MarouaneSanhaji/github-issues huggingface dataset:
Argument type for map function changes when using `input_columns` for `IterableDataset`
State: closed

### Describe the bug

I wrote `tokenize(examples)` function as an argument for `map` function for `IterableDataset`.
It process dictionary type `examples` as a parameter.
It is used in `train_dataset = train_dataset.map(tokenize, batched=True)`
No error is raised.

And then, I found some unnecessary keys and values in `examples` so I added `input_columns` argument to `map` function to select keys and values.
It gives me an error saying
```
TypeError: tokenize() takes 1 positional argument but 3 were given.
```

The code below matters.
https://github.com/huggingface/datasets/blob/406b2212263c0d33f267e35b917f410ff6b3bc00/src/datasets/iterable_dataset.py#L687

For example, `inputs = {"a":1, "b":2, "c":3}`.
If `self.input_coluns` is `None`,
`inputs` is a dictionary type variable and `function_args` becomes a `list` of a single `dict` variable.
`function_args` becomes `[{"a":1, "b":2, "c":3}]`

Otherwise, lets say `self.input_columns = ["a", "c"]`
`[inputs[col] for col in self.input_columns]` results in `[1, 3]`.
I think it should be `[{"a":1, "c":3}]`.

I want to ask if the resulting format is intended.
Maybe I can modify `tokenize()` to have 2 parameters in this case instead of having 1 dictionary.
But this is confusing to me.
Or it should be fixed as `[{col:inputs[col] for col in self.input_columns}]`

### Steps to reproduce the bug

Run `map` function of `IterableDataset` with `input_columns` argument.

### Expected behavior

`function_args` looks better to have same format.
I think it should be `[{"a":1, "c":3}]`.

### Environment info

dataset version: 2.12
python: 3.8

Yes, this is intended.
Dataset string representation enhancement
State: open

my attempt at #6010  
not sure if this is the right way to go about it, I will wait for your feedback 

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6016). All of your documentation changes will be reflected on that endpoint.

It we could have something similar to Polars, that would be great.

This is what Polars outputs: 
* `__repr__`/`__str__` :
```
shape: (67_349, 3)
┌───────┬───────────────────────────────────┬───────┐
│ idx   ┆ sentence                          ┆ label │
│ ---   ┆ ---                               ┆ ---   │
│ i32   ┆ str                               ┆ i64   │
╞═══════╪═══════════════════════════════════╪═══════╡
│ 0     ┆ hide new secretions from the par… ┆ 0     │
│ 1     ┆ contains no wit , only labored g… ┆ 0     │
│ 2     ┆ that loves its characters and co… ┆ 1     │
│ 3     ┆ remains utterly satisfied to rem… ┆ 0     │
│ …     ┆ …                                 ┆ …     │
│ 67345 ┆ anguish , anger and frustration   ┆ 0     │
│ 67346 ┆ at achieving the modest , crowd-… ┆ 1     │
│ 67347 ┆ a patient viewer                  ┆ 1     │
│ 67348 ┆ this new jangle of noise , mayhe… ┆ 0     │
└───────┴───────────────────────────────────┴───────┘
```

* `_repr_html_`:
<img width="251" alt="Screenshot 2023-07-12 at 18 25 58" src="https://github.com/huggingface/datasets/assets/47462742/5d04519d-f302-4411-9fbc-7445bdf53b23">
[FR] `map` should reuse unchanged columns from the previous dataset to avoid disk usage
State: open

### Feature request

Currently adding a new column with `map` will cause all the data in the dataset to be duplicated and stored/cached on the disk again. It should reuse unchanged columns. 

### Motivation

This allows having datasets with different columns but sharing some basic columns. Currently, these datasets would become too expensive to store and one would need some kind of on-the-fly join; which also doesn't seem implemented.

### Your contribution

_

You can use the `remove_columns` parameter in `map` to avoid duplicating the columns (and save disk space) and then concatenate the original dataset with the map result:
```python
from datasets import concatenate_datasets
# dummy example
ds_new = ds.map(lambda x: {"new_col": x["col"] + 2}, remove_columns=ds.column_names)
ds_combined = concatenate_datasets([ds, ds_new], axis=1)
```

Doing this automatically is hard to implement efficiently unless we know ahead of time which existing columns will be modified by a `map` transform. We have this info when `input_columns` are specified, so I think this is the only case we can optimize.

Hi @mariosasko 👋 I’d like to start working on this issue.
Improve `Dataset`'s string representation
State: open

Currently, `Dataset.__repr__` outputs a dataset's column names and the number of rows. We could improve it by printing its features and the first few rows.

We should also implement `_repr_html_` to have a rich HTML representation in notebooks/Streamlit.

I want to take a shot at this if possible 

Yes, feel free to work on this.

You can check the PyArrow Table `__repr__`  and Polars DataFrame `__repr__`/`_repr_html_` implementations for some pointers/ideas.

@mariosasko are there any other similar issues that I could work on? I see this has been already solved.
Dataset.from_generator consistently freezes at ~1000 rows
State: closed

### Describe the bug

Whenever I try to create a dataset which contains images using `Dataset.from_generator`, it freezes around 996 rows. I suppose it has something to do with memory consumption, but there's more memory available. I

Somehow it worked a few times but mostly this makes the datasets library much more cumbersome to work with because generators are the easiest way to turn an existing dataset into a Hugging Face dataset.

I've let it run in the frozen state for way longer than it can possibly take to load the actual dataset.

Let me know if you have ideas how to resolve it!

