Kokolipa/github-issues huggingface dataset:
Issue: Datasets keeps rebuilding the dataset every time i call the python script
State: open

### Describe the bug

Every time it runs, somehow, samples increase.
This can cause a 12mb dataset to have other built versions of 400 mbs+

<img width="363" height="481" alt="Image" src="https://github.com/user-attachments/assets/766ce958-bd2b-41bc-b950-86710259bfdc" />

### Steps to reproduce the bug


`from datasets import load_dataset
s = load_dataset('~/.cache/huggingface/datasets/databricks___databricks-dolly-15k')['train']
`
1. A dataset needs to be available in the .cache folder
2. Run the code multiple times, and every time it runs, more versions are created


### Expected behavior

The number of samples increases every time the script runs

### Environment info

- `datasets` version: 3.6.0
- Platform: Windows-11-10.0.26100-SP0
- Python version: 3.13.3
- `huggingface_hub` version: 0.32.3
- PyArrow version: 20.0.0
- Pandas version: 2.2.3
- `fsspec` version: 2025.3.0


here is the code to load the dataset form the cache:

```python
s = load_dataset('databricks/databricks-dolly-15k')['train']
```

if you pass the location of a local directory it will create a new cache based on that directory content
Issue: Probabilistic High Memory Usage and Freeze on Python 3.10
State: open

### Describe the bug

A probabilistic issue encountered when processing datasets containing PIL.Image columns using the huggingface/datasets library on Python 3.10. The process occasionally experiences a sudden and significant memory spike, reaching 100% utilization, leading to a complete freeze. During this freeze, the process becomes unresponsive, cannot be forcefully terminated, and does not throw any exceptions.

I have attempted to mitigate this issue by setting `datasets.config.IN_MEMORY_MAX_SIZE`, but it had no effect. In fact, based on the document of `load_dataset`, I suspect that setting `IN_MEMORY_MAX_SIZE` might even have a counterproductive effect.

This bug is not consistently reproducible, but its occurrence rate significantly decreases or disappears entirely when upgrading Python to version 3.11 or higher. Therefore, this issue also serves to share a potential solution for others who might encounter similar problems.

### Steps to reproduce the bug

Due to the probabilistic nature of this bug, consistent reproduction cannot be guaranteed for every run. However, in my environment, processing large datasets like timm/imagenet-1k-wds(whether reading, casting, or mapping operations) almost certainly triggers the issue at some point.
The probability of the issue occurring drastically increases when num_proc is set to a value greater than 1 during operations.

When the issue occurs, my system logs repeatedly show the following warnings:
```
WARN: very high memory utilization: 57.74GiB / 57.74GiB (100 %)
WARN: container is unhealthy: triggered memory limits (OOM)
WARN: container is unhealthy: triggered memory limits (OOM)
WARN: container is unhealthy: triggered memory limits (OOM)
```

### Expected behavior

The dataset should be read and processed normally without memory exhaustion or freezing. If an unrecoverable error occurs, an appropriate exception should be raised.

I have found that upgrading Python to version 3.11 or above completely resolves this issue. On Python 3.11, when memory usage approaches 100%, it suddenly drops before slowly increasing again. I suspect this behavior is due to an expected memory management action, possibly involving writing to disk cache, which prevents the complete freeze observed in Python 3.10.

### Environment info

- `datasets` version: 4.0.0
- Platform: Linux-5.15.0-71-generic-x86_64-with-glibc2.35
- Python version: 3.10.12
- `huggingface_hub` version: 0.33.4
- PyArrow version: 20.0.0
- Pandas version: 2.3.1
- `fsspec` version: 2025.3.0
Issue: metric glue breaks with 4.0.0
State: closed

### Describe the bug

worked fine with 3.6.0, and with 4.0.0 `eval_metric = metric.compute()` in HF Accelerate breaks.

The code that fails is:
https://huggingface.co/spaces/evaluate-metric/glue/blob/v0.4.0/glue.py#L84

```
def simple_accuracy(preds, labels):
    print(preds, labels)
    print(f"{preds==labels}")
    return float((preds == labels).mean())
```
data:
```
Column([1, 0, 0, 1, 1]) Column([1, 0, 0, 1, 0])
False
```

```
[rank0]:     return float((preds == labels).mean())
[rank0]:                  ^^^^^^^^^^^^^^^^^^^^^^
[rank0]: AttributeError: 'bool' object has no attribute 'mean'
```

Some behavior has changed in this new major release of `datasets` and requires updating HF accelerate and perhaps the glue metric code, all belong to HF.

### Environment info

datasets=4.0.0

I released `evaluate` 0.4.5 yesterday to fix the issue - sorry for the inconvenience:

```
pip install -U evaluate
```

Thanks so much, @lhoestq!
Issue: To support decoding audio data, please install 'torchcodec'.
State: closed


In the latest version of datasets==4.0.0, i cannot print the audio data on the Colab notebook. But it works on the 3.6.0 version.

!pip install -q -U datasets huggingface_hub fsspec

from datasets import load_dataset

downloaded_dataset = load_dataset("ymoslem/MediaSpeech", "tr", split="train")
print(downloaded_dataset["audio"][0])

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
[/tmp/ipython-input-4-90623240.py](https://localhost:8080/#) in <cell line: 0>()
----> 1 downloaded_dataset["audio"][0]

10 frames
[/usr/local/lib/python3.11/dist-packages/datasets/features/audio.py](https://localhost:8080/#) in decode_example(self, value, token_per_repo_id)
    170             from ._torchcodec import AudioDecoder
    171         else:
--> 172             raise ImportError("To support decoding audio data, please install 'torchcodec'.")
    173 
    174         if not self.decode:

ImportError: To support decoding audio data, please install 'torchcodec'. 

