Sulak2020/github-issues-multirepo-datasets-Sulakshana huggingface dataset:
Title: Add R as a How to use from the Polars (R) Library as an option
State: open
Labels: name: enhancement
description: New feature or request

### Feature request

The boiler plate code to access a dataset via the hugging face file system is very useful. Please addd 


## Add Polars (R) option
The equivailent code works, because the [Polars-R](https://github.com/pola-rs/r-polars) wrapper has hugging faces funcitonaliy as well.

```r
library(polars)

df <- pl$read_parquet("hf://datasets/SALURBAL/core__admin_cube_public/core__admin_cube_public.parquet")
```

## Polars (python) option
![image](https://github.com/user-attachments/assets/8f1bcd19-e578-4b18-b324-7cc00b80ac0a)


## Libraries Currently

![image](https://github.com/user-attachments/assets/0cf50063-f9db-443c-97b4-3ef0664b6e6e)




### Motivation

There are many data/analysis/research/statistics teams (particularly in academia and pharma) that use R as the default language. R has great integration with most of the newer data techs (arrow, parquet, polars) and having this included could really help in bringing this community into the hugging faces ecosystem.

**This is a small/low-hanging-fruit front end change but would make a big impact expanding the community**

### Your contribution

I am not sure which repositroy this should be in, but I have experience in R, Python and JS and happy to submit a PR in the appropriate repository.
Title: Huggingface GIT returns null as Content-Type instead of application/x-git-receive-pack-result
State: open

### Describe the bug

We push changes to our datasets programmatically. Our git client jGit reports that the hf git server returns null as Content-Type after a push.

### Steps to reproduce the bug

A basic kotlin application:
```
   val person = PersonIdent(
        "padmalcom",
        "padmalcom@sth.com"
    )

    val cp = UsernamePasswordCredentialsProvider(
        "padmalcom",
        "mysecrettoken"
    )

    val git =
        KGit.cloneRepository {
            setURI("https://huggingface.co/datasets/sth/images")
            setTimeout(60)
            setProgressMonitor(TextProgressMonitor())
            setCredentialsProvider(cp)
        }

    FileOutputStream("./images/images.csv").apply { writeCsv(images) }
    git.add {
        addFilepattern("images.csv")
    }

    for (i in images) {
        FileUtils.copyFile(
            File("./files/${i.id}"),
            File("./images/${i.id + File(i.fileName).extension }")
        )
        git.add {
            addFilepattern("${i.id + File(i.fileName).extension }")
        }
    }

    val revCommit = git.commit {
        author = person
        message = "Uploading images at " + LocalDateTime.now()
            .format(DateTimeFormatter.ISO_DATE_TIME)
        setCredentialsProvider(cp)
    }

    val push = git.push {
        setCredentialsProvider(cp)
    }
```

### Expected behavior

The git server is expected to return the Content-Type _application/x-git-receive-pack-result_.

### Environment info

It is independent from the datasets library.
Title: Fallback to arrow defaults when loading dataset with custom features that aren't registered locally
State: open

### Describe the bug

Datasets allows users to create and register custom features.

However if datasets are then pushed to the hub, this means that anyone calling load_dataset without registering the custom Features in the same way as the dataset creator will get an error message.

It would be nice to offer a fallback in this case.

### Steps to reproduce the bug

```python
load_dataset("alex-hh/custom-features-example")
```
(Dataset creation process - must be run in separate session so that NewFeature isn't registered in session in which download is attempted:)

```python
from dataclasses import dataclass, field
import pyarrow as pa
from datasets.features.features import register_feature

from datasets import Dataset, Features, Value, load_dataset
from datasets import Feature

@dataclass
class NewFeature(Feature):
    _type: str = field(default="NewFeature", init=False, repr=False)
    def __call__(self):
        return pa.int32()

def examples_generator():
    for i in range(5):
        yield {"feature": i}

ds = Dataset.from_generator(examples_generator, features=Features(feature=NewFeature()))
ds.push_to_hub("alex-hh/custom-features-example")
register_feature(NewFeature, "NewFeature")
```



### Expected behavior

It would be nice, and offer greater extensibility, if there was some kind of graceful fallback mechanism in place for cases where user-defined features are stored in the dataset but not available locally.

