Implementation:Huggingface Datasets CsvDatasetReader

Knowledge Sources	Huggingface Datasets HF Datasets Docs
Domains	Data_Engineering, NLP
Last Updated	2026-02-14 18:00 GMT

Overview

Concrete tool for importing CSV files into the HuggingFace Dataset format provided by the HuggingFace Datasets library.

Description

CsvDatasetReader is a reader class that extends AbstractDatasetReader and uses the packaged Csv builder to parse one or more CSV files into an Arrow-backed Dataset or IterableDataset. It supports configurable features, caching, in-memory loading, streaming mode, and multiprocessing. All additional keyword arguments are forwarded to the underlying Csv builder, allowing full control over CSV dialect options (delimiter, quoting, encoding, etc.).

Usage

Use CsvDatasetReader when you need to programmatically load CSV files into a HuggingFace Dataset. It is typically invoked indirectly via Dataset.from_csv() or load_dataset("csv", ...), but can also be instantiated directly for fine-grained control.

Code Reference

Source Location

• Repository: datasets
• File: src/datasets/io/csv.py
• Lines: L15-L66

Signature

class CsvDatasetReader(AbstractDatasetReader):
    def __init__(
        self,
        path_or_paths: NestedDataStructureLike[PathLike],
        split: Optional[NamedSplit] = None,
        features: Optional[Features] = None,
        cache_dir: str = None,
        keep_in_memory: bool = False,
        streaming: bool = False,
        num_proc: Optional[int] = None,
        **kwargs,
    ):

    def read(self):

Import

from datasets.io.csv import CsvDatasetReader

I/O Contract

Inputs

Name	Type	Required	Description
path_or_paths	NestedDataStructureLike[PathLike]	Yes	Path(s) to CSV file(s). Can be a single path, a list of paths, or a dict mapping split names to paths.
split	Optional[NamedSplit]	No	Name of the dataset split to assign to the loaded data.
features	Optional[Features]	No	Explicit schema to apply instead of inferring from the CSV headers and data.
cache_dir	str	No	Directory for caching the processed dataset.
keep_in_memory	bool	No	Whether to keep the dataset in memory instead of memory-mapping. Defaults to False.
streaming	bool	No	If True, returns an IterableDataset for streaming access. Defaults to False.
num_proc	Optional[int]	No	Number of processes for parallel dataset preparation.
**kwargs		No	Additional keyword arguments forwarded to the Csv builder (e.g., delimiter, quoting).

Outputs

Name	Type	Description
dataset	Dataset or IterableDataset	The loaded dataset, either map-style or iterable depending on the streaming parameter.

Usage Examples

Basic Usage

from datasets.io.csv import CsvDatasetReader

# Load a single CSV file
reader = CsvDatasetReader("data/train.csv", split="train")
dataset = reader.read()

# Load with streaming
reader = CsvDatasetReader("data/train.csv", streaming=True)
iterable_dataset = reader.read()

# Load with custom delimiter
reader = CsvDatasetReader("data/train.tsv", split="train", sep="\t")
dataset = reader.read()

Related Pages

Implements Principle

• Principle:Huggingface_Datasets_CSV_Import