Extending Narwhals
Warning
The extension mechanism in Narwhals is experimental and under development.
If you want your own library to be recognised too, you're welcome open a PR (with tests)!. Alternatively, if you can't do that (for example, if you library is closed-source), see the next section for what else you can do.
We love open source, but we're not "open source absolutists". If you're unable to open source you library, then this is how you can make your library compatible with Narwhals.
Make sure that you also define:
DataFrame.__narwhals_dataframe__
: return an object which implements methods from theCompliantDataFrame
protocol innarwhals/typing.py
.DataFrame.__narwhals_namespace__
: return an object which implements methods from theCompliantNamespace
protocol innarwhals/typing.py
.DataFrame.__native_namespace__
: return the object's native namespace.LazyFrame.__narwhals_lazyframe__
: return an object which implements methods from theCompliantLazyFrame
protocol innarwhals/typing.py
.LazyFrame.__narwhals_namespace__
: return an object which implements methods from theCompliantNamespace
protocol innarwhals/typing.py
.LazyFrame.__native_namespace__
: return the object's native namespace.Series.__narwhals_series__
: return an object which implements methods from theCompliantSeries
protocol innarwhals/typing.py
.
If your library doesn't distinguish between lazy and eager, then it's OK for your dataframe
object to implement both __narwhals_dataframe__
and __narwhals_lazyframe__
. In fact,
that's currently what narwhals._pandas_like.dataframe.PandasLikeDataFrame
does. So, if you're stuck,
take a look at the source code to see how it's done!
Note that this "extension" mechanism is still experimental. If anything is not clear, or doesn't work, please do raise an issue or contact us on Discord (see the link on the README).