### Environment info

3.0.2
Title: add CustomFeature base class to support user-defined features with encoding/decoding logic
State: closed

intended as fix for #7220 if this kind of extensibility is something that datasets is willing to support!


```python
from datasets.features.features import CustomFeature


class ListOfStrs(CustomFeature):
    requires_encoding = True
    def _encode_example(self, value):
        if isinstance(value, str):
            return [str]
        else:
            return value
feats = Features(strlist=ListOfStrs())
feats.encode_example({"strlist": "a"})["strlist"] == feats["strlist"].encode_example("a")
```

Comments: @lhoestq would you be open to supporting this kind of extensibility?I suggested a fix in https://github.com/huggingface/datasets/issues/7220 that would not necessarily require a parent class for custom features, lmk what you think
Title: Custom features not compatible with special encoding/decoding logic
State: open

### Describe the bug

It is possible to register custom features using datasets.features.features.register_feature (https://github.com/huggingface/datasets/pull/6727)

However such features are not compatible with Features.encode_example/decode_example if they require special encoding / decoding logic because encode_nested_example / decode_nested_example checks whether the feature is in a fixed list of encodable types:

https://github.com/huggingface/datasets/blob/16a121d7821a7691815a966270f577e2c503473f/src/datasets/features/features.py#L1349

This prevents the extensibility of features to complex cases

### Steps to reproduce the bug

```python
class ListOfStrs:
    def encode_example(self, value):
        if isinstance(value, str):
            return [str]
        else:
            return value
feats = Features(strlist=ListOfStrs())
assert feats.encode_example({"strlist": "a"})["strlist"] = feats["strlist"].encode_example("a")}
```

### Expected behavior

Registered feature types should be encoded based on some property of the feature (e.g. requires_encoding)?

### Environment info

3.0.2

Comments: I think you can fix this simply by replacing the line with hardcoded features with `hastattr(schema, "encode_example")` actually#7284
Title: ds.map(f, num_proc=10) is slower than df.apply
State: open

### Describe the bug

pandas columns: song_id, song_name
ds = Dataset.from_pandas(df)

def has_cover(song_name):
    if song_name is None or pd.isna(song_name):
        return False
    return 'cover' in song_name.lower()

df['has_cover'] = df.song_name.progress_apply(has_cover)
ds = ds.map(lambda x: {'has_cover': has_cover(x['song_name'])}, num_proc=10)

time cost: 
1. df.apply: 100%|██████████| 12500592/12500592 [00:13<00:00, 959825.47it/s]
2. ds.map: Map (num_proc=10):  31%
 3899028/12500592 [00:28<00:38, 222532.89 examples/s]

### Steps to reproduce the bug

pandas columns: song_id, song_name
ds = Dataset.from_pandas(df)

def has_cover(song_name):
    if song_name is None or pd.isna(song_name):
        return False
    return 'cover' in song_name.lower()

df['has_cover'] = df.song_name.progress_apply(has_cover)
ds = ds.map(lambda x: {'has_cover': has_cover(x['song_name'])}, num_proc=10)

### Expected behavior

ds.map is ~num_proc faster than df.apply

### Environment info

pandas: 2.2.2
datasets: 2.19.1

Comments: Hi ! `map()` reads all the columns and writes the resulting dataset with all the columns as well, while df.column_name.apply only reads and writes one column and does it in memory. So this is speed difference is actually expected.

Moreover using multiprocessing on a dataset that lives in memory (from_pandas uses the same in-memory data as the pandas DataFrame while load_dataset or from_generator load from disk) requires to copy the data to each subprocess which can also be slow. Data loaded from disk don't need to be copied though since they work as a form of shared memory thanks to memory mapping.