### Environment info

- `datasets` version: 4.0.0
- Platform: Linux-6.1.123+-x86_64-with-glibc2.35
- Python version: 3.11.13
- `huggingface_hub` version: 0.33.2
- PyArrow version: 18.1.0
- Pandas version: 2.2.2
- `fsspec` version: 2025.3.0

Hi ! yes you should `!pip install -U datasets[audio]` to have the required dependencies.

`datasets` 4.0 now relies on `torchcodec` for audio decoding. The `torchcodec` AudioDecoder enables streaming from HF and also allows to decode ranges of audio

Same issues on Colab.

> !pip install -U datasets[audio] 

This works for me. Thanks.
Issue: Toxicity fails with datasets 4.0.0
State: closed

### Describe the bug

With the latest 4.0.0 release, huggingface toxicity evaluation module fails with error: `ValueError: text input must be of type `str` (single example), `List[str]` (batch or single pretokenized example) or `List[List[str]]` (batch of pretokenized examples).`

### Steps to reproduce the bug

Repro:
```
>>> toxicity.compute(predictions=["This is a response"])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/evaluate/module.py", line 467, in compute
    output = self._compute(**inputs, **compute_kwargs)
  File "/Users/serena.ruan/.cache/huggingface/modules/evaluate_modules/metrics/evaluate-measurement--toxicity/2390290fa0bf6d78480143547c6b08f3d4f8805b249df8c7a8e80d0ce8e3778b/toxicity.py", line 135, in _compute
    scores = toxicity(predictions, self.toxic_classifier, toxic_label)
  File "/Users/serena.ruan/.cache/huggingface/modules/evaluate_modules/metrics/evaluate-measurement--toxicity/2390290fa0bf6d78480143547c6b08f3d4f8805b249df8c7a8e80d0ce8e3778b/toxicity.py", line 103, in toxicity
    for pred_toxic in toxic_classifier(preds):
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/pipelines/text_classification.py", line 159, in __call__
    result = super().__call__(*inputs, **kwargs)
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/pipelines/base.py", line 1431, in __call__
    return self.run_single(inputs, preprocess_params, forward_params, postprocess_params)
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/pipelines/base.py", line 1437, in run_single
    model_inputs = self.preprocess(inputs, **preprocess_params)
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/pipelines/text_classification.py", line 183, in preprocess
    return self.tokenizer(inputs, return_tensors=return_tensors, **tokenizer_kwargs)
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/tokenization_utils_base.py", line 2867, in __call__
    encodings = self._call_one(text=text, text_pair=text_pair, **all_kwargs)
  File "/Users/serena.ruan/miniconda3/envs/mlflow-310/lib/python3.10/site-packages/transformers/tokenization_utils_base.py", line 2927, in _call_one
    raise ValueError(
ValueError: text input must be of type `str` (single example), `List[str]` (batch or single pretokenized example) or `List[List[str]]` (batch of pretokenized examples).
```

### Expected behavior

This works before 4.0.0 release

### Environment info

- `datasets` version: 4.0.0
- Platform: macOS-15.5-arm64-arm-64bit
- Python version: 3.10.16
- `huggingface_hub` version: 0.33.0
- PyArrow version: 19.0.1
- Pandas version: 2.2.3
- `fsspec` version: 2024.12.0

Hi ! You can fix this by upgrading `evaluate`:

```
pip install -U evaluate
```

Thanks, verified evaluate 0.4.5 works!
Issue: Mapping function not working if the first example is returned as None
State: closed

### Describe the bug

https://github.com/huggingface/datasets/blob/8a19de052e3d79f79cea26821454bbcf0e9dcd68/src/datasets/arrow_dataset.py#L3652C29-L3652C37

Here we can see the writer is initialized on `i==0`. However, there can be cases where in the user mapping function, the first example is filtered out (length constraints, etc).

In this case, the writer would be a `None` type and the code will report `NoneType has no write function`.

A simple fix is available, simply change line 3652 from `if i == 0:` to `if writer is None:`

### Steps to reproduce the bug

Prepare a dataset

have this function

```
import datasets


def make_map_fn(split, max_prompt_tokens=3):
    def process_fn(example, idx):

        question = example['question']
        reasoning_steps = example['reasoning_steps']
        label = example['label']

        answer_format = ""
        for i in range(len(reasoning_steps)):
            system_message = "Dummy"

        all_steps_formatted = []

        content = f"""Dummy"""

        prompt = [
            {"role": "system", "content": system_message},
            {"role": "user", "content": content},
        ]
        tokenized = tokenizer.apply_chat_template(prompt, return_tensors="pt", truncation=False)
        if tokenized.shape[1] > max_prompt_tokens:
            return None  # skip overly long examples

        data = {
            "dummy": "dummy"
        }

        return data

    return process_fn

...
# load your dataset
...
train = train.map(function=make_map_fn('train'), with_indices=True)
```

### Expected behavior

The dataset mapping shall behave even when the first example is filtered out.

