R: Transforming variables over many columns - r

Question

I want to transform multiple columns in a large data.frame at once using across.
As an example I want to make this transformation
library(tidyverse)
iris %>% mutate(Sepal.Length2 = (Sepal.Length^4-min(Sepal.Length^4)) / (max(Sepal.Length^4) - min(Sepal.Length^4)))
but for all columns starting with "Sepal".
I think, I can use this command, but I can't figure how I can add my function.
iris %>% mutate(across(starts_with("Sepal")), ... )
Sorry if it is too trivial, but I don't know what I have to enter into google to find some useful pages.

Answer 1

We can use
library(dplyr)
iris1 <- iris %>%
mutate(across(starts_with("Sepal"),
~ (.^4-min(.^4)) / (max(.^4) - min(.^4)), .names = '{.col}2'))

Answer 2

my_function <- function(x) {
y = x^4-min(x^4)/max(x^4)/min(x^4)
return=y
}
iris %>%
mutate(across(starts_with("Sepal"), my_function))
Output:
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1 676.5198 150.05983 1.4 0.2 setosa
2 576.4798 80.99733 1.4 0.2 setosa
3 487.9678 104.85493 1.3 0.2 setosa
4 447.7453 92.34943 1.5 0.2 setosa
5 624.9997 167.95893 1.4 0.2 setosa
6 850.3053 231.34143 1.7 0.4 setosa
7 447.7453 133.63093 1.4 0.3 setosa
8 624.9997 133.63093 1.5 0.2 setosa
9 374.8093 70.72543 1.4 0.2 setosa
10 576.4798 92.34943 1.5 0.1 setosa
11 850.3053 187.41343 1.5 0.2 setosa
12 530.8413 133.63093 1.6 0.2 setosa
13 530.8413 80.99733 1.4 0.1 setosa
14 341.8798 80.99733 1.1 0.1 setosa
15 1131.6493 255.99733 1.2 0.2 setosa
.....