Julian

`struct.rename_fields` enhancements: correct name count & dict input

6

### Problem description Adjusting struct field names currently is a little weird with `rename_fields` ## Length of `names` parameter ```python rating_Series = pl.Series( "ratings", [ {"Movie": "Cars", "Theatre": "NE", "Avg_Rating":...

Improve string split API and DataTypes (`split`, `splitn`, `split_exact`)

2

### Description I wanted to bring this back once more before "locking in the API" with V1.0 (see also #11640, #13649) ## Example ```python pl.DataFrame({"str": ["hello world !", "a b...

### Checks - [X] I have checked that this issue has not already been reported. - [X] I have confirmed this bug exists on the [latest version](https://pypi.org/project/polars/) of Polars. ###...

Enable `pivot` on LazyFrame and speedup `pivot` on DataFrame

7

### Description I understand that currently `pivot` is not supported for LazyFrame because the schema cannot be known. However, if I know the schema/columns in advance or only want a...

Make `unnest()` "unnest" all columns by default

1

### Description Most of the times in my experience you want to "unnest" ALL of the structs you have or only have 1-2 that you want to unnest. It is...