### Environment info

I am using `datasets==3.6.0` but I have observed this issue in the github repo too: https://github.com/huggingface/datasets/blob/8a19de052e3d79f79cea26821454bbcf0e9dcd68/src/datasets/arrow_dataset.py#L3652C29-L3652C37

Hi, map() always expect an output.

If you wish to filter examples, you should use filter(), in your case it could be something like this:

```python
ds = ds.map(my_processing_function).filter(ignore_long_prompts)
```

Realized this! Thanks a lot, I will close this issue then.
Issue: How can I add my custom data to huggingface datasets
State: open

I want to add my custom dataset in huggingface dataset. Please guide me how to achieve that.

Hey @xiagod 

The easiest way to add your custom data to Hugging Face Datasets is to use the built-in load_dataset function with your local files. Some examples include:

CSV files:
from datasets import load_dataset
dataset = load_dataset("csv", data_files="my_file.csv")

JSON or JSONL files:
from datasets import load_dataset
dataset = load_dataset("json", data_files="my_file.json")


Images stored in folders (e.g. data/train/cat/, data/train/dog/):
from datasets import load_dataset
dataset = load_dataset("imagefolder", data_dir="/path/to/pokemon")


These methods let you quickly create a custom dataset without needing to write a full script.

More information can be found in Hugging Face's tutorial "Create a dataset" or "Load" documentation here: 

https://huggingface.co/docs/datasets/create_dataset 

https://huggingface.co/docs/datasets/loading#local-and-remote-files



If you want to submit your dataset to the Hugging Face Datasets GitHub repo so others can load it follow this guide: 

https://huggingface.co/docs/datasets/upload_dataset
Issue: Broken EXIF crash the whole program
State: open

### Describe the bug

When parsing this image in the ImageNet1K dataset, the `datasets` crashs whole training process just because unable to parse an invalid EXIF tag.
![Image](https://github.com/user-attachments/assets/3c840203-ac8c-41a0-9cf7-45f64488037d)

### Steps to reproduce the bug

Use the `datasets.Image.decode_example` method to decode the aforementioned image could reproduce the bug.
The decoding function will throw an unhandled exception at the `image.getexif()` method call due to invalid utf-8 stream in EXIF tags.
```
File lib/python3.12/site-packages/datasets/features/image.py:188, in Image.decode_example(self, value, token_per_repo_id)
    186     image = PIL.Image.open(BytesIO(bytes_))
    187 image.load()  # to avoid "Too many open files" errors
--> 188 if image.getexif().get(PIL.Image.ExifTags.Base.Orientation) is not None:
    189     image = PIL.ImageOps.exif_transpose(image)
    190 if self.mode and self.mode != image.mode:

File lib/python3.12/site-packages/PIL/Image.py:1542, in Image.getexif(self)
   1540 xmp_tags = self.info.get("XML:com.adobe.xmp")
   1541 if not xmp_tags and (xmp_tags := self.info.get("xmp")):
-> 1542     xmp_tags = xmp_tags.decode("utf-8")
   1543 if xmp_tags:
   1544     match = re.search(r'tiff:Orientation(="|>)([0-9])', xmp_tags)

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa8 in position 4312: invalid start byte
```

### Expected behavior

The invalid EXIF tag should simply be ignored or issue a warning message, instead of crash the whole program at once.

### Environment info

- `datasets` version: 3.6.0
- Platform: Linux-6.5.0-18-generic-x86_64-with-glibc2.35
- Python version: 3.12.11
- `huggingface_hub` version: 0.33.0
- PyArrow version: 20.0.0
- Pandas version: 2.3.0
- `fsspec` version: 2025.3.0

There are other discussions about error handling for images decoding here : https://github.com/huggingface/datasets/issues/7632 https://github.com/huggingface/datasets/issues/7612

and a PR here: https://github.com/huggingface/datasets/pull/7638 (would love your input on the proposed solution !)
Issue: Function load_dataset() misinterprets string field content as part of dataset schema when dealing with `.jsonl` files
State: closed

### Describe the bug

When loading a `.jsonl` file using `load_dataset("json", data_files="data.jsonl", split="train")`, the function misinterprets the content of a string field  as if it were part of the dataset schema. 

In my case there is a field `body:` with a string value 
```
"### Describe the bug (...) ,action: string, datetime: timestamp[s], author: string, (...) Pandas version: 1.3.4"
```
As a result, I got an exception 
```
"TypeError: Couldn't cast array of type timestamp[s] to null". 
```
Full stack-trace in the attached file below.

I also attach a minimized dataset (data.json, a single entry) that reproduces the error.

**Observations**(on the minimal example): 
- if I remove _all fields before_ `body`, a different error appears,
- if I remove _all fields after_ `body`, yet another error appears,
- if `body` is _the only field_, the error disappears.

So this might be one complex bug or several edge cases interacting. I haven’t dug deeper.

Also changing the file extension to `.json` or `.txt` avoids the problem. This suggests **a possible workaround** for the general case: convert `.jsonl` to `.json`. Though I haven’t verified correctness of that workaround yet.

Anyway my understanding is that `load_dataset` with first argument set to "json" should properly handle `.jsonl` files. Correct me if I'm wrong.

[stack_trace.txt](https://github.com/user-attachments/files/21004153/stack_trace.txt)
[data.json](https://github.com/user-attachments/files/21004164/data.json)

P.S.
I discovered this while going through the HuggingFace tutorial. Specifically [this part](https://huggingface.co/learn/llm-course/chapter5/5?fw=pt).I will try to inform the tutorial team about this issue, as it can be a showstopper for young 🤗 adepts.

