Altair and Polars Integration: Onboarding Notes

Key Points

• Altair 5+ supports Polars DataFrames natively
• You can pass a polars.DataFrame directly to alt.Chart() without converting to pandas. Example:

import altair as alt
import polars as pl
df = pl.DataFrame({"x": [1, 2], "y": [3, 4]})
chart = alt.Chart(df).mark_line()

• No need for pandas conversion
• Previous versions required df.to_pandas(), but this is no longer necessary.
• This reduces dependencies and improves performance for Polars users.
• Testing with Altair and Polars
• When writing tests for Altair charts, use Polars DataFrames directly.
• Ensure your environment has compatible versions of Altair and Polars.

Additional Notes

• If you encounter errors about data types, check that your Altair version is recent (5.0+).
• For more details, see the Altair documentation.

This file is intended for onboarding AI agents and developers working with Altair and Polars in this codebase.