noamaanMulla-03/datasets-issues huggingface dataset:
Attempting to return a rank 3 grayscale image from dataset.map results in extreme slowdown 

### Describe the bug

Background: Digital images are often represented as a  (Height, Width, Channel) tensor. This is the same for huggingface datasets that contain images. These images are loaded in Pillow containers which offer, for example, the `.convert` method.

I can convert an image from a (H,W,3) shape to a grayscale (H,W) image and I have no problems with this. But when attempting to return a (H,W,1) shaped matrix from a map function, it never completes and sometimes even results in an OOM from the OS.


I've used various methods to expand a (H,W) shaped array to a (H,W,1) array. But they all resulted in extremely long map operations consuming a lot of CPU and RAM.

### Steps to reproduce the bug

Below is a minimal example using two methods to get the desired output. Both of which don't work
```py
import tensorflow as tf
import datasets
import numpy as np

ds = datasets.load_dataset("project-sloth/captcha-images")
to_gray_pillow = lambda sample: {'image': np.expand_dims(sample['image'].convert("L"), axis=-1)}
ds_gray = ds.map(to_gray_pillow)

# Alternatively
ds = datasets.load_dataset("project-sloth/captcha-images").with_format("tensorflow")
to_gray_tf = lambda sample: {'image': tf.expand_dims(tf.image.rgb_to_grayscale(sample['image']), axis=-1)}
ds_gray = ds.map(to_gray_tf)
```

### Expected behavior

I expect the map operation to complete and return a new dataset containing grayscale images in a (H,W,1) shape.

### Environment info

datasets 2.21.0
python tested with both 3.11 and 3.12
host os : linux
Fix data file module inference

I saved a dataset with two splits to disk with `DatasetDict.save_to_disk`. The train is bigger and ended up in 10 shards, whereas the test split only resulted in 1 split.

Now when trying to load the dataset, an error is raised that not all splits have the same data format:

> ValueError: Couldn't infer the same data file format for all splits. Got {NamedSplit('train'): ('arrow', {}), NamedSplit('test'): ('json', {})}

This is not expected because both splits are saved as arrow files.

I did some debugging and found that this is the case because the list of data_files includes a `state.json` file. 

Now this means for train split I get 10 ".arrow" and 1 ".json" file. Since datasets picks based on the most common extension this is correctly inferred as "arrow". In the test split, there is 1 .arrow and 1 .json file. Given the function description:

> It picks the module based on the most common file extension.
    In case of a draw ".parquet" is the favorite, and then alphabetical order.

This is not quite true though, because in a tie the extensions are actually based on reverse-alphabetical order:
```
for (ext, _), _ in sorted(extensions_counter.items(), key=sort_key, *reverse=True*):
```

Which thus leads to the module wrongly inferred as "json", whereas it should be "arrow", matching the train split.

I first thought about adding "state.json" in the list of excluded files for the inference: https://github.com/huggingface/datasets/blob/main/src/datasets/load.py#L513. However, I think from digging into the code it looks like the right thing to do is to exclude it in the list of `data_files` to start with, because it is more of a metadata than a data file.


Hi ! datasets saved using `save_to_disk` should be loaded with `load_from_disk` ;)

It is convienient to just pass in a path to a local dataset or one from the hub and use the same function to load it. Is it not possible to get this fix merged in to allow this? 

We can modify `save_to_disk` to write the dataset in a structure supported by the Hub in this case, it's kind of a legacy function anyway
datasets cannot handle nested json if features is given.

### Describe the bug

I have a json named temp.json.
```json
{"ref1": "ABC", "ref2": "DEF", "cuts":[{"cut1": 3, "cut2": 5}]}
```
I want to load it.
```python
ds = datasets.load_dataset('json', data_files="./temp.json", features=datasets.Features({
    'ref1': datasets.Value('string'),
    'ref2': datasets.Value('string'),
    'cuts': datasets.Sequence({
        "cut1": datasets.Value("uint16"),
        "cut2": datasets.Value("uint16")
    })
}))
```
The above code does not work. However, I can load it without giving features.
```python
ds = datasets.load_dataset('json', data_files="./temp.json")
```
Is it possible to load integers as uint16 to save some memory?

### Steps to reproduce the bug

As in the bug description.