### Steps to reproduce the bug

1. Download attached [data.json](https://github.com/user-attachments/files/21004164/data.json) file.
2. Run the following code which should work correctly:
```
from datasets import load_dataset
load_dataset("json", data_files="data.json", split="train")
```
3. Change extension of the `data` file to `.jsonl` and run:
```
from datasets import load_dataset
load_dataset("json", data_files="data.jsonl", split="train")
```

This will trigger an error like the one in the attached [stack_trace.txt](https://github.com/user-attachments/files/21004153/stack_trace.txt).

One can also try removing fields before the `body` field and after it. These actions give different errors.


### Expected behavior

Parsing data in `.jsonl` format should yield the same result as parsing the same data in `.json` format. In any case, the content of a string field should never be interpreted as part of the dataset schema.

### Environment info

datasets version: _3.6.0_
pyarrow version: _20.0.0_
Python version: _3.11.9_
platform version: _macOS-15.5-arm64-arm-64bit_

Somehow I created the issue twice🙈 This one is an exact duplicate of #7664.
Issue: AttributeError: type object 'tqdm' has no attribute '_lock'
State: open

### Describe the bug

`AttributeError: type object 'tqdm' has no attribute '_lock'`

It occurs when I'm trying to load datasets in thread pool.

Issue https://github.com/huggingface/datasets/issues/6066 and PR https://github.com/huggingface/datasets/pull/6067 https://github.com/huggingface/datasets/pull/6068 tried to fix this. 


### Steps to reproduce the bug

Will have to try several times to reproduce the error because it is concerned with threads.
 
1. save some datasets for test
```pythonfrom datasets import Dataset, DatasetDict
import os

os.makedirs("test_dataset_shards", exist_ok=True)

for i in range(10):
    data = Dataset.from_dict({"text": [f"example {j}" for j in range(1000000)]})
    data = DatasetDict({'train': data})
    data.save_to_disk(f"test_dataset_shards/shard_{i}")
```

2. load them in a thread pool 
```python
from datasets import load_from_disk
from tqdm import tqdm
from concurrent.futures import ThreadPoolExecutor, as_completed
import glob

datas = glob.glob('test_dataset_shards/shard_*')
with ThreadPoolExecutor(max_workers=10) as pool:
    futures = [pool.submit(load_from_disk, it) for it in datas]
datas = []
for future in tqdm(as_completed(futures), total=len(futures)):
    datas.append(future.result())
```

### Expected behavior

no exception raised

### Environment info

datasets==2.19.0
python==3.10

Deleting a class (**not instance**) attribute might be invalid in this case, which is `tqdm` doing in `ensure_lock`.

```python
from tqdm import tqdm as old_tqdm

class tqdm1(old_tqdm):
     def __delattr__(self, attr):
        try:
            super().__delattr__(attr)
        except AttributeError:
            if attr != '_lock':
                print(attr)
                raise

class Meta(type):
    def __delattr__(cls, name):
        if name == "_lock":
            return  
        return super().__delattr__(name)
    
class tqdm2(old_tqdm, metaclass=Meta):
    pass

del tqdm2._lock
del tqdm1._lock # error
```

https://github.com/huggingface/datasets/blob/e71b0b19d79c7531f9b9bea7c09916b5f6157f42/src/datasets/utils/tqdm.py#L104-L122

A cheaper option (seems to work in my case):  
```python
from datasets import tqdm as hf_tqdm
hf_tqdm.set_lock(hf_tqdm.get_lock())
```
Issue: `load_dataset` defaults to json file format for datasets with 1 shard
State: open

### Describe the bug

I currently have multiple datasets (train+validation) saved as 50MB shards. For one dataset the validation pair is small enough to fit into a single shard and this apparently causes problems when loading the dataset. I created the datasets using a DatasetDict, saved them as 50MB arrow files for streaming and then load each dataset. I have no problem loading any of the other datasets with more than 1 arrow file/shard. 

The error indicates the training set got loaded in arrow format (correct) and the validation set in json (incorrect). This seems to be because some of the metadata files are considered as dataset files. 
```
Error loading /nfs/dataset_pt-uk: Couldn't infer the same data file format for all splits. Got {NamedSplit('train'): ('arrow', {}), NamedSplit('validation'): ('json', {})} 
```

![Image](https://github.com/user-attachments/assets/f6e7596a-dd53-46a9-9a23-4e9cac2ac049)

Concretely, there is a mismatch between the metadata created by the `DatasetDict.save_to_file` and the builder for `datasets.load_dataset`:

https://github.com/huggingface/datasets/blob/e71b0b19d79c7531f9b9bea7c09916b5f6157f42/src/datasets/data_files.py#L107

The `folder_based_builder` lists all files and with 1 arrow file the json files (that are actually metadata) are in the majority.
https://github.com/huggingface/datasets/blob/e71b0b19d79c7531f9b9bea7c09916b5f6157f42/src/datasets/packaged_modules/folder_based_builder/folder_based_builder.py#L58

### Steps to reproduce the bug

Create a dataset with metadata and 1 arrow file in validation and multiple arrow files in the training set, following the above description. In my case, I saved the files via:

```python
        dataset = DatasetDict({
            'train': train_dataset,
            'validation': val_dataset
        })
        
        dataset.save_to_disk(output_path, max_shard_size="50MB")
```

### Expected behavior

The dataset would get loaded.

