polars.DataFrame.merge_sorted#
- DataFrame.merge_sorted(
- other: DataFrame,
- key: str,
Take two sorted DataFrames and merge them by the sorted key.
The output of this operation will also be sorted. It is the callers responsibility that the frames are sorted by that key otherwise the output will not make sense.
The schemas of both DataFrames must be equal.
- Parameters:
- other
Other DataFrame that must be merged
- key
Key that is sorted.
Notes
No guarantee is given over the output row order when the key is equal between the both dataframes.
Examples
>>> df0 = pl.DataFrame( ... {"name": ["steve", "elise", "bob"], "age": [42, 44, 18]} ... ).sort("age") >>> df0 shape: (3, 2) ┌───────┬─────┐ │ name ┆ age │ │ --- ┆ --- │ │ str ┆ i64 │ ╞═══════╪═════╡ │ bob ┆ 18 │ │ steve ┆ 42 │ │ elise ┆ 44 │ └───────┴─────┘ >>> df1 = pl.DataFrame( ... {"name": ["anna", "megan", "steve", "thomas"], "age": [21, 33, 42, 20]} ... ).sort("age") >>> df1 shape: (4, 2) ┌────────┬─────┐ │ name ┆ age │ │ --- ┆ --- │ │ str ┆ i64 │ ╞════════╪═════╡ │ thomas ┆ 20 │ │ anna ┆ 21 │ │ megan ┆ 33 │ │ steve ┆ 42 │ └────────┴─────┘ >>> df0.merge_sorted(df1, key="age") shape: (7, 2) ┌────────┬─────┐ │ name ┆ age │ │ --- ┆ --- │ │ str ┆ i64 │ ╞════════╪═════╡ │ bob ┆ 18 │ │ thomas ┆ 20 │ │ anna ┆ 21 │ │ megan ┆ 33 │ │ steve ┆ 42 │ │ steve ┆ 42 │ │ elise ┆ 44 │ └────────┴─────┘