### Steps to reproduce the bug

```python
from datasets import Dataset
import numpy as np

def gen():
    for row in range(10000):
        yield {"i": np.random.rand(512, 512, 3)}
        
Dataset.from_generator(gen)
# -> 90% of the time gets stuck around 1000 rows
```

### Expected behavior

Should continue and go through all the examples yielded by the generator, or at least throw an error or somehow communicate what's going on.

### Environment info

- `datasets` version: 2.8.0
- Platform: Linux-5.15.0-52-generic-x86_64-with-glibc2.29
- Python version: 3.8.10
- PyArrow version: 12.0.1
- Pandas version: 1.5.1


By default, we write data to disk (so it can be memory-mapped) every 1000 rows/samples. You can control this with the `writer_batch_size` parameter. Also, when working with fixed-size arrays, the `ArrayXD` feature types yield better performance (e.g., in your case, `features=datasets.Features({"i": datasets.Array3D(shape=(512,512,3), dtype="float32")})` should be faster).

Our support for multi-dim arrays could be better, and we plan to improve it as part of https://github.com/huggingface/datasets/issues/5272.

> By default, we write data to disk (so it can be memory-mapped) every 1000 rows/samples. You can control this with the `writer_batch_size` parameter. Also, when working with fixed-size arrays, the `ArrayXD` feature types yield better performance (e.g., in your case, `features=datasets.Features({"i": datasets.Array3D(shape=(512,512,3), dtype="float32")})` should be faster).
> 
> Our support for multi-dim arrays could be better, and we plan to improve it as part of #5272.

Thanks for the explanation! The Image array was just for demonstration, I use PIL Images in practice. Does that make a difference? What's the best approach for a dataset with PIL Images as rows?

It's best to use the `datasets.Image()` feature type for PIL images (to save space) :)
Add KLUE-MRC metrics
State: closed

## Metrics for KLUE-MRC (Korean Language Understanding Evaluation — Machine Reading Comprehension)

Adding metrics for [KLUE-MRC](https://huggingface.co/datasets/klue).
KLUE-MRC is very similar to SQuAD 2.0 but has a slightly different format which is why I added metrics for KLUE-MRC.

Specifically, in the case of [LM Eval Harness](https://github.com/EleutherAI/lm-evaluation-harness), it leverages the scoring script of SQuAD to evaluate SQuAD 2.0 and KorQuAD. But the script isn't suitable for KLUE-MRC because KLUE-MRC is a bit different from SQuAD 2.0. And this is why I added the scoring script for KLUE-MRC.

- [x] All tests passed
- [x] Added a metric card (referred the metric card of SQuAD 2.0)
- [x] Compatibility test with [LM Eval Harness](https://github.com/EleutherAI/lm-evaluation-harness) passed

### References
- [KLUE: Korean Language Understanding Evaluation](https://datasets-benchmarks-proceedings.neurips.cc/paper_files/paper/2021/file/98dce83da57b0395e163467c9dae521b-Paper-round2.pdf)
- [KLUE on Hugging Face Datasets](https://huggingface.co/datasets/klue)
- #2416

The metrics API in `datasets` is deprecated as of version 2.0, and `evaulate` is our new library for metrics. You can add a new metric to it by following [these steps](https://huggingface.co/docs/evaluate/creating_and_sharing).
Getting a 409 error while loading xglue dataset
State: closed

### Describe the bug

Unable to load xglue dataset

### Steps to reproduce the bug

```python
import datasets

dataset = datasets.load_dataset("xglue", "ntg")
```

> ConnectionError: Couldn't reach https://xglue.blob.core.windows.net/xglue/xglue_full_dataset.tar.gz (error 409)

### Expected behavior

Expected the dataset to load

### Environment info

- `datasets` version: 2.13.1
- Platform: Linux-5.15.107+-x86_64-with-glibc2.31
- Python version: 3.10.12
- Huggingface_hub version: 0.15.1
- PyArrow version: 9.0.0
- Pandas version: 1.5.3

Thanks for reporting, @Praful932.

Let's continue the conversation on the Hub: https://huggingface.co/datasets/xglue/discussions/5
The current implementation has a potential bug in the sort method
State: closed

### Describe the bug

In the sort method，here's a piece of code

```python
# column_names: Union[str, Sequence_[str]]

# Check proper format of and for duplicates in column_names
if not isinstance(column_names, list):
    column_names = [column_names]
```

I get an error when I pass in a tuple based on the column_names type annotation, it will raise an errror.As in the example below, while the type annotation implies that a tuple can be passed.

```python
from datasets import load_dataset

dataset = load_dataset('glue', 'ax')['test']
dataset.sort(column_names=('premise', 'hypothesis'))
# Raise ValueError: Column '('premise', 'hypothesis')' not found in the dataset.
```

Of course, after I modified the tuple into a list, everything worked fine

Change the code to the following so there will be no problem

```python
# Check proper format of and for duplicates in column_names
if not isinstance(column_names, list):
    if isinstance(column_names, str):
        column_names = [column_names]
    else:
        column_names = list(column_names)
```

### Steps to reproduce the bug

```python
from datasets import load_dataset

dataset = load_dataset('glue', 'ax')['test']
dataset.sort(column_names=('premise', 'hypothesis'))
# Raise ValueError: Column '('premise', 'hypothesis')' not found in the dataset.
```

### Expected behavior

Passing tuple into column_names should be equivalent to passing list

### Environment info

- `datasets` version: 2.13.0
- Platform: macOS-13.1-arm64-arm-64bit
- Python version: 3.10.11
- Huggingface_hub version: 0.15.1
- PyArrow version: 12.0.1
- Pandas version: 2.0.2

Thanks for reporting, @wangyuxinwhy.
ValueError: Table schema does not match schema used to create file
State: closed

### Describe the bug

Saving a dataset as parquet fails with a `ValueError: Table schema does not match schema used to create file`  if the dataset was obtained out of a `.select_columns()` call with columns selected out of order.