However you can make you map() call much faster by making it read and write only the column you want:

```python
has_cover_ds = ds.map(lambda song_name: {'has_cover': has_cover(song_name)}, input_columns=["song_name"], remove_columns=ds.column_names)  # outputs a dataset with 1 column
ds = ds.concatenate_datasets([ds, has_cover_ds], axis=1)
```

and if your dataset is loaded from disk you can pass num_proc=10 and get a nice speed up as well (no need to copy the data to subprocesses)Isn't there a way to do memory mapping with the in-memory dataset without saving it to disk?Maybe saving it to a memory-mapped filesystem? It'd be like a trick to make datasets save to "disk" but actually it's memory. But it feels like there should be a better "automatic" way provided by `datasets`.
Title: Iterable dataset map with explicit features causes slowdown for Sequence features
State: open

### Describe the bug

When performing map, it's nice to be able to pass the new feature type, and indeed required by interleave and concatenate datasets.

However, this can cause a major slowdown for certain types of array features due to the features being re-encoded.

This is separate to the slowdown reported in #7206 

### Steps to reproduce the bug

```
from datasets import Dataset, Features, Array3D, Sequence, Value
import numpy as np
import time
features=Features(**{"array0": Sequence(feature=Value("float32"), length=-1), "array1": Sequence(feature=Value("float32"), length=-1)})
dataset = Dataset.from_dict({f"array{i}": [np.zeros((x,), dtype=np.float32) for x in [5000,10000]*25] for i in range(2)}, features=features)
```

```
ds = dataset.to_iterable_dataset()
ds = ds.with_format("numpy").map(lambda x: x)
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
```
~1.5 s on main


```
ds = dataset.to_iterable_dataset()
ds = ds.with_format("numpy").map(lambda x: x, features=features)
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
```
~ 3 s on main

### Expected behavior

I'm not 100% sure whether passing new feature types to formatted outputs of map should be supported or not, but assuming it should, then there should be a cost-free way to specify the new feature type - knowing feature type is required by interleave_datasets and concatenate_datasets for example

### Environment info

3.0.2
Title: Formatted map + with_format(None) changes array dtype for iterable datasets
State: open

### Describe the bug

When applying with_format -> map -> with_format(None), array dtypes seem to change, even if features are passed 

### Steps to reproduce the bug

```python
features=Features(**{"array0": Array3D((None, 10, 10), dtype="float32")})
dataset = Dataset.from_dict({f"array0": [np.zeros((100,10,10), dtype=np.float32)]*25}, features=features)
ds = dataset.to_iterable_dataset().with_format("numpy").map(lambda x: x, features=features)
ex_0 = next(iter(ds))
ds = dataset.to_iterable_dataset().with_format("numpy").map(lambda x: x, features=features).with_format(None)
ex_1 = next(iter(ds))
assert ex_1["array0"].dtype == ex_0["array0"].dtype, f"{ex_1['array0'].dtype} {ex_0['array0'].dtype}"
```


### Expected behavior

Dtypes should be preserved.

### Environment info

3.0.2

Comments: possibly due to this logic:

```python
    def _arrow_array_to_numpy(self, pa_array: pa.Array) -> np.ndarray:
        if isinstance(pa_array, pa.ChunkedArray):
            if isinstance(pa_array.type, _ArrayXDExtensionType):
                # don't call to_pylist() to preserve dtype of the fixed-size array
                zero_copy_only = _is_zero_copy_only(pa_array.type.storage_dtype, unnest=True)
                array: List = [
                    row for chunk in pa_array.chunks for row in chunk.to_numpy(zero_copy_only=zero_copy_only)
                ]
            else:
                zero_copy_only = _is_zero_copy_only(pa_array.type) and all(
                    not _is_array_with_nulls(chunk) for chunk in pa_array.chunks
                )
                array: List = [
                    row for chunk in pa_array.chunks for row in chunk.to_numpy(zero_copy_only=zero_copy_only)
                ]
        else:
            if isinstance(pa_array.type, _ArrayXDExtensionType):
                # don't call to_pylist() to preserve dtype of the fixed-size array
                zero_copy_only = _is_zero_copy_only(pa_array.type.storage_dtype, unnest=True)
                array: List = pa_array.to_numpy(zero_copy_only=zero_copy_only)
            else:
                zero_copy_only = _is_zero_copy_only(pa_array.type) and not _is_array_with_nulls(pa_array)
                array: List = pa_array.to_numpy(zero_copy_only=zero_copy_only).tolist()
```
Title: Add with_rank to Dataset.from_generator
State: open
Labels: name: enhancement
description: New feature or request

### Feature request

Add `with_rank` to `Dataset.from_generator` similar to `Dataset.map` and `Dataset.filter`. 

