['int'].apply(lambda arr: list(arr))
df.to_csv(index=False, '../output/temp.csv')
```

I think it would be good if `datasets` would do the conversion itself, but it's a breaking change and I would wait for the greenlight from someone from HF.
Generating split is very slow when Image format is PNG
State: open | Author: Tramac (NONE)

### Describe the bug

When I create a dataset, it gets stuck while generating cached data. 
The image format is PNG, and it will not get stuck when the image format is jpeg.

![image](https://github.com/huggingface/datasets/assets/22740819/3b888fd8-e6d6-488f-b828-95a8f206a152)

After debugging, I know that it is because of the `pa.array` operation in [arrow_writer](https://github.com/huggingface/datasets/blob/2.13.0/src/datasets/arrow_writer.py#L553), but i don't why.

### Steps to reproduce the bug

```
from datasets import Dataset

def generator(lines):
    for line in lines:
        img = Image.open(open(line["url"], "rb"))
        # print(img.format)  # "PNG"
        yield {
            "image": img,
        }

lines = open(dataset_path, "r")
dataset = Dataset.from_generator(
    generator,
    gen_kwargs={"lines": lines}
)
```

### Expected behavior

Generating split done.

### Environment info

datasets    2.13.0

Comments: I think this is due to the speed of reading a `png` image using pillow compared to a `jpg` image.
Notably the same is true with `tiff`, it is even faster than `jpg` in my case.
(Willing to PR) Datasets with custom python objects
State: open | Author: fzyzcjy (CONTRIBUTOR)
Labels: name: enhancement

### Feature request

Hi thanks for the library! I would like to have a huggingface Dataset, and one of its column is custom (non-serializable) Python objects. For example, a minimal code:

```
class MyClass:
    pass

dataset = datasets.Dataset.from_list([
    dict(a=MyClass(), b='hello'),
])
```

It gives error:

```
ArrowInvalid: Could not convert <__main__.MyClass object at 0x7a852830d050> with type MyClass: did not recognize Python value type when inferring an Arrow data type
```

I guess it is because Dataset forces to convert everything into arrow format. However, is there any ways to make the scenario work? Thanks!

### Motivation

(see above)

### Your contribution

Yes, I am happy to PR!

Cross-posted: https://discuss.huggingface.co/t/datasets-with-custom-python-objects/79050?u=fzyzcjy

EDIT: possibly related https://github.com/huggingface/datasets/issues/5766
Compatibility issue between s3fs, fsspec, and datasets
State: closed | Author: njbrake (NONE)

### Describe the bug

Here is the full error stack when installing:

```
ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
datasets 2.18.0 requires fsspec[http]<=2024.2.0,>=2023.1.0, but you have fsspec 2024.3.1 which is incompatible.
Successfully installed aiobotocore-2.12.1 aioitertools-0.11.0 botocore-1.34.51 fsspec-2024.3.1 jmespath-1.0.1 s3fs-2024.3.1 urllib3-2.0.7 wrapt-1.16.0
```
When I install with pip, pip allows this error to exist while still installing s3fs, but this error breaks poetry, since poetry will refuse to install s3fs because of the dependency conflict.

Maybe I'm missing something so maybe it's not a bug but some mistake on my end? Any input would be helpful. Thanks!

### Steps to reproduce the bug

1. conda create -n tmp python=3.10 -y
2. conda activate tmp
3. pip install datasets
4. pip install s3fs

### Expected behavior

I would expect there to be no error.

### Environment info

MacOS (ARM), Python3.10, conda 23.11.0. 

Comments: Hi! Instead of running `pip install` separately for each package, you should pass all the packages to a single `pip install` call (in this case, `pip install datasets s3fs`) to let `pip` properly resolve their versions.

> Hi! Instead of running `pip install` separately for each package, you should pass all the packages to a single `pip install` call (in this case, `pip install datasets s3fs`) to let `pip` properly resolve their versions.

Thanks so much! My inexperience with pip is showing 😆  🙈 

> Hi! Instead of running `pip install` separately for each package, you should pass all the packages to a single `pip install` call (in this case, `pip install datasets s3fs`) to let `pip` properly resolve their versions.

you are awesome bro

Hey, the suggestion by @mariosasko unfortunately only address this issue via pip. The original message was about poetry and I am still facing a dependency conflict with that.

The following command complains first about `fsspec` (`... no versions of fsspec match ...`) and then I get an error.

Command:
`poetry add datasets s3fs` 

Error: 
` ... your project ... depends on both datasets (^3.1.0) and s3fs (^2024.10.0), version solving failed`

Installing first `s3fs` and then the rest of the huggingface libraries, like `datasets`, also did not help.