### Expected behavior

The data are loaded and integers are uint16.

### Environment info

Copy-and-paste the text below in your GitHub issue.

- `datasets` version: 2.21.0
- Platform: Linux-5.15.0-118-generic-x86_64-with-glibc2.35
- Python version: 3.11.9
- `huggingface_hub` version: 0.24.5
- PyArrow version: 17.0.0
- Pandas version: 2.2.2
- `fsspec` version: 2024.5.0


Hi ! `Sequence` has a weird behavior for dictionaries (from tensorflow-datasets), use a regular list instead:

```python
ds = datasets.load_dataset('json', data_files="./temp.json", features=datasets.Features({
    'ref1': datasets.Value('string'),
    'ref2': datasets.Value('string'),
    'cuts': [{
        "cut1": datasets.Value("uint16"),
        "cut2": datasets.Value("uint16")
    }]
}))
```

> Hi ! `Sequence` has a weird behavior for dictionaries (from tensorflow-datasets), use a regular list instead:
> 
> ```python
> ds = datasets.load_dataset('json', data_files="./temp.json", features=datasets.Features({
>     'ref1': datasets.Value('string'),
>     'ref2': datasets.Value('string'),
>     'cuts': [{
>         "cut1": datasets.Value("uint16"),
>         "cut2": datasets.Value("uint16")
>     }]
> }))
> ```
Thank you!


It works.
Loading dataset from large GCS bucket very slow since 2.14

### Describe the bug

Since updating to >2.14 we have very slow access to our parquet files on GCS when loading a dataset (>30 min vs 3s). Our GCS bucket has many objects and resolving globs is very slow. I could track down the problem to this change:
https://github.com/huggingface/datasets/blame/bade7af74437347a760830466eb74f7a8ce0d799/src/datasets/data_files.py#L348 
The underlying implementation with gcsfs is really slow. Could you go back to the old way if we are simply giving the parquet files and no glob pattern?

Thank you.




### Steps to reproduce the bug

Load a dataset from a GCS bucket that has many files.

### Expected behavior

Used to be fast (3s) in 2.13

### Environment info

datasets==2.14.5


I've also encountered this issue recently and want to ask if this has been seen.

@albertvillanova for visibility - I'm not sure who the right person is to tag, but I noticed you were active recently so perhaps you can direct this to the right person.

Thanks!
Add MedImg for streaming

### Feature request

Host the MedImg dataset (similar to Imagenet but for biomedical images). 

### Motivation

There is a clear need for biomedical image foundation models and large scale biomedical datasets that are easily streamable. This would be an excellent tool for the biomedical community.

### Your contribution

MedImg can be found [here](https://www.cuilab.cn/medimg/#).

Labels: name: dataset request

@mariosasko, @lhoestq, @albertvillanova
Hello! Can anyone help? or can you guys suggest who can help with this?

Hi ! Feel free to download the dataset and create a `Dataset` object with it.

Then your'll be able to use `push_to_hub()` to upload the dataset to HF in Parquet format and make it streamable :)

> Hi ! Feel free to download the dataset and create a `Dataset` object with it.
> 
> Then your'll be able to use `push_to_hub()` to upload the dataset to HF in Parquet format and make it streamable :)

The dataset is several TB in total, which I do not have the resources to handle.

Hi @lhoestq and @albertvillanova , just following up about this.

for big datasets you can push_to_hub one part at a time (e.g. as different splits) and merge the parts (just a simple modification in the YAML part of the README)

Sure, that makes sense. However, isn't there a size limit to what typical users can push?

Yes there is a limit, simply let us know by email at datasets [at] huggingface.co - this way we can give you a storage grant also help making sure the dataset is all good for people to use it easily

> Yes there is a limit, simply let us know by email at datasets [at] huggingface.co - this way we can give you a storage grant also help making sure the dataset is all good for people to use it easily

Got it, that would be great.
WebDataset loader splits keys differently than WebDataset library

As reported by @ragavsachdeva (see discussion here: https://github.com/huggingface/datasets/pull/7144#issuecomment-2348307792), our webdataset loader is not aligned with the `webdataset` library when splitting keys from filenames.