### Environment info

- `datasets` version: 3.6.0
- Platform: Linux-6.14.0-22-generic-x86_64-with-glibc2.41
- Python version: 3.12.7
- `huggingface_hub` version: 0.31.1
- PyArrow version: 18.1.0
- Pandas version: 2.2.3
- `fsspec` version: 2024.6.1
Issue: loading mozilla-foundation--common_voice_11_0 fails
State: open

### Describe the bug

Hello everyone,

i am trying to load `mozilla-foundation--common_voice_11_0` and it fails. Reproducer 

```
import datasets
datasets.load_dataset("mozilla-foundation/common_voice_11_0", "en", split="test", streaming=True, trust_remote_code=True)
```
and it fails with
```
File ~/opt/envs/.../lib/python3.10/site-packages/datasets/utils/file_utils.py:827, in _add_retries_to_file_obj_read_method.<locals>.read_with_retries(*args, **kwargs)
    825 for retry in range(1, max_retries + 1):
    826     try:
--> 827         out = read(*args, **kwargs)
    828         break
    829     except (
    830         _AiohttpClientError,
    831         asyncio.TimeoutError,
    832         requests.exceptions.ConnectionError,
    833         requests.exceptions.Timeout,
    834     ) as err:

File /usr/lib/python3.10/codecs.py:322, in BufferedIncrementalDecoder.decode(self, input, final)
    319 def decode(self, input, final=False):
    320     # decode input (taking the buffer into account)
    321     data = self.buffer + input
--> 322     (result, consumed) = self._buffer_decode(data, self.errors, final)
    323     # keep undecoded input until the next call
    324     self.buffer = data[consumed:]

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x8b in position 1: invalid start byte
```
When i remove streaming then everything is good but i need `streaming=True`

### Steps to reproduce the bug

```
import datasets
datasets.load_dataset("mozilla-foundation/common_voice_11_0", "en", split="test", streaming=True, trust_remote_code=True)
```

### Expected behavior

Expected that it will download dataset

### Environment info

datasets==3.6.0 
python3.10
on all platforms linux/win/mac

@claude Could you please address this issue

kinda related: https://github.com/huggingface/datasets/issues/7675
Issue: Introduce subset_name as an alias of config_name
State: open
Labels: name: enhancement

### Feature request

Add support for `subset_name` as an alias for `config_name` in the datasets library and related tools (such as loading scripts, documentation, and metadata).

### Motivation

The Hugging Face Hub dataset viewer displays a column named **"Subset"**, which refers to what is currently technically called config_name in the datasets library. This inconsistency has caused confusion for many users, especially those unfamiliar with the internal terminology.

I have repeatedly received questions from users trying to understand what "config" means, and why it doesn’t match what they see as "subset" on the Hub. Renaming everything to `subset_name` might be too disruptive, but introducing subset_name as a clear alias for config_name could significantly improve user experience without breaking backward compatibility.

This change would:
- Align terminology across the Hub UI and datasets codebase
- Reduce user confusion, especially for newcomers
- Make documentation and examples more intuitive


I second this! When you come from the Hub, the intuitive question is "how do I set the subset name", and it's not easily answered from the docs: `subset_name` would answer this directly.

I've submitted PR [#7657](https://github.com/huggingface/datasets/pull/7657) to introduce subset_name as a user-facing alias for name in load_dataset, keeping terminology consistent with the Hub UI (“Subset”). It’s fully backward-compatible and includes a conflict check.

Let me know if you'd like me to include tests as part of the PR — happy to add them if needed!

The main usage is as a positional argument anyway, so I wouldn't necessarily agree that we need an alias (with the risk of confusing users). But happy to have more mentions in the docs of syntaxes like `load_dataset("dataset_name", "subset_name")`

> The main usage is as a positional argument anyway, so I wouldn't necessarily agree that we need an alias (with the risk of confusing users). But happy to have more mentions in the docs of syntaxes like `load_dataset("dataset_name", "subset_name")`

Thanks @lhoestq, totally fair point — especially with positional usage being the norm. I’m happy to align with the team’s direction here. If you'd prefer, I can update this PR to shift the focus to documentation/examples (e.g., showing "subset_name" as the second arg).
Issue: "open" in globals()["__builtins__"], an error occurs: "TypeError: argument of type 'module' is not iterable"
State: open

When I run the following code, an error occurs: "TypeError: argument of type 'module' is not iterable"
```python
print("open" in globals()["__builtins__"])
```
Traceback (most recent call last):
  File "./main.py", line 2, in <module>
    print("open" in globals()["__builtins__"])
          ^^^^^^^^^^^^^^^^^^^^^^
TypeError: argument of type 'module' is not iterable

But this code runs fine in datasets, I don't understand why
[src/datasets/utils/patching.py#L96](https://github.com/huggingface/datasets/blob/3.6.0/src/datasets/utils/patching.py#L96)

@kuanyan9527 Your query is indeed valid. Following could be its reasoning:

Quoting from https://stackoverflow.com/a/11181607:
"By default, when in the `__main__` module,` __builtins__` is the built-in module `__builtin__` (note: no 's'); when in any other module, `__builtins__` is an alias for the dictionary of the `__builtin__` module itself."