### Motivation

As for `Dataset.map` and `Dataset.filter`, this is useful when creating cache files using multi-GPU, where the rank can be used to select GPU IDs. For now, rank can be added in the `gen_kwars` argument; however, this, in turn, includes the rank when computing the fingerprint.

### Your contribution

Added #7199 which passes rank based on the `job_id` set by `num_proc`.
Title: Windows do not supprot signal.alarm and singal.signal
State: open

### Describe the bug

signal.alarm and signal.signal are used in the load.py module, but these are not supported by Windows.

### Steps to reproduce the bug

 lighteval accelerate --model_args "pretrained=gpt2,trust_remote_code=True" --tasks "community|kinit_sts" --custom_tasks "community_tasks/kinit_evals.py" --output_dir "./evals"

### Expected behavior

proceed with input(..) method

### Environment info

Windows 11
Title: Describe only selected fields in README
State: open
Labels: name: enhancement
description: New feature or request

### Feature request

Hi Datasets team! 

Is it possible to add the ability to describe only selected fields of the dataset files in `README.md`? For example, I have this open dataset ([open-llm-leaderboard/results](https://huggingface.co/datasets/open-llm-leaderboard/results?row=0)) and I want to describe only some fields in order not to overcomplicate the Dataset Preview and filter out some fields 

### Motivation

The `Results` dataset for the Open LLM Leaderboard contains json files with a complex nested structure. I would like to add `README.md` there to use the SQL console, for example. But if I describe the structure of this dataset completely, it will overcomplicate the use of Dataset Preview and the total number of columns will exceed 50 

### Your contribution

I'm afraid I'm not familiar with the project structure, so I won't be able to open a PR, but I'll try to help with something else if possible
Title: Convert Array features to numpy arrays rather than lists by default
State: open
Labels: name: enhancement
description: New feature or request

### Feature request

It is currently quite easy to cause massive slowdowns when using datasets and not familiar with the underlying data conversions by e.g. making bad choices of formatting.

Would it be more user-friendly to set defaults that avoid this as much as possible? e.g. format Array features as numpy arrays rather than python lists

### Motivation

Default array formatting leads to slow performance: e.g.

```python
import numpy as np
from datasets import Dataset, Features, Array3D
features=Features(**{"array0": Array3D((None, 10, 10), dtype="float32"), "array1": Array3D((None,10,10), dtype="float32")})
dataset = Dataset.from_dict({f"array{i}": [np.zeros((x,10,10), dtype=np.float32) for x in [2000,1000]*25] for i in range(2)}, features=features)
```

```python
t0 = time.time()
for ex in ds:
   pass
t1 = time.time()
```
~1.4 s

```python
ds = dataset.to_iterable_dataset()
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
```
~10s

```python
ds = dataset.with_format("numpy")
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
```
~0.04s

```python
ds = dataset.to_iterable_dataset().with_format("numpy")
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
```
~0.04s

### Your contribution

May be able to contribute
Title: Preserve features in iterable dataset.filter
State: closed

Fixes example in #7208 - I'm not sure what other checks I should do? @lhoestq 

I also haven't thought hard about the concatenate / interleaving example iterables but think this might work assuming that features are either all identical or None?

Comments: Yes your assumption on concatenate/interleave is ok imo.

It seems the TypedExamplesIterable can slow down things, it should take formatting into account to not convert numpy arrays to python lists

right now it's slow (unrelatedly to your PR):

```python
>>> ds = Dataset.from_dict({"a": np.zeros((1000, 32, 32))}).to_iterable_dataset().with_format("np")
>>> filtered_ds = ds.filter(lambda x: True)
>>> %time sum(1 for _ in ds)
CPU times: user 175 ms, sys: 8.1 ms, total: 183 ms
Wall time: 184 ms
1000
>>> %time sum(1 for _ in filtered_ds)
CPU times: user 4.1 s, sys: 8.41 ms, total: 4.1 s
Wall time: 4.12 s
1000
```The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7209). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.> It seems the TypedExamplesIterable can slow down things, it should take formatting into account to not convert numpy arrays to python lists