For example, we get a different key splitting for filename `/some/path/22.0/1.1.png`:
- datasets library: `/some/path/22` and `0/1.1.png`
- webdataset library: `/some/path/22.0/1`, `1.png`

```python
import webdataset as wds

wds.tariterators.base_plus_ext("/some/path/22.0/1.1.png")
# ('/some/path/22.0/1', '1.png')
```


Labels: name: bug
Specifying datatype when adding a column to a dataset.

### Feature request

There should be a way to specify the datatype of a column in `datasets.add_column()`. 

### Motivation

To specify a custom datatype, we have to use `datasets.add_column()` followed by `datasets.cast_column()` which is slow for large datasets. Another workaround is to pass a `numpy.array()` of desired type to the `datasets.add_column()` function.

IMO this functionality should be natively supported.

https://discuss.huggingface.co/t/add-column-with-a-particular-type-in-datasets/95674



### Your contribution

I can submit a PR for this.

Labels: name: enhancement

#self-assign
Modify add_column() to optionally accept a FeatureType as param

Fix #7142.

**Before (Add + Cast)**:

```
from datasets import load_dataset, Value
ds = load_dataset("rotten_tomatoes", split="test")
lst = [i for i in range(len(ds))]

ds = ds.add_column("new_col", lst)
# Assigns int64 to new_col by default
print(ds.features)

ds = ds.cast_column("new_col", Value(dtype="uint16", id=None))
print(ds.features)
```


**Before (Numpy Workaround)**:

```
from datasets import load_dataset
import numpy as np
ds = load_dataset("rotten_tomatoes", split="test")
lst = [i for i in range(len(ds))]

ds = ds.add_column("new_col", np.array(lst, dtype=np.uint16))
print(ds.features)
```

**After**:
```
from datasets import load_dataset, Value
ds = load_dataset("rotten_tomatoes", split="test")
lst = [i for i in range(len(ds))]
val = Value(dtype="uint16", id=None))
ds = ds.add_column("new_col", lst, feature=val)
print(ds.features)
```


Requesting review @lhoestq 
I will also update the docs if this looks good.

Cool ! maybe you can rename the argument `feature` and with type `FeatureType` ? This way it would work the same way as `.cast_column()` ?

@lhoestq Since there is no way to get a `pyarrow.Schema` from a `FeatureType`, I had to go via `Features`. How does this look?

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7143). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

@lhoestq done!

@lhoestq anything pending on this?
Dataset viewer not working! Failure due to more than 32 splits.

Hello guys, 

I have a dataset and I didn't know I couldn't upload more than 32 splits. Now, my dataset viewer is not working. I don't have the dataset locally on my node anymore and recreating would take a week. And I have to publish the dataset coming Monday. I read about the practice, how I can resolve it and avoid this issue in the future. But, at the moment I need a hard fix for two of my datasets. 

And I don't want to mess or change anything and allow everyone in public to see the dataset and interact with it. Can you please help me?

https://huggingface.co/datasets/laion/Wikipedia-X
https://huggingface.co/datasets/laion/Wikipedia-X-Full


I have fixed it! But I would appreciate a new feature wheere I could iterate over and see what each file looks like.
Support ndjson data files

Support `ndjson` (Newline Delimited JSON) data files.

Fix #7153.


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7154). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

Thanks for your review, @severo.

Yes, I was aware of this. From internal conversation:
> Please note that although NDJSON was planned to be submitted as an RFC standard spec, it is no longer maintained:
> - See note from the author: https://github.com/ndjson/ndjson-spec/issues/35#issuecomment-1285673417
> - See that their official website domain has expired: https://ndjson.org/ 

The purpose of this PR is just supporting datasets with ndjson data files (e.g. Wikimedia Enterprise data files), but it should not imply any recommendation or endorsement of this format from our part.
Cache only changed columns?

### Feature request

Cache only the actual changes to the dataset i.e. changed columns.

### Motivation

I realized that caching actually saves the complete dataset again.
This is especially problematic for image datasets if one wants to only change another column e.g. some metadata and then has to save 5 TB again.

### Your contribution

Is this even viable in the current architecture of the package?
I quickly looked into it and it seems it would require significant changes.

I would spend some time looking into this but maybe somebody could help with the feasibility and some plan to implement before spending too much time on it?