Can you confirm if you are running the snippet `print("open" in globals()["__builtins__"])` in the default? In that case, as expected, `__builtins__` is a module which is causing the error. But in the codebase, the class `patch_submodule`, is primarily used in the second circumstance, where it acts as a dictionary. Hence causing the code to function successfully.

Hope this helps.

@kuanyan9527 Are there any more queries in this regards, else please feel free to close the issue.
Thank you.

Your answer is very important to me,thanks.

I encountered this error when running datasets with pypy,
`TypeError: argument of type 'module' is not iterable` in [src/datasets/utils/patching.py#L96](https://github.com/huggingface/datasets/blob/3.6.0/src/datasets/utils/patching.py#L96)
by modifying `globals()["__builtins__"]` to `builtins.__dict__`, importing via `import builtins`.
Can this be applied to the community?
Issue: Proposal: Small Tamil Discourse Coherence Dataset.
State: open

I’m a beginner from NIT Srinagar proposing a dataset of 50 Tamil text pairs for discourse coherence (coherent/incoherent labels) to support NLP research in low-resource languages.
- Size: 50 samples
- Format: CSV with columns (text1, text2, label)
- Use case: Training NLP models for coherence
I’ll use GitHub’s web editor and Google Colab. Please confirm if this fits.
Issue: Graceful Error Handling for cast_column("image", Image(decode=True)) in Hugging Face Datasets
State: open
Labels: name: enhancement

### Feature request

Currently, when using dataset.cast_column("image", Image(decode=True)), the pipeline throws an error and halts if any image in the dataset is invalid or corrupted (e.g., truncated files, incorrect formats, unreachable URLs). This behavior disrupts large-scale processing where a few faulty samples are common.
reference : https://discuss.huggingface.co/t/handle-errors-when-loading-images-404-corrupted-etc/50318/5
                  https://discuss.huggingface.co/t/handling-non-existing-url-in-image-dataset-while-cast-column/69185
                  
Proposed Feature

Introduce a mechanism (e.g., a continue_on_error=True flag or global error handling mode) in Image(decode=True) that:

Skips invalid images and sets them as None, or

Logs the error but allows the rest of the dataset to be processed without interruption.


Example Usage

from datasets import load_dataset, Image

dataset = load_dataset("my_dataset")
dataset = dataset.cast_column("image", Image(decode=True, continue_on_error=True))

Benefits

Ensures robust large-scale image dataset processing.

Improves developer productivity by avoiding custom retry/error-handling code.

Aligns with best practices in dataset preprocessing pipelines that tolerate minor data corruption.


Potential Implementation Options

Internally wrap the decoding in a try/except block.

Return None or a placeholder on failure.

Optionally allow custom error callbacks or logging.

### Motivation

Robustness: Large-scale image datasets often contain a small fraction of corrupt files or unreachable URLs. Halting on the first error forces users to write custom workarounds or preprocess externally.

Simplicity: A built-in flag removes boilerplate try/except logic around every decode step.

Performance: Skipping invalid samples inline is more efficient than a two-pass approach (filter then decode).

### Your contribution


1. API Change
Extend datasets.features.Image(decode=True) to accept continue_on_error: bool = False.

2. Behavior
If continue_on_error=False (default), maintain current behavior: any decode error raises an exception.
If continue_on_error=True, wrap decode logic in try/except:
On success: store the decoded image.
On failure: log a warning (e.g., via logging.warning) and set the field to None (or a sentinel value).


3. Optional Enhancements
Allow a callback hook:
Image(decode=True, continue_on_error=True, on_error=lambda idx, url, exc: ...)
Emit metrics or counts of skipped images.

Hi! This is now handled in PR #7638

Thank you for implementing the suggestion it would be great help in our use case.
Issue: [bug] resume from ckpt skips samples if .map is applied
State: open

### Describe the bug

resume from ckpt skips samples if .map is applied

Maybe related: https://github.com/huggingface/datasets/issues/7538

### Steps to reproduce the bug

```python
from datasets import Dataset
from datasets.distributed import split_dataset_by_node


# Create dataset with map transformation
def create_dataset():
    ds = Dataset.from_dict({"id": list(range(100))})
    ds = ds.to_iterable_dataset(num_shards=4)
    ds = ds.map(lambda x: x) #comment it out to get desired behavior
    ds = split_dataset_by_node(ds, rank=0, world_size=2)
    return ds


ds = create_dataset()

# Iterate and save checkpoint after 10 samples
it = iter(ds)
for idx, sample in enumerate(it):
    if idx == 9:  # Checkpoint after 10 samples
        checkpoint = ds.state_dict()
        print(f"Checkpoint saved at sample: {sample['id']}")
        break

# Continue with original iterator
original_next_samples = []
for idx, sample in enumerate(it):
    original_next_samples.append(sample["id"])
    if idx >= 4:
        break

# Resume from checkpoint
ds_new = create_dataset()
ds_new.load_state_dict(checkpoint)

# Get samples from resumed iterator
it_new = iter(ds_new)
resumed_next_samples = []
for idx, sample in enumerate(it_new):
    resumed_next_samples.append(sample["id"])
    if idx >= 4:
        break

print(f"\nExpected next samples: {original_next_samples}")
print(f"Actual next samples:   {resumed_next_samples}")
print(
    f"\n❌ BUG: {resumed_next_samples[0] - original_next_samples[0]} samples were skipped!"
)

```

With map
```
Checkpoint saved at sample: 9

Expected next samples: [10, 11, 12, 13, 14]
Actual next samples:   [50, 51, 52, 53, 54]

❌ BUG: 40 samples were skipped!
```

### Expected behavior

without map
```
Expected next samples: [10, 11, 12, 13, 14]
Actual next samples:   [10, 11, 12, 13, 14]

❌ BUG: 0 samples were skipped!
```

### Environment info

datasets == 3.6.0

Thanks for reporting this — it looks like a separate but related bug to #7538, which involved sample loss when resuming an `IterableDataset` wrapped in `FormattedExamplesIterable`. That was resolved in #7553 by re-batching the iterable to track offset correctly.