### Steps to reproduce the bug

```python
import datasets

dataset = datasets.Dataset.from_dict(
    {
        "x1": [1, 2, 3],
        "x2": [10, 11, 12],
    }
)

ds = dataset.select_columns(["x2", "x1"])

ds.to_parquet("demo.parquet")
```

```shell
>>>
ValueError: Table schema does not match schema used to create file: 
table:
x2: int64
x1: int64
-- schema metadata --
huggingface: '{"info": {"features": {"x2": {"dtype": "int64", "_type": "V' + 53 vs. 
file:
x1: int64
x2: int64
-- schema metadata --
huggingface: '{"info": {"features": {"x1": {"dtype": "int64", "_type": "V' + 53
```

--- 

I think this is because after the `.select_columns()` call with out of order columns, the output dataset features' schema ends up being out of sync with the schema of the arrow table backing it. 

```python
ds.features.arrow_schema
>>>
x1: int64
x2: int64
-- schema metadata --
huggingface: '{"info": {"features": {"x1": {"dtype": "int64", "_type": "V' + 53

ds.data.schema
>>>
x2: int64
x1: int64
-- schema metadata --
huggingface: '{"info": {"features": {"x2": {"dtype": "int64", "_type": "V' + 53
```


So when we call `.to_parquet()`, the call behind the scenes to `datasets.io.parquet.ParquetDatasetWriter(...).write()` which initialises the backend `pyarrow.parquet.ParquetWriter` with `schema = self.dataset.features.arrow_schema` triggers `pyarrow` on write when [it checks](https://github.com/apache/arrow/blob/11b140a734a516e436adaddaeb35d23f30dcce44/python/pyarrow/parquet/core.py#L1086-L1090) that the `ParquetWriter` schema matches the schema of the table being written 🙌 

https://github.com/huggingface/datasets/blob/6ed837325cb539a5deb99129e5ad181d0269e050/src/datasets/io/parquet.py#L139-L141


### Expected behavior

The dataset gets successfully saved as parquet. 

*In the same way as it does if saving it as csv:

```python
import datasets

dataset = datasets.Dataset.from_dict(
    {
        "x1": [1, 2, 3],
        "x2": [10, 11, 12],
    }
)

ds = dataset.select_columns(["x2", "x1"])

ds.to_csv("demo.csv")
```

### Environment info

`python==3.11`
`datasets==2.13.1`


We'll do a new release of `datasets` soon to make the fix available :)

In the meantime you can use `datasets` from source (main)

Thank you very much @lhoestq ! 🚀
`map` with any joblib backend
State: open

We recently enabled the (experimental) parallel backend switch for data download and extraction but not for `map` yet.

Right now we're using our `iflatmap_unordered` implementation for multiprocessing that uses a shared Queue to gather progress updates from the subprocesses and show a progress bar in the main process.

If a Queue implementation that would work on any joblib backend by leveraging the filesystem that is shared among workers, we can have `iflatmap_unordered` for joblib and therefore a `map` with any joblib backend with a progress bar !

Note that the Queue doesn't need to be that optimized though since we can choose a small frequency for progress updates (like 1 update per second).

#self-assign

Hi @lhoestq 👋🏼

I’d like to work on this!

Planning to support progress tracking with `map()` using any joblib backend (like "loky") by replacing the Queue-based approach in `iflatmap_unordered` with a file-based progress tracking mechanism (e.g. shared temp file with periodic updates).

This would allow the progress bar to work even in backends where inter-process Queues aren't supported. Let me know if this sounds good — I’ll get started!


I think ideally it should have a general solution, since some joblib backends don't have a shared filesystem
Set a rule on the config and split names
State: open

> should we actually allow characters like spaces? maybe it's better to add validation for whitespace symbols and directly in datasets and raise

https://github.com/huggingface/datasets-server/issues/853


in this case we need to decide what to do with the existing datasets with white space characters (there shouldn't be a lot of them I think)

I imagine that we should stop supporting them, and help the user fix them?

See a report where the datasets server fails: https://huggingface.co/datasets/poloclub/diffusiondb/discussions/2#6374ff55b93cbdf65675f564

The config name is `random_10k [2m]`!
ConnectionError: Couldn't reach dataset_infos.json 
State: closed

### Describe the bug

I'm trying to load codeparrot/codeparrot-clean-train, but get the following error:

ConnectionError: Couldn't reach https://huggingface.co/datasets/codeparrot/codeparrot-clean-train/resolve/main/dataset_infos.json (ConnectionError(ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))))



### Steps to reproduce the bug

train_data = load_dataset('codeparrot/codeparrot-clean-train', split='train')


### Expected behavior

download the dataset

### Environment info

centos7

Unfortunately, I can't reproduce the error. What does the following code return for you?
```python
import requests
from huggingface_hub import hf_hub_url
r = requests.get(hf_hub_url("codeparrot/codeparrot-clean-train", "dataset_infos.json", repo_type="dataset"))
```

Also, can you provide more info about your network (region, proxies, etc.)?
Why max_shard_size is not supported in load_dataset and passed to download_and_prepare
State: closed

### Describe the bug

https://github.com/huggingface/datasets/blob/a8a797cc92e860c8d0df71e0aa826f4d2690713e/src/datasets/load.py#L1809

What I can to is break the `load_dataset` and use `load_datset_builder` + `download_and_prepare` instead.

