Add Expr.list.map_elements(func) to perform a custom function on every element in a list

[DeflateAwning]

Description

Add Expr.list.map_elements(func) to perform a custom function on every element in a list

[cmdlineluser]

It is accessible via list.eval()

s = pl.Series([[1, 2, 3]])

s.list.eval(   
    pl.element().map_elements(lambda n: 
        f"func({n + 1})", 
        return_dtype=pl.String
    )
)

# shape: (1,)
# Series: '' [list[str]]
# [
# 	["func(2)", "func(3)", "func(4)"]
# ]

(But probably a performance destroyer.)

[DeflateAwning]

Would you consider adding it as its own method? Would make it a bit cleaner imo

[MarcoGorelli]

thanks for the request!

per some discussion, this is rejected, you can use eval and pl.element - this is already going to be very inefficient and so doesn't warrant its own method

[cmdlineluser]

map_elements has an issue with exceptions, which is why you didn't get an error:

• map_elements silently swallows Exceptions when return_dtype= is set #19315