In this case, the issue seems to arise specifically from applying `.map()` before sharding and checkpointing. That wraps the iterable in `MappedExamplesIterable`, which may not preserve or propagate `shard_example_idx` correctly across `.state_dict()` and `.load_state_dict()` calls.

You can see that without `.map()`, resume works fine — but with `.map()`, it jumps from sample 9 to 50, skipping the rest of the shard.

I'll dig deeper into how `MappedExamplesIterable` manages offsets and whether it supports proper checkpoint resumption. If not, we might need a fix similar to the one in #7553, or a wrapper to preserve resume metadata.

Happy to help fix it!


Let me know if a dedicated test case is required — happy to add one!
Issue: Creating a HF Dataset from lakeFS with S3 storage takes too much time!
State: closed

Hi,

I’m new to HF dataset and I tried to create datasets based on data versioned in **lakeFS** _(**MinIO** S3 bucket as storage backend)_

Here I’m using ±30000 PIL image from MNIST data however it is taking around 12min to execute, which is a lot!

From what I understand, it is loading the images into cache then building the dataset.
– Please find bellow the execution screenshot –

Is there a way to optimize this or am I doing something wrong?

Thanks!

![Image](https://github.com/user-attachments/assets/c79257c8-f023-42a9-9e6f-0898b3ea93fe)

### > Update

The bottleneck, from what I understand, was making one network request per file

For 30k images, this meant 30k separate GET requests to the MinIO server through the S3 API, and that was killing the performance

Using webDataset to transform the large number of files to few .tar files and passing “webdataset” instead of “imagefolder” to the load_dataset function worked perfectly (took only ~11s)
Issue: #Dataset Make "image" column appear first in dataset preview UI
State: closed

Hi!

#Dataset

I’m currently uploading a dataset that includes an `"image"` column (PNG files), along with some metadata columns. The dataset is loaded from a .jsonl file. My goal is to have the "image" column appear as the first column in the dataset card preview UI on the :hugs: Hub.

However, at the moment, the `"image"` column is not the first—in fact, it appears last, which is not ideal for the presentation I’d like to achieve.

I have a couple of questions:

Is there a way to force the dataset card to display the `"image"` column first?
Is there currently any way to control or influence the column order in the dataset preview UI?
Does the order of keys in the .jsonl file or the features argument affect the display order?
Thanks again for your time and help! :blush:

Hi ! It should follow the same order as the order of the keys in the metadata file

Hi! Thank you for your answer. 

As you said it, I I forced every key in every JSON to have an order using `collections. OrderedDict` in Python. Now, it works!

TY
Issue: Unwanted column padding in nested lists of dicts
State: closed

```python
from datasets import Dataset

dataset = Dataset.from_dict({
    "messages": [
        [
            {"a": "...",},
            {"b": "...",},
        ],
    ]
})
print(dataset[0])
```

What I get:
```
{'messages': [{'a': '...', 'b': None}, {'a': None, 'b': '...'}]}
```

What I want:

```
{'messages': [{'a': '...'}, {'b': '...'}]}
```

Is there an easy way to automatically remove these auto-filled null/none values?

If not, I probably need a recursive none exclusion function, don't I?

Datasets 3.6.0

Answer from @lhoestq:

> No
> This is because Arrow and Parquet a columnar format: they require a fixed type for each column. So if you have nested dicts, each item should have the same subfields

The way around I found is the handle it after sampling with this function:

```python
def remove_padding(example):
    if isinstance(example, list):
        return [remove_padding(value) if isinstance(value, (dict, list)) else value for value in example]
    elif isinstance(example, Mapping):
        return {
            key: remove_padding(value) if isinstance(value, (dict, list)) else value
            for key, value in example.items()
            if value is not None
        }
    else:
        raise TypeError("Input must be a list or a dictionary.")

# Example:
example = next(iter(dataset))
example = remove_padding(example)
```
Issue: Code example for dataset.add_column() does not reflect correct way to use function
State: closed

https://github.com/huggingface/datasets/blame/38d4d0e11e22fdbc4acf373d2421d25abeb43439/src/datasets/arrow_dataset.py#L5925C10-L5925C10

The example seems to suggest that dataset.add_column() can add column inplace, however, this is wrong -- it cannot. It returns a new dataset with the column added to it.

Hi @shaily99 

Thanks for pointing this out — you're absolutely right!

The current example in the docstring for add_column() implies in-place modification, which is misleading since add_column() actually returns a new dataset.

#self-assign
Issue: i cant confirm email
State: open

### Describe the bug

This is dificult, I cant confirm email because I'm not get any email!
I cant post forum because I cant confirm email!
I can send help desk because... no exist on web page.

paragraph 44

### Steps to reproduce the bug

rthjrtrt

### Expected behavior

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### Environment info

sdgfswdegfwe

Will you please clarify the issue by some screenshots or more in-depth explanation?