Should be fixed by updated #7207 I hope!
Title: Iterable dataset.filter should not override features
State: closed

### Describe the bug

When calling filter on an iterable dataset, the features get set to None

### Steps to reproduce the bug

import numpy as np
import time
from datasets import Dataset, Features, Array3D

```python
features=Features(**{"array0": Array3D((None, 10, 10), dtype="float32"), "array1": Array3D((None,10,10), dtype="float32")})
dataset = Dataset.from_dict({f"array{i}": [np.zeros((x,10,10), dtype=np.float32) for x in [2000,1000]*25] for i in range(2)}, features=features)
ds = dataset.to_iterable_dataset()
orig_column_names = ds.column_names
ds = ds.filter(lambda x: True)
assert ds.column_names == orig_column_names
```

### Expected behavior

Filter should preserve features information

### Environment info

3.0.2

Comments: closed by https://github.com/huggingface/datasets/pull/7209, thanks @alex-hh !
Title: Slow iteration for iterable dataset with numpy formatting for array data
State: open

### Describe the bug

When working with large arrays, setting with_format to e.g. numpy then applying map causes a significant slowdown for iterable datasets.

### Steps to reproduce the bug

```python
import numpy as np
import time
from datasets import Dataset, Features, Array3D

features=Features(**{"array0": Array3D((None, 10, 10), dtype="float32"), "array1": Array3D((None,10,10), dtype="float32")})
dataset = Dataset.from_dict({f"array{i}": [np.zeros((x,10,10), dtype=np.float32) for x in [2000,1000]*25] for i in range(2)}, features=features)
```

Then
```python
ds = dataset.to_iterable_dataset()
ds = ds.with_format("numpy").map(lambda x: x)
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
print(t1-t0)
```

takes 27 s, whereas

```python
ds = dataset.to_iterable_dataset()
ds = ds.with_format("numpy")
ds = dataset.to_iterable_dataset()
t0 = time.time()
for ex in ds:
    pass
t1 = time.time()
print(t1 - t0)
```

takes ~1s

### Expected behavior

Map should not introduce a slowdown when formatting is enabled.

### Environment info

3.0.2

Comments: The below easily eats up 32G of RAM. Leaving it for a while bricked the laptop with 16GB.

```
dataset = load_dataset("Voxel51/OxfordFlowers102", data_dir="data").with_format("numpy")
processed_dataset = dataset.map(lambda x: x)
```

![image](https://github.com/user-attachments/assets/c1863a69-b18f-4014-89dc-98994336df96)

Similar problems occur if using a real transform function in `.map()`.
Title: fix ci benchmark
State: closed

we're not using the benchmarks anymore + they were not working anyway due to token permissions

I keep the code in case we ever want to re-run the benchmark manually

Comments: The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7205). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Title: fix unbatched arrow map for iterable datasets
State: closed

Fixes the bug when applying map to an arrow-formatted iterable dataset described here:

https://github.com/huggingface/datasets/issues/6833#issuecomment-2399903885

```python

from datasets import load_dataset
ds = load_dataset("rotten_tomatoes", split="train", streaming=True)
ds = ds.with_format("arrow").map(lambda x: x)
for ex in ds:
    pass
```

@lhoestq 

Comments: The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7204). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Title: `from_parquet` return type annotation
State: open

### Describe the bug

As already posted in https://github.com/microsoft/pylance-release/issues/6534, the correct type hinting fails when building a dataset using the `from_parquet` constructor.
Their suggestion is to comprehensively annotate the method's return type to better align with the docstring information.

### Steps to reproduce the bug

```python
from datasets import Dataset

dataset = Dataset.from_parquet(path_or_paths="file")
dataset.map(lambda x: {"new": x["old"]}, batched=True)
```

### Expected behavior

map is a [valid](https://huggingface.co/docs/datasets/v3.0.1/en/package_reference/main_classes#datasets.Dataset.map), no error should be thrown.

### Environment info

- `datasets` version: 3.0.1
- Platform: macOS-15.0.1-arm64-arm-64bit
- Python version: 3.12.6
- `huggingface_hub` version: 0.25.1
- PyArrow version: 17.0.0
- Pandas version: 2.2.3
- `fsspec` version: 2024.6.1