### Steps to reproduce the bug

https://github.com/huggingface/datasets/blob/a8a797cc92e860c8d0df71e0aa826f4d2690713e/src/datasets/load.py#L1809

### Expected behavior

Users can define the max shard size.

### Environment info

datasets==2.13.1

Can you explain your use case for `max_shard_size`? 

On some systems, there is a limit to the size of a memory-mapped file, so we could consider exposing this parameter in `load_dataset`.

In my use case, users may choose a proper size to balance the cost and benefit of using large shard size. (On azure blob or hdfs which may automatically download the shard from background)

But `load_dataset` doesn't support caching (and reading) Arrow datasets from remote storage. 

`load_datset_builder` + `download_and_prepare` is not equal to `load_dataset`. The latter has one more step, `builder.as_dataset`, that memory-maps Arrow files, which only works for local files.

Thanks. So if I want to use `IterableDataset` and control the size of single arrow file, how should I organize the data loader? Maybe `load_dataset_build` + `download_and_prepare` + `builder.as_dataset` + `dataset.to_iterable_dataset`?

Yes, this should work.

I think we can expose `max_shard_size` in `load_dataset`, so feel free to open a PR.
404 on Datasets Documentation Page
State: closed

### Describe the bug

Getting a 404 from the Hugging Face Datasets docs page:
https://huggingface.co/docs/datasets/index


### Steps to reproduce the bug

1. Go to URL https://huggingface.co/docs/datasets/index
2. Notice 404 not found

### Expected behavior

URL should either show docs or redirect to new location

### Environment info

hugginface.co

This wasn’t working for me a bit earlier, but it looks to be back up now

We had a minor issue updating the docs after the latest release. It should work now :).
Only two cores are getting used in sagemaker with pytorch 3.10 kernel
State: closed

### Describe the bug

When using the newer pytorch 3.10 kernel, only 2 cores are being used by huggingface filter and map functions.  The Pytorch 3.9 kernel would use as many cores as specified in the num_proc field.

We have solved this in our own code by placing the following snippet in the code that is called inside subprocesses:

```os.sched_setaffinity(0, {i for i in range(1000)})```

The problem, as near as we can tell, us that once upon a time, cpu affinity was set using a bitmask ("0xfffff" and the like), and affinity recently changed to a list of processors rather than to using the mask.  As such, only processors 1 and 17 are shown to be working in htop.
![Selection_072](https://github.com/huggingface/datasets/assets/107141022/04c5a824-5321-4531-afca-7bc84dff36b4)


When running functions via `map`, the above resetting of affinity works to spread across the cores.  When using `filter`, however, only two cores are active.

### Steps to reproduce the bug

Repro steps:

1.  Create an aws sagemaker instance
2. use the pytorch 3_10 kernel
3. Load a dataset
4. run a filter operation
5. watch as only 2 cores are used when num_proc > 2
6. run a map operation
7. watch as only 2 cores are used when num_proc > 2
8. run a map operation with processor affinity reset inside the function called via map
9. Watch as all cores run



### Expected behavior

All specified cores are used via the num_proc argument.

### Environment info

AWS sagemaker with the following init script run in the terminal after instance creation:

conda init bash
bash
conda activate pytorch_p310
pip install Wand PyPDF pytesseract datasets seqeval pdfplumber transformers pymupdf sentencepiece timm donut-python accelerate optimum xgboost
python -m pip install 'git+https://github.com/facebookresearch/detectron2.git'
sudo yum -y install htop
sudo yum -y update
sudo yum -y install wget libstdc++ autoconf automake libtool autoconf-archive pkg-config gcc gcc-c++ make libjpeg-devel libpng-devel libtiff-devel zlib-devel

I think it's more likely that this issue is related to PyTorch than Datasets, as PyTorch (on import) registers functions to execute when forking a process. Maybe this is the culprit: https://github.com/pytorch/pytorch/issues/99625

From reading that ticket, it may be down in mkl?  Is it worth hotfixing in the meantime, with the express intention of turning it off?  I know that's a horribly crufty solution, but it's also deeply frustrating to be limited to 2 cores for operations as simple as filtration.

This is too specific and unrelated to `datasets`, so this shouldn't be fixed here.

@mariosasko @mmr-crexi  I had the exact same problem on my kubernetes cluster. the datasets subprocess only user 1 and 17 core
Viewing dataset card returns “502 Bad Gateway”
State: closed

The url is: https://huggingface.co/datasets/Confirm-Labs/pile_ngrams_trigrams

I am able to successfully view the “Files and versions” tab: [Confirm-Labs/pile_ngrams_trigrams at main](https://huggingface.co/datasets/Confirm-Labs/pile_ngrams_trigrams/tree/main)

Any help would be appreciated! Thanks! I hope this is the right place to report an issue like this.


Can you try again? Maybe there was a minor outage.

Yes, it seems to be working now. In case it's helpful, the outage lasted several days. It was failing as late as yesterday morning. 

we fixed something on the server side, glad it's fixed now
Docs: make "repository structure" easier to find
State: open

The page https://huggingface.co/docs/datasets/repository_structure explains how to create a simple repository structure without a dataset script.
It's the simplest way to create a dataset and should be easier to find, particularly on the docs' first pages.

Loading a local dataset also works the same way when `data_files` are not specified, so I agree we should make this info  easier to discover 

cc @stevhliu 

Is this issue open? If so, I will self assign. 

@benjaminbrown038 Yes, it is. Maybe @stevhliu can give some pointers on improving this doc page's discoverability.

I think we can add a version of the [Main use-case](https://huggingface.co/docs/datasets/repository_structure#main-usecase) section to the [Share a dataset to the Hub](https://huggingface.co/docs/datasets/upload_dataset) tutorial. 

Currently, it doesn't tell you *how* to structure the repository; it only tells you how to create it. So adding the "main use-case" will help bridge the gap and make it easier to find. We should also add a link to the [Structure your repository](https://huggingface.co/docs/datasets/repository_structure) guide for users who want to learn about the other options.

#self-assign
Config name / split name lost after map with multiproc
State: open

### Describe the bug

Performing a `.map` method on a dataset loses it's config name / split name only if run with multiproc

### Steps to reproduce the bug

