Gather multiple columns into one key and two values

Question

I need to gather multiple columns into one key and two values. I encountered a lot of similar questions here, but i cannot reproduce the answers since they were very specific and not well explained imho. If there is one, which answers my question, i´m happy with a link.

Example df:

df <- data.frame(semester=rep(1:6),
                 Anna_try1=c(1,2,2,1,4,2),
                 Lena_try1=c(3,4,2,3,2,1),
                 Anna_try2=c(2,3,1,2,1,4),
                 Lena_try2=c(2,4,2,1,5,2))

which looks like this:

And i need something like this:

Answer 1

Try reshaping to long, separate the variables into desired new values and then reshape to wide. Here the code using tidyverse functions:

library(tidyverse)
#Code
df <- df %>% pivot_longer(-semester) %>%
  separate(name,c('name','try'),sep = '_') %>%
  mutate(try=paste0('grade_',try)) %>%
  pivot_wider(names_from = try,values_from=value) %>%
  arrange(name,semester)

Output:

# A tibble: 12 x 4
   semester name  grade_try1 grade_try2
      <int> <chr>      <dbl>      <dbl>
 1        1 Anna           1          2
 2        2 Anna           2          3
 3        3 Anna           2          1
 4        4 Anna           1          2
 5        5 Anna           4          1
 6        6 Anna           2          4
 7        1 Lena           3          2
 8        2 Lena           4          4
 9        3 Lena           2          2
10        4 Lena           3          1
11        5 Lena           2          5
12        6 Lena           1          2