full joins withe coalesce

[topofocus]

Recently I switched to the most recent version of this fantastic gem.

However, the compatibility of joins is not perfect.
In Version 0.31 it was possible to perform join ... how: 'outer',

Now it's join ... how: 'full'

Polars performs a full-join with coalesce: false. The result is shown below

┌────────────┬──────────┬─────────────┬───────────┬──────────────────┐
│ datum      ┆ max      ┆ datum_right ┆ reference ┆ reference_border │
│ ---        ┆ ---      ┆ ---         ┆ ---       ┆ ---              │
│ date       ┆ f64      ┆ date        ┆ f64       ┆ i64              │
╞════════════╪══════════╪═════════════╪═══════════╪══════════════════╡
│ 2023-08-31 ┆ 7308.2   ┆ 2023-08-31  ┆ 6600.0    ┆ 6534             │
│ 2023-09-01 ┆ 7305.269 ┆ null        ┆ null      ┆ null             │
│ 2023-09-04 ┆ 7308.6   ┆ null        ┆ null      ┆ null             │
│ 2023-09-05 ┆ 7280.8   ┆ null        ┆ null      ┆ null             │
│ 2023-09-06 ┆ 7264.5   ┆ null        ┆ null      ┆ null             │
│ …          ┆ …        ┆ …           ┆ …         ┆ …                │
│ 2024-10-11 ┆ 8214.9   ┆ null        ┆ null      ┆ null             │
│ 2024-10-14 ┆ 8251.9   ┆ null        ┆ null      ┆ null             │
│ 2024-10-15 ┆ 8314.5   ┆ null        ┆ null      ┆ null             │
│ 2024-10-16 ┆ 8318.37  ┆ null        ┆ null      ┆ null             │
│ null       ┆ null     ┆ 2024-12-19  ┆ 8300.0    ┆ 6534             │
└────────────┴──────────┴─────────────┴───────────┴──────────────────┘

Instead of joining the dataframes on "datum", a datum_right column is added.

According to the python-reference
the parameter coalesce: true resets the behavior to the 'old'-version.

I tried to patch the library, without success so far.

[ankane]

Hi @topofocus, the coalesce option was added in #83 and will be available in the next release.

[topofocus]

Thanks!