```python
from datasets import Audio, load_dataset
from transformers import AutoFeatureExtractor
import numpy as np

# load dummy dataset
libri = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean")

# make train / test splits
libri = libri["validation"].train_test_split(seed=42, shuffle=True, test_size=0.1)

# example feature extractor
model_id = "ntu-spml/distilhubert"
feature_extractor = AutoFeatureExtractor.from_pretrained(model_id, do_normalize=True, return_attention_mask=True)

sampling_rate = feature_extractor.sampling_rate

libri = libri.cast_column("audio", Audio(sampling_rate=sampling_rate))

max_duration = 30.0

def preprocess_function(examples):
    audio_arrays = [x["array"] for x in examples["audio"]]
    inputs = feature_extractor(
        audio_arrays,
        sampling_rate=feature_extractor.sampling_rate,
        max_length=int(feature_extractor.sampling_rate * max_duration),
        truncation=True,
        return_attention_mask=True,
    )
    return inputs

# single proc map
libri_encoded = libri.map(
    preprocess_function, remove_columns=["audio", "file"], batched=True, num_proc=1
)

print(10 * "=" ,"Single processing", 10 * "=")
print("Config name before: ", libri["train"].config_name, " Split name before: ", libri["train"].split)
print("Config name after: ", libri_encoded["train"].config_name, " Split name after: ", libri_encoded["train"].split)

# multi proc map
libri_encoded = libri.map(
    preprocess_function, remove_columns=["audio", "file"], batched=True, num_proc=2
)