Labels: name: enhancement

so I guess a workaround to this is to simply remove all columns except the ones to cache and then add them back with `concatenate_datasets(..., axis=1)`.

yes this is the right workaround. We're keeping the cache like this to make it easier for people to delete intermediate cache files
cudf-cu12 24.4.1, ibis-framework 8.0.0 requires pyarrow<15.0.0a0,>=14.0.1,pyarrow<16,>=2 and datasets 2.21.0 requires pyarrow>=15.0.0

### Describe the bug

!pip install accelerate>=0.16.0 torchvision transformers>=4.25.1 datasets>=2.19.1 ftfy tensorboard Jinja2 peft==0.7.0

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.
cudf-cu12 24.4.1 requires pyarrow<15.0.0a0,>=14.0.1, but you have pyarrow 17.0.0 which is incompatible.
ibis-framework 8.0.0 requires pyarrow<16,>=2, but you have pyarrow 17.0.0 which is incompatible.

to solve above error
!pip install pyarrow==14.0.1

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 2.21.0 requires pyarrow>=15.0.0, but you have pyarrow 14.0.1 which is incompatible.

### Steps to reproduce the bug

!pip install datasets>=2.19.1

### Expected behavior

run without dependency error

### Environment info

Diffusers version: 0.31.0.dev0

Platform: Linux-6.1.85+-x86_64-with-glibc2.35
Running on Google Colab?: Yes
Python version: 3.10.12
PyTorch version (GPU?): 2.3.1+cu121 (True)
Flax version (CPU?/GPU?/TPU?): 0.8.4 (gpu)
Jax version: 0.4.26
JaxLib version: 0.4.26
Huggingface_hub version: 0.23.5
Transformers version: 4.42.4
Accelerate version: 0.32.1
PEFT version: 0.7.0
Bitsandbytes version: not installed
Safetensors version: 0.4.4
xFormers version: not installed
Accelerator: Tesla T4, 15360 MiB
Using GPU in script?:
Using distributed or parallel set-up in script?:


@sayakpaul  please advice 

Hits the same dependency conflict
Support JSON lines with missing struct fields

Support JSON lines with missing struct fields.

Fix #7159.

The implemented test raised:
```
TypeError: Couldn't cast array of type
struct<age: int64>
to
{'age': Value(dtype='int32', id=None), 'name': Value(dtype='string', id=None)}
```


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7160). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Set explicit seed in iterable dataset ddp shuffling example 

### Describe the bug

In the examples section of the iterable dataset docs https://huggingface.co/docs/datasets/en/package_reference/main_classes#datasets.IterableDataset
the ddp example shuffles without seeding

```python
from datasets.distributed import split_dataset_by_node
ids = ds.to_iterable_dataset(num_shards=512)
ids = ids.shuffle(buffer_size=10_000)  # will shuffle the shards order and use a shuffle buffer when you start iterating
ids = split_dataset_by_node(ds, world_size=8, rank=0)  # will keep only 512 / 8 = 64 shards from the shuffled lists of shards when you start iterating
dataloader = torch.utils.data.DataLoader(ids, num_workers=4)  # will assign 64 / 4 = 16 shards from this node's list of shards to each worker when you start iterating
for example in ids:
    pass
```

This code would - I think - raise an error due to the lack of an explicit seed:

https://github.com/huggingface/datasets/blob/2eb4edb97e1a6af2ea62738ec58afbd3812fc66e/src/datasets/iterable_dataset.py#L1707-L1711


### Steps to reproduce the bug

Run example code

### Expected behavior

Add explicit seeding to example code

### Environment info

latest datasets


thanks for reporting !
fix increase_load_count

it was failing since 3.0 and therefore not updating download counts on HF or in our dashboard


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7165). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

I tested a few load_dataset and they do show up in download stats now

Thanks for having noticed and fixed.
Offline dataset viewer

### Feature request

The dataset viewer feature is very nice. It enables to the user to easily view the dataset. However, when working for private companies we cannot always upload the dataset to the hub. Is there a way to create dataset viewer offline? I.e. to run a code that will open some kind of html or something that makes it easy to view the dataset.

### Motivation

I want to easily view my dataset even when it is hosted locally.

### Your contribution

N.A.

