narwhals-map 0.1.0

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narwhals-map

An experimental Narwhals plugin adding Map datatype.

[!TIP] See narwhals-dev/narwhals#3525 issue for more info.

Map is natively supported across all backends except for Polars.

Supported Narwhals backends:

• Arrow
• Ibis
• Polars (via polars-map)

Currently monkey-patches Narwhals to expose a new nw.col.map namespace.

Usage

import narwhals as nw
import narwhals_map  # registers the Map dtype and .map namespace

df = nw.from_native(native_df)  # use polars_map.Map for Polars-backed frames
result = df.select(nw.col("map_col").map.get("key1"))

Known Limitations

• .to_arrow() on Polars-backed frames: Polars (via polars-map) stores maps as List(Struct({key, value})) internally. Calling .to_arrow() on a Polars-backed Narwhals frame produces list<struct<key, value>> columns instead of Arrow map types. PyArrow and Ibis backends are unaffected.