print(10 * "=" ,"Multi processing", 10 * "=")
print("Config name before: ", libri["train"].config_name, " Split name before: ", libri["train"].split)
print("Config name after: ", libri_encoded["train"].config_name, " Split name after: ", libri_encoded["train"].split)
```

**Print Output:**
```
========== Single processing ==========
Config name before:  clean  Split name before:  validation
Config name after:  clean  Split name after:  validation
========== Multi processing ==========
Config name before:  clean  Split name before:  validation
Config name after:  None  Split name after:  None
```

=> we can see that the config/split names are lost in the multiprocessing setting




### Expected behavior

Should retain both config / split names in the multiproc setting

### Environment info

- `datasets` version: 2.13.1.dev0
- Platform: Linux-5.15.0-67-generic-x86_64-with-glibc2.35
- Python version: 3.10.6
- Huggingface_hub version: 0.15.1
- PyArrow version: 12.0.0
- Pandas version: 2.0.2

This must be due to DatasetInfo.from_merge which drops them and is used in `concatenate_datasets`.

And you're experiencing this issue because multiprocessing does concatenate the resulting datasets from each process.

Maybe they should be kept if all the subdatasets share the same values for config_name and split

That sounds like a clean workaround!
IterableDataset: split by node and map may preprocess samples that will be skipped anyway
State: open

              There are two ways an iterable dataset can be split by node:
1. if the number of shards is a factor of number of GPUs: in that case the shards are evenly distributed per GPU
2. otherwise, each GPU iterate on the data and at the end keeps 1 sample out of n(GPUs) - skipping the others.

In case 2. it's therefore possible to have the same examples passed to `prepare_dataset` for each GPU.

This doesn't sound optimized though, because it runs the preprocessing on samples that won't be used in the end.

Could you open a new issue so that we can discuss about this and find a solution ?

_Originally posted by @lhoestq in https://github.com/huggingface/datasets/issues/5360#issuecomment-1592729051_
            

Does "number of shards" refer to the total number of data?

my config:
nproc_per_node=2
ds=ds['train'] = load_dataset(streaming=True).take(50000)

I'm test again: in prepare_data(),  data have the same for each GPU


The number of shards is `ds.n_shards`. It corresponds generally to the number of files the dataset is made of, to be able to distribute to several nodes.

**You don't end up with the same data per GPU**. But all the samples are going through your preprocessing function you pass to map. They are just skipped afterwards to only keep 1 sample out of n(GPUs)

For each GPU, although see the same data in prepare_data(), the actual training data will not be the same in the end. 
Is my understanding correct?

Where can I print the actual training data for each GPU?

> For each GPU, although see the same data in prepare_data(), the actual training data will not be the same in the end.
Is my understanding correct?

Yes exactly :)

> Where can I print the actual training data for each GPU?

You should call print in the data_collator

I print out n_shards, and under multiple GPUs, this value is always 1.
Is this value correct?

Yes it's correct, and it explains why you always have the same data passed to your map function (the data can't be split).

But after being passed to `map`, each GPU keeps one example out of n(GPUs) so that you don't end up with duplicate data across GPUs

> > For each GPU, although see the same data in prepare_data(), the actual training data will not be the same in the end.
> > Is my understanding correct?
> 
> Yes exactly :)
> 
> > Where can I print the actual training data for each GPU?
> 
> You should call print in the data_collator

OK, when printing the train data in the data collator, each GPU sees different data.

Thanks for your reply

Do we have a solution for this one? Or it's required to get "number of shards is a factor of number of GPUs: in that case the shards are evenly distributed per GPU"

For now it's required to have a number of shards that is a factor of the number of GPUs to not have all the workers process the same data (and then skip the right ones to not end up training on duplicate data).

It would be quite complex to implement a strategy that would utilize all the GPUs with an arbitrary number of shards even at the end of training
read metric glue.py from local file 
State: closed

### Describe the bug

Currently, The server is off-line.  I am using the glue metric from the local file downloaded from the hub. 
I download / cached datasets using `load_dataset('glue','sst2', cache_dir='/xxx')` to cache them and then in the off-line mode, I use `load_dataset('xxx/glue.py','sst2', cache_dir='/xxx')`. I can successfully reuse cached datasets.

My problem is about the load_metric. 
When I run `load_dataset('xxx/glue_metric.py','sst2',cache_dir='/xxx')` , it returns 

`  File "xx/lib64/python3.9/site-packages/datasets/utils/deprecation_utils.py", line 46, in wrapper
    return deprecated_function(*args, **kwargs)
  File "xx//lib64/python3.9/site-packages/datasets/load.py", line 1392, in load_metric
    metric = metric_cls(
TypeError: 'NoneType' object is not callable`

Thanks in advance for help! 
### Steps to reproduce the bug

N/A

### Expected behavior

N/A

### Environment info

`datasets == 2.12.0`

Sorry, I solve this by call `evaluate.load('glue_metric.py','sst-2')`
What is the Right way to use discofuse dataset??
State: closed

[Click here for Dataset link](https://huggingface.co/datasets/discofuse/viewer/discofuse-wikipedia/train?row=6)
**Below is the following way, as per my understanding , Is it correct :question: :question:**

The **columns/features from `DiscoFuse dataset`** that will be the **input to the `encoder` and `decoder`** are:

[Click here for Dataset link](https://huggingface.co/datasets/discofuse/viewer/discofuse-wikipedia/train?row=6)

1. **coherent_first_sentence**

2. **coherent_second_sentence**

3. **incoherent_first_sentence**

4. **incoherent_second_sentence**

[Click here for Dataset link](https://huggingface.co/datasets/discofuse/viewer/discofuse-wikipedia/train?row=6)

The **`encoder` will take these four columns as input and encode them into a sequence of hidden states. The `decoder` will then take these hidden states as input and decode them into a new sentence that fuses the two original sentences together.**

The **discourse type, connective_string, has_coref_type_pronoun, and has_coref_type_nominal columns will not be used as input to the encoder or decoder.** These columns are used to provide additional information about the dataset, but they are not necessary for the task of sentence fusion.

Please correct me if I am wrong; otherwise, if this understanding is right, how shall I implement this task practically?

Thanks for opening https://huggingface.co/datasets/discofuse/discussions/3, let's continue the discussion over there if you don't mind

I have posted there also sir, please check
@lhoestq
Return the audio filename when decoding fails due to corrupt files
State: open

### Feature request

Return the audio filename when the audio decoding fails. Although currently there are some checks for mp3 and opus formats with the library version there are still cases when the audio decoding could fail, eg. Corrupt file. 

### Motivation

When you try to load an object file dataset and the decoding fails you can't know which file is corrupt
```

raise LibsndfileError(err, prefix="Error opening {0!r}: ".format(self.name))
soundfile.LibsndfileError: Error opening <_io.BytesIO object at 0x7f5ab7e38290>: Format not recognised.
```

### Your contribution

Make a PR to Add exceptions for LIbsndfileError to return the audio filename or path when soundfile decoding fails.

Hi ! The audio data don't always exist as files on disk - the blobs are often stored in the Arrow files. For now I'd suggest disabling decoding with `.cast_column("audio", Audio(decode=False))` and apply your own decoding that handles corrupted files (maybe to filter them out ?)

cc @sanchit-gandhi since it's related to our discussion about allowing users to make decoding return `None` and show a warning when there are corrupted files

Thanks @lhoestq, I wasn't aware of the decode flag. It makes more sense as you say to show a warning when there are corrupted files together with some metadata of the file that allows to filter them from the dataset.

My workaround was to catch the LibsndfileError and generate a dummy audio with an unsual sample rate to filter it later. However returning `None` seems better. 

`try:
    array, sampling_rate = sf.read(file)
except sf.LibsndfileError:
    print("bad file")
    array = np.array([0.0])
    sampling_rate = 99.000`
Failing to upload dataset to the hub
State: closed

### Describe the bug

Trying to upload a dataset of hundreds of thousands of audio samples (the total volume is not very large, 60 gb) to the hub with push_to_hub, it doesn't work.
From time to time one piece of the data (parquet) gets pushed and then I get RemoteDisconnected even though my internet is stable.
Please help.
I'm trying to upload the dataset for almost a week.
Thanks

### Steps to reproduce the bug

not relevant 

### Expected behavior

Be able to upload thedataset

### Environment info

python: 3.9

Hi ! Feel free to re-run your code later, it will resume automatically where you left

Tried many times in the last 2 weeks, problem remains.

Alternatively you can save your dataset in parquet files locally and upload them to the hub manually

