Concatenating and indexing highest values by grouped columns

I have the following dataset:

A1	A2	A3	A4	A5	A6	A7
-1.2650612	-0.6868529	-0.4456620	1.2240818	0.3598138	0.4007715	0.1106827

colnames<-c(paste0(1:7,"A"))
set.seed(123)
values<-c(rnorm(7))

I want to be able to create a code that will find the highest value (row-wise)found within the first 3 columns (A1,A2,A3) and write the corresponding column name, repeat the same for the following 2 columns and the same for the remaining 2 columns (A6,A7), if all values are the same (maybe it can happen then just write the name of the first columns within the group)

My desired output will be:

A1,A2,A3	A4,A5	A6,7
A3	A4	A5

What can I try next?

Solution

Here is one option

library(dplyr)
library(tibble)
library(tidyr)
pivot_longer(df1, everything()) %>%
  group_by(group = rep(1:3, c(3, 2, 2))) %>% 
  summarise(name1 = name[which.max(value)],
   name2 = toString(name)) %>% 
 select(name2, name1) %>% 
 deframe %>% 
 as_tibble_row

-output

# A tibble: 1 × 3
  `A1, A2, A3` `A4, A5` `A6, A7`
  <chr>        <chr>    <chr>   
1 A3           A4       A6

data

df1 <- structure(list(A1 = -1.2650612, A2 = -0.6868529, A3 = -0.445662, 
    A4 = 1.2240818, A5 = 0.3598138, A6 = 0.4007715, A7 = 0.1106827), 
class = "data.frame", row.names = c(NA, 
-1L))