I have two polars dataframe, one dataframe df_1 with two columns start and end the other dataframe df_2 one with a column dates and I want to do a left join on df_2 under the condition that the dates column is in between the start and end column. To make it more obvious what I want to do here is an example DATA import polars as pl from datetime import date df_1 = pl.DataFrame( { "id": ["abc", "abc", "456"], "start": [date(2022, 1, 1), date(2022, 3, 4), date(2022, 5, 11)], "end": [date(2022, 2, 4), date(2022, 3, 10), date(2022, 5, 16)], "value": [10, 3, 4] } ) df_2 = pl.DataFrame( { "id": ["abc", "abc", "456", "abc", "abc", "456"], "dates": [date(2022, 1, 2), date(2022, 3, 4), date(2022, 5, 11), date(2022, 1, 4), date(2022, 3, 7), date(2022, 5, 13)], } ) So now I would join on id and that dates is in between start and end and the result should look like that RESULT shape: (6, 3) ┌─────┬────────────┬───────┐ │ id ┆ dates ┆ value │ │ --- ┆ --- ┆ --- │ │ str ┆ date ┆ i64 │ ╞═════╪════════════╪═══════╡ │ abc ┆ 2022-01-02 ┆ 10 │ │ abc ┆ 2022-03-04 ┆ 3 │ │ 456 ┆ 2022-05-11 ┆ 4 │ │ abc ┆ 2022-01-04 ┆ 10 │ │ abc ┆ 2022-03-07 ┆ 3 │ │ 456 ┆ 2022-05-13 ┆ 4 │ └─────┴────────────┴───────┘ Continue reading...