```python
from tqdm import tqdm
num_shards = 60
for index in tqdm(range(num_shards)):
    ds.shard(num_shards=num_shards, index=index, contiguous=True).to_parquet(f"{index:05d}.parquet")
````
`datasets.map` not reusing cached copy by default
State: closed

### Describe the bug

When I load the dataset from local directory, it's cached copy is picked up after first time. However, for `map` operation, the operation is applied again and cached copy is not picked up. Is there any way to pick cached copy instead of processing it again? The only solution I could think of was to use `save_to_disk` after my last transform and then use that in my DataLoader pipeline. Are there any other solutions for the same?

One more thing, my dataset is occupying 6GB storage memory after I use `map`, is there any way I can reduce that memory usage?


### Steps to reproduce the bug

```
# make sure that dataset decodes audio with correct sampling rate
dataset_sampling_rate = next(iter(self.raw_datasets.values())).features["audio"].sampling_rate
if dataset_sampling_rate != self.feature_extractor.sampling_rate:
    self.raw_datasets = self.raw_datasets.cast_column(
        "audio", datasets.features.Audio(sampling_rate=self.feature_extractor.sampling_rate)
    )

vectorized_datasets = self.raw_datasets.map(
    self.prepare_dataset,
    remove_columns=next(iter(self.raw_datasets.values())).column_names,
    num_proc=self.num_workers,
    desc="preprocess datasets",
)
# filter data that is longer than max_input_length
self.vectorized_datasets = vectorized_datasets.filter(
    self.is_audio_in_length_range,
    num_proc=self.num_workers,
    input_columns=["input_length"],
        )

def prepare_dataset(self, batch):
    # load audio
    sample = batch["audio"]
    inputs = self.feature_extractor(sample["array"], sampling_rate=sample["sampling_rate"])
    batch["input_values"] = inputs.input_values[0]
    batch["input_length"] = len(batch["input_values"])

    batch["labels"] = self.tokenizer(batch["target_text"]).input_ids
    return batch

```

### Expected behavior

`map` to use cached copy and if possible an alternative technique to reduce memory usage after using `map`

### Environment info


- `datasets` version: 2.12.0
- Platform: Linux-3.10.0-1160.71.1.el7.x86_64-x86_64-with-glibc2.17
- Python version: 3.8.16
- Huggingface_hub version: 0.15.1
- PyArrow version: 12.0.0
- Pandas version: 2.0.2


This can happen when a map transform cannot be hashed deterministically (e.g., an object referenced by the transform changes its state after the first call - an issue with fast tokenizers). The solution is to provide `cache_file_name` in the `map` call to check this file for the cached result instead of relying on the default caching mechanism.
Importing PyTorch reduces multiprocessing performance for map
State: closed

### Describe the bug

I noticed that the performance of my dataset preprocessing with `map(...,num_proc=32)` decreases when PyTorch is imported.

### Steps to reproduce the bug

I created two example scripts to reproduce this behavior:

```
import datasets
datasets.disable_caching()

from datasets import Dataset
import time
    
PROC=32

if __name__ == "__main__":
    dataset = [True] * 10000000
    dataset = Dataset.from_dict({'train': dataset})
    

    start = time.time()
    dataset.map(lambda x: x, num_proc=PROC)
    end = time.time()
    print(end - start)
```
Takes around 4 seconds on my machine.

While the same code, but with an `import torch`:
```
import datasets
datasets.disable_caching()

from datasets import Dataset
import time
import torch
    
PROC=32

if __name__ == "__main__":
    dataset = [True] * 10000000
    dataset = Dataset.from_dict({'train': dataset})
    

    start = time.time()
    dataset.map(lambda x: x, num_proc=PROC)
    end = time.time()
    print(end - start)
```
takes around 22 seconds.



### Expected behavior

I would expect that the import of torch to not have such a significant effect on the performance of map using multiprocessing.


### Environment info

- `datasets` version: 2.12.0
- Platform: Linux-5.15.0-56-generic-x86_64-with-glibc2.35
- Python version: 3.11.3
- Huggingface_hub version: 0.15.1
- PyArrow version: 12.0.0
- Pandas version: 2.0.2
- torch: 2.0.1

Hi! The times match when I run this code locally or on Colab.

Also, we use `multiprocess`, not `multiprocessing`, for parallelization, and torch's `__init__.py` (executed on `import torch` ) slightly modifies the latter.

Hey Mariosasko,

Thanks for looking into it. We further did some investigations after your comment and figured out it's only affecting some hardware/software configurations with the `pytorch` installation of `conda-forge`. Based on this we found the following issue in PyTorch: https://github.com/pytorch/pytorch/issues/102269 with a quick fix for now.

Since it seems to be a deeper issue with forking processes, the difference between`multiprocess` and `multiprocessing` didn't make a difference.

Closing this, since the issue comes from `pytorch` not `dataset`.
Length of table does not accurately reflect the split
State: closed

### Describe the bug

I load a Huggingface Dataset and do `train_test_split`. I'm expecting the underlying table for the dataset to also be split, but it's not.

### Steps to reproduce the bug

![image](https://github.com/huggingface/datasets/assets/8068268/83e5768f-8b4c-422a-945c-832a7585afff)


### Expected behavior

The expected behavior is when `len(hf_dataset["train"].data)` should match the length of the train split, and not be the entire unsplit dataset.

### Environment info

datasets 2.10.1
python 3.10.11

As already replied by @lhoestq (private channel):
> `.train_test_split` (as well as `.shard`, `.select`) doesn't create a new arrow table to save time and disk space. Instead, it uses an indices mapping on top of the table that locate which examples are part of train or test.

This is an optimization that we don't plan to "fix", so I'm closing this issue.
File not found for audio dataset
State: open

### Describe the bug

After loading an audio dataset, and looking at a sample entry, the `path` element, which is supposed to be the path to the audio file, doesn't actually exist.


### Steps to reproduce the bug

Run bug.py:

```py
import os.path

from datasets import load_dataset

def run() -> None:
    cv13 = load_dataset(
        "mozilla-foundation/common_voice_13_0",
        "hi",
        split="train",
    )

    print(cv13[0])
    audio_file = cv13[0]["path"]
    if not os.path.exists(audio_file):
        raise ValueError(f'File {audio_file} does not exist.')

if __name__ == "__main__":
    run()
```

The result (on my machine):

```json
{'client_id': '0f018a99663f33afbb7d38aee281fb1afcfd07f9e7acd00383f604e1e17c38d6ed8adf1bd2ccbf927a52c5adefb8ac4b158ce27a7c2ed9581e71202eb302dfb3', 'path': 'C:\\Users\\rober\\.cache\\huggingface\\datasets\\downloads\\extracted\\8d1479bc09b4609bc2675bd02d6869a4d5e09f7e6616f540bd55eacef46c6e2b\\common_voice_hi_26008353.mp3', 'audio': {'path': 'C:\\Users\\rober\\.cache\\huggingface\\datasets\\downloads\\extracted\\8d1479bc09b4609bc2675bd02d6869a4d5e09f7e6616f540bd55eacef46c6e2b\\common_voice_hi_26008353.mp3', 'array': array([ 6.46234854e-26, -1.35709319e-25, -8.07793567e-26, ...,
        1.06425944e-07,  4.46417090e-08,  2.61451660e-09]), 'sampling_rate': 48000}, 'sentence': 'हमने उसका जन्मदिन मनाया।', 'up_votes': 2, 'down_votes': 0, 'age': '', 'gender': '', 'accent': '', 'locale': 'hi', 'segment': '' ', 'variant': ''}
```

```txt
Traceback (most recent call last):
  File "F:\eo-reco\bug.py", line 18, in <module>
    run()
  File "F:\eo-reco\bug.py", line 15, in run
    raise ValueError(f'File {audio_file} does not exist.')
ValueError: File C:\Users\rober\.cache\huggingface\datasets\downloads\extracted\8d1479bc09b4609bc2675bd02d6869a4d5e09f7e6616f540bd55eacef46c6e2b\common_voice_hi_26008353.mp3 does not exist.
```


### Expected behavior

The `path` element points to the correct file, which happens to be:

```
C:\Users\rober\.cache\huggingface\datasets\downloads\extracted\8d1479bc09b4609bc2675bd02d6869a4d5e09f7e6616f540bd55eacef46c6e2b\hi_train_0\common_voice_hi_26008353.mp3
```

That is, there's an extra directory `hi_train_0` that is not in the `path` element.


### Environment info

- `datasets` version: 2.12.0
- Platform: Windows-10-10.0.22621-SP0
- Python version: 3.11.3
- Huggingface_hub version: 0.14.1
- PyArrow version: 12.0.0
- Pandas version: 2.0.1
- 

load_dataset () did not work for loading local files either
I tried to load a custom dataset using the following statement: dataset = load_dataset('json', data_files=data_files). The dataset contains 50 million text-image pairs, but an error occurred.
State: closed

### Describe the bug

File "/home/kas/.conda/envs/diffusers/lib/python3.7/site-packages/datasets/builder.py", line 1858, in _prepare_split_single
Downloading and preparing dataset json/default to /home/kas/diffusers/examples/dreambooth/cache_data/datasets/json/default-acf423d8c6ef99d0/0.0.0/e347ab1c932092252e717ff3f949105a4dd28b27e842dd53157d2f72e276c2e4...
Downloading data files: 0%| | 0/1 [00:00<?, ?it/s] Downloading data files: 100%|██████████| 1/1 [00:00<00:00, 84.35it/s]
Extracting data files: 0%| | 0/1 [00:00<?, ?it/s] for _, table in generator:
File "/home/kas/.conda/envs/diffusers/lib/python3.7/site-packages/datasets/packaged_modules/json/json.py", line 114, in _generate_tables
io.BytesIO(batch), read_options=paj.ReadOptions(block_size=block_size)
File "pyarrow/_json.pyx", line 258, in pyarrow._json.read_json
Extracting data files: 100%|██████████| 1/1 [00:00<00:00, 27.72it/s]
Generating train split: 0 examples [00:00, ? examples/s] File "pyarrow/error.pxi", line 144, in pyarrow.lib.pyarrow_internal_check_status
File "pyarrow/error.pxi", line 125, in pyarrow.lib.check_status
pyarrow.lib.ArrowCapacityError: array cannot contain more than 2147483646 bytes, have 2390448764

### Steps to reproduce the bug

1、data_files = ["1.json", "2.json", "3.json"]
2、dataset = load_dataset('json', data_files=data_files)

### Expected behavior

Read the dataset normally.



### Environment info

- `datasets` version: 2.12.0
- Platform: Linux-4.15.0-29-generic-x86_64-with-debian-buster-sid
- Python version: 3.7.16
- Huggingface_hub version: 0.14.1
- PyArrow version: 12.0.0
- Pandas version: 1.3.5

Thanks for reporting, @cjt222.

What is the structure of your JSON files. Please note that it is normally simpler if the data file format is JSON-Lines instead. 

> Thanks for reporting, @cjt222.
> 
> What is the structure of your JSON files. Please note that it is normally simpler if the data file format is JSON-Lines instead.

Thanks! I have encountered similar problems. I modify the json format from list to line and works!