![Image](https://github.com/user-attachments/assets/ebe58239-72ef-43f6-a849-35736878fbf3)
This is clarify answer. I have not received a letter.

**The graphic at the top shows how I don't get any letter. Can you show in a clear way how you don't get a letter from me?**
Issue: `push_to_hub` is not concurrency safe (dataset schema corruption)
State: closed

### Describe the bug

Concurrent processes modifying and pushing a dataset can overwrite each others' dataset card, leaving the dataset unusable.

Consider this scenario:
- we have an Arrow dataset
- there are `N` configs of the dataset
- there are `N` independent processes operating on each of the individual configs (e.g. adding a column, `new_col`)
- each process calls `push_to_hub` on their particular config when they're done processing
- all calls to `push_to_hub` succeed
- the `README.md` now has some configs with `new_col` added and some with `new_col` missing

Any attempt to load a config (using `load_dataset`) where `new_col` is missing will fail because of a schema mismatch between `README.md` and the Arrow files. Fixing the dataset requires updating `README.md` by hand with the correct schema for the affected config. In effect, `push_to_hub` is doing a `git push --force` (I found this behavior quite surprising).

We have hit this issue every time we run processing jobs over our datasets and have to fix corrupted schemas by hand.

Reading through the code, it seems that specifying a [`parent_commit`](https://github.com/huggingface/huggingface_hub/blob/v0.32.4/src/huggingface_hub/hf_api.py#L4587) hash around here https://github.com/huggingface/datasets/blob/main/src/datasets/arrow_dataset.py#L5794 would get us to a normal, non-forced git push, and avoid schema corruption. I'm not familiar enough with the code to know how to determine the commit hash from which the in-memory dataset card was loaded.

### Steps to reproduce the bug

See above.

### Expected behavior

Concurrent edits to disjoint configs of a dataset should never corrupt the dataset schema.

### Environment info

- `datasets` version: 2.20.0
- Platform: Linux-5.15.0-118-generic-x86_64-with-glibc2.35
- Python version: 3.10.14
- `huggingface_hub` version: 0.30.2
- PyArrow version: 19.0.1
- Pandas version: 2.2.2
- `fsspec` version: 2023.9.0

@lhoestq can you please take a look? I've submitted a PR that fixes this issue. Thanks.

Thanks for the ping ! As I said in https://github.com/huggingface/datasets/pull/7605 there is maybe a more general approach using retries :)

Dropping this due to inactivity; we've implemented push_to_hub outside of HF datasets that's concurrency safe. Feel free to use the code I provided as a starting point if there's still interest in addressing this issue.

Exploring another fix here: https://github.com/huggingface/datasets/issues/7600
Issue: My already working dataset (when uploaded few months ago) now is ignoring metadata.jsonl
State: closed

### Describe the bug

Hi everyone, I uploaded my dataset https://huggingface.co/datasets/PRAIG/SMB a few months ago while I was waiting for a conference acceptance response. Without modifying anything in the dataset repository now the Dataset viewer is not rendering the metadata.jsonl annotations, neither it is being downloaded when using load_dataset. Can you please help? Thank you in advance.

### Steps to reproduce the bug

from datasets import load_dataset
ds = load_dataset("PRAIG/SMB")
ds = ds["train"]

### Expected behavior

 It is expected to have all the metadata available in the jsonl file. Fields like: "score_id", "original_width", "original_height", "regions"... among others.

### Environment info

datasets==3.6.0, python 3.13.3 (but he problem is already in the huggingface dataset page)

Maybe its been a recent update, but i can manage to load the metadata.jsonl separately from the images with:

```
metadata = load_dataset("PRAIG/SMB", split="train", data_files=["*.jsonl"])
images = load_dataset("PRAIG/SMB", split="train")
```
Do you know it this is an expected behaviour? This makes my dataset viewer to only load the images without the labeling of metadata.jsonl.

Thanks

Hi ! this is because we now expect the metadata file to be inside the directory named after the split "train" (this way each split can have its own metadata and can be loaded independently)

You can fix that by configuring it explicitly in the dataset's README.md header:

```yaml
configs:
- config_name: default
  data_files:
  - split: train
    path:
    - "train/**/*.png"
    - "metadata.jsonl"
```

(or by moving the metadata.jsonl in train/ but in this case you also have to modify the content of the JSONL to fix the relative paths to the images)

Thank you very much, dataset viewer is already working as expected!!
Issue: Download datasets from a private hub in 2025
State: closed
Labels: name: enhancement

### Feature request

In the context of a private hub deployment, customers would like to use load_dataset() to load datasets from their hub, not from the public hub. This doesn't seem to be configurable at the moment and it would be nice to add this feature.

The obvious workaround is to clone the repo first and then load it from local storage, but this adds an extra step. It'd be great to have the same experience regardless of where the hub is hosted.

This issue was raised before here: https://github.com/huggingface/datasets/issues/3679
@juliensimon

### Motivation

none

### Your contribution

none

Hi ! First, and in the general case, Hugging Face does offer to host private datasets, and with a subscription you can even choose the region in which the repositories are hosted (US, EU)

Then if you happen to have a private deployment, you can set the HF_ENDPOINT environment variable (same as in https://github.com/huggingface/transformers/issues/38634)

Thank you @lhoestq. Works as described!