how to apply function to nested dataset when nest_by column is needed in function

gistfile1.txt

library(tidyverse)

fun <- function(x) {
    if (any(x$Species == "setosa")) {
        tail(x, n = 3) |> select(Petal.Length)
    } else {
        head(x, n = 3) |> select(Petal.Length)
    }
}


validation_tbl <- iris |>
    group_by(Species) |>
    do(fun(.))


method1_tbl <- iris |> 
    mutate(
        Species2=Species
    ) |> 
    nest_by(Species2) |> 
    mutate(
        fn=list(fun(data))
    ) |> 
    unnest(fn) |> 
    select(
        Species=Species2
        ,Petal.Length
    )

all.equal(validation_tbl,method1_tbl)

fun2 <- function(data,species) {
    if (any(species== "setosa")) {
        tail(data, n = 3) |> select(Petal.Length)
    } else {
        head(data, n = 3) |> select(Petal.Length)
    }
}


method2_tbl <- iris |> 
    nest_by(Species) |> 
    mutate(
        fn=list(fun2(data,Species))
    ) |> 
    unnest(fn) |> 
    select(
        Species
        ,Petal.Length
    )


all.equal(validation_tbl,method2_tbl)


## with map()

fun3 <- function(x) {
    if (any(x$Species == "setosa")) {
        tail(x, n = 3) |> select(Species,Petal.Length)
    } else {
        head(x, n = 3) |> select(Species,Petal.Length)
    }
}


split_tbl <- iris |> 
    group_split(Species)
    

method3_tbl <- map(.x = split_tbl,.f = \(.x) fun3(.x)) |> 
    purrr::list_rbind()




all.equal(validation_tbl |> ungroup(),method3_tbl)