Labels: name: enhancement

name: dataset-viewer

Hi, thanks for the suggestion. It's not possible at the moment. The viewer is part of the Hub codebase and only works on public datasets. Also, it relies on [Datasets Server](https://github.com/huggingface/datasets-server/), which prepares the data and provides an API to access the rows, size, etc.

If you're interested in hosting your data as a private dataset on the Hub, you might want to look at https://github.com/huggingface/datasets-server/issues/39.

Hi, we are building an offline dataset viewer: https://github.com/Renumics/spotlight
It supports many HF datasets, but currently you have to use it via Pandas:
df=ds.to_pandas()
spotlight.show(df)

Would love to hear from you if that works for your use case. If not, feel free to open an issue on the repo: https://github.com/Renumics/spotlight/issues

@ssuwelack thank you! I will definitely try it out.

Related issues:
- https://github.com/huggingface/datasets-server/issues/213
- https://github.com/huggingface/datasets-server/issues/441
- https://github.com/huggingface/datasets/issues/6014

Closing for now, as developing and maintaining an offline viewer is not planned.

@yuvalkirstain the dataset viewer is now available on private datasets for [PRO users](https://huggingface.co/pricing#pro) and [Enterprise Hub orgs](https://huggingface.co/enterprise). Would it fit your needs?

Hi @ssuwelack I tried loading a HF dataset with your viewer but got this error https://github.com/Renumics/spotlight/issues/461 hope the team can help me on this. Thanks!
JSON lines with empty struct raise ArrowTypeError

JSON lines with empty struct raise ArrowTypeError: struct fields don't match or are in the wrong order

See example: https://huggingface.co/datasets/wikimedia/structured-wikipedia/discussions/5

> ArrowTypeError: struct fields don't match or are in the wrong order: Input fields: struct<> output fields: struct<pov_count: int64, update_count: int64, citation_needed_count: int64>

Related to:
- #7159

Labels: name: bug
Support JSON lines with missing columns

Support JSON lines with missing columns.

Fix #7169.

The implemented test raised:
```
datasets.table.CastError: Couldn't cast
age: int64
to
{'age': Value(dtype='int32', id=None), 'name': Value(dtype='string', id=None)}
because column names don't match
```

Related to:
- #7160 
- #7162


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7170). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
CI is broken: No solution found when resolving dependencies

See: https://github.com/huggingface/datasets/actions/runs/11046967444/job/30687294297
```
Run uv pip install --system -r additional-tests-requirements.txt --no-deps
  × No solution found when resolving dependencies:
  ╰─▶ Because the current Python version (3.8.18) does not satisfy Python>=3.9
      and torchdata==0.10.0a0+1a98f21 depends on Python>=3.9, we can conclude
      that torchdata==0.10.0a0+1a98f21 cannot be used.
      And because only torchdata==0.10.0a0+1a98f21 is available and
      you require torchdata, we can conclude that your requirements are
      unsatisfiable.
Error: Process completed with exit code 1.
```

Labels: name: bug
Add torchdata as a regular test dependency

Add `torchdata` as a regular test dependency.

Note that previously, `torchdata` was installed from their repo and current main branch (0.10.0.dev) requires Python>=3.9.

Also note they made a recent release: 0.8.0 on Jul 31, 2024.

Fix #7171.


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7172). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Fix export to JSON when dataset larger than batch size

Fix export to JSON (`lines=False`) when dataset larger than batch size.

Fix #7037.


The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7039). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

The test before confirms the bug.

There are different possible solutions to this issue:
- the easiest would be to write multiple JSON files, one for each batch; this solution can be done in parallel if `num_proc` is passed
- alternatively, we could tweak the writing and remove the extra `[` and `]` characters; this solution will only be valid if `orient="records"`
- others?

@albertvillanova I was planning to approach it in the second way for `orient="records"` , `orient="values"` and `orient="index"`. For `orient="split"`, the columns and index can be written in one go and the data can be written in streaming manner. For `orient="columns"`, each column can be written in a streaming way.  LMK if I should go ahead with this.

> The test before confirms the bug.
> 
> There are different possible solutions to this issue:
> 
>     * the easiest would be to write multiple JSON files, one for each batch; this solution can be done in parallel if `num_proc` is passed
> 
>     * alternatively, we could tweak the writing and remove the extra `[` and `]` characters; this solution will only be valid if `orient="records"`
> 
>     * others?