Skip to main content

Extremely lightweight compatibility layer between dataframe libraries

Project description

Narwhals

narwhals_small

PyPI version Downloads Trusted publishing PYPI - Types

Extremely lightweight and extensible compatibility layer between dataframe libraries!

  • Full API support: cuDF, Modin, pandas, Polars, PyArrow.
  • Lazy-only support: Daft, Dask, DuckDB, Ibis, PySpark, SQLFrame.

Seamlessly support all, without depending on any!

  • Just use a subset of the Polars API, no need to learn anything new
  • Zero dependencies, Narwhals only uses what the user passes in so your library can stay lightweight
  • ✅ Separate lazy and eager APIs, use expressions
  • ✅ Support pandas' complicated type system and index, without either getting in the way
  • 100% branch coverage, tested against pandas and Polars nightly builds
  • Negligible overhead, see overhead
  • ✅ Let your IDE help you thanks to full static typing, see typing
  • Perfect backwards compatibility policy, see stable api for how to opt-in

Get started!

Table of contents

Installation

  • pip (recommended, as it's the most up-to-date)
    pip install narwhals
    
  • conda-forge (also fine, but the latest version may take longer to appear)
    conda install -c conda-forge narwhals
    

Usage

There are three steps to writing dataframe-agnostic code using Narwhals:

  1. use narwhals.from_native to wrap a pandas/Polars/Modin/cuDF/PyArrow DataFrame/LazyFrame in a Narwhals class

  2. use the subset of the Polars API supported by Narwhals

  3. use narwhals.to_native to return an object to the user in its original dataframe flavour. For example:

    • if you started with pandas, you'll get pandas back
    • if you started with Polars, you'll get Polars back
    • if you started with Modin, you'll get Modin back (and compute will be distributed)
    • if you started with cuDF, you'll get cuDF back (and compute will happen on GPU)
    • if you started with PyArrow, you'll get PyArrow back

narwhals_gif

Example

Narwhals allows you to define dataframe-agnostic functions. For example:

import narwhals as nw
from narwhals.typing import IntoFrameT


def agnostic_function(
    df_native: IntoFrameT,
    date_column: str,
    price_column: str,
) -> IntoFrameT:
    return (
        nw.from_native(df_native)
        .group_by(nw.col(date_column).dt.truncate("1mo"))
        .agg(nw.col(price_column).mean())
        .sort(date_column)
        .to_native()
    )

You can then pass pandas.DataFrame, polars.DataFrame, polars.LazyFrame, duckdb.DuckDBPyRelation, pyspark.sql.DataFrame, pyarrow.Table, and more, to agnostic_function. In each case, no additional dependencies will be required, and computation will stay native to the input library:

import pandas as pd
import polars as pl
from datetime import datetime

data = {
    "date": [datetime(2020, 1, 1), datetime(2020, 1, 8), datetime(2020, 2, 3)],
    "price": [1, 4, 3],
}
print("pandas result:")
print(agnostic_function(pd.DataFrame(data), "date", "price"))
print()
print("Polars result:")
print(agnostic_function(pl.DataFrame(data), "date", "price"))
pandas result:
        date  price
0 2020-01-01    2.5
1 2020-02-01    3.0

Polars result:
shape: (2, 2)
┌─────────────────────┬───────┐
│ date                ┆ price │
│ ---                 ┆ ---   │
│ datetime[μs]        ┆ f64   │
╞═════════════════════╪═══════╡
│ 2020-01-01 00:00:00 ┆ 2.5   │
│ 2020-02-01 00:00:00 ┆ 3.0   │
└─────────────────────┴───────┘

See the tutorial for several examples!

Scope

  • Do you maintain a dataframe-consuming library?
  • Do you have a specific Polars function in mind that you would like Narwhals to have in order to make your work easier?

If you said yes to both, we'd love to hear from you!

Roadmap

See roadmap discussion on GitHub for an up-to-date plan of future work.

Used by

Join the party!

Feel free to add your project to the list if it's missing, and/or chat with us on Discord if you'd like any support.

Sponsors and institutional partners

Narwhals is 100% independent, community-driven, and community-owned. We are extremely grateful to the following organisations for having provided some funding / development time:

If you contribute to Narwhals on your organization's time, please let us know. We'd be happy to add your employer to this list!

Support

If you'd like to say "thank you", please give us a ⭐ star ⭐.

Please contact hello_narwhals@proton.me if you would like to:

  • Receive professional support (e.g., if you're using or would like to use Narwhals at your company).
  • Have any Narwhals fixes / features prioritised.
  • Commission any Narwhals plugins for new backends.

Appears on

Narwhals has been featured in several talks, podcasts, and blog posts:

Why "Narwhals"?

Coz they are so awesome.

Thanks to Olha Urdeichuk for the illustration!

Project details


Release history Release notifications | RSS feed

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

narwhals-2.16.0.tar.gz (618.3 kB view details)

Uploaded Source

Built Distribution

If you're not sure about the file name format, learn more about wheel file names.

narwhals-2.16.0-py3-none-any.whl (444.0 kB view details)

Uploaded Python 3

File details

Details for the file narwhals-2.16.0.tar.gz.

File metadata

  • Download URL: narwhals-2.16.0.tar.gz
  • Upload date:
  • Size: 618.3 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? Yes
  • Uploaded via: twine/6.1.0 CPython/3.13.7

File hashes

Hashes for narwhals-2.16.0.tar.gz
Algorithm Hash digest
SHA256 155bb45132b370941ba0396d123cf9ed192bf25f39c4cea726f2da422ca4e145
MD5 61ceeafea6cbbb43761e696d4e7160be
BLAKE2b-256 fc6f713be67779028d482c6e0f2dde5bc430021b2578a4808c1c9f6d7ad48257

See more details on using hashes here.

Provenance

The following attestation bundles were made for narwhals-2.16.0.tar.gz:

Publisher: publish_to_pypi.yml on narwhals-dev/narwhals

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file narwhals-2.16.0-py3-none-any.whl.

File metadata

  • Download URL: narwhals-2.16.0-py3-none-any.whl
  • Upload date:
  • Size: 444.0 kB
  • Tags: Python 3
  • Uploaded using Trusted Publishing? Yes
  • Uploaded via: twine/6.1.0 CPython/3.13.7

File hashes

Hashes for narwhals-2.16.0-py3-none-any.whl
Algorithm Hash digest
SHA256 846f1fd7093ac69d63526e50732033e86c30ea0026a44d9b23991010c7d1485d
MD5 4ecae7fa47494404e4ed69c937c27138
BLAKE2b-256 03cc7cb74758e6df95e0c4e1253f203b6dd7f348bf2f29cf89e9210a2416d535

See more details on using hashes here.

Provenance

The following attestation bundles were made for narwhals-2.16.0-py3-none-any.whl:

Publisher: publish_to_pypi.yml on narwhals-dev/narwhals

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

Supported by

AWS Cloud computing and Security Sponsor Datadog Monitoring Depot Continuous Integration Fastly CDN Google Download Analytics Pingdom Monitoring Sentry Error logging StatusPage Status page