R: Double Pivots Using DPLYR?

I am working with the R programming language.

I have a dataset that looks something like this:

x = c("GROUP", "A", "B", "C")
date_1 = c("CLASS 1", 20, 60, 82)
date_1_1 = c("CLASS 2", 37, 22, 8)
date_2 = c("CLASS 1", 15,100,76)
date_2_1 = c("CLASS 2", 84, 18,88)

my_data = data.frame(x,  date_1, date_1_1, date_2, date_2_1)

      x  date_1 date_1_1  date_2 date_2_1
1 GROUP CLASS 1  CLASS 2 CLASS 1  CLASS 2
2     A      20       37      15       84
3     B      60       22     100       18
4     C      82        8      76       88

I am trying to restructure the data so it looks like this:

note : in the real excel data, date_1 is the same date as date_1_1 and date_2 is the same as date_2_1 ... R wont accept the same names, so I called them differently

Currently, I am manually doing this in Excel using different "tranpose" functions - but I am wondering if there is a way to do this in R (possibly using the DPLYR library).

I have been trying to read different tutorial websites online (Pivoting), but so far nothing seems to match the problem I am trying to work on.

Can someone please show me how to do this?

Thanks!

Solution

Made assumptions about your data because of the duplicate column names. For example, if the Column header pattern is CLASS_ClassNum_Date

df<-data.frame(GROUP = c("A", "B", "C"),
               CLASS_1_1 = c(20, 60, 82),
               CLASS_2_1 = c(37, 22, 8),
               CLASS_1_2 = c(15,100,76),
               CLASS_2_2 = c(84, 18,88))
library(tidyr)
pivot_longer(df, -GROUP, 
             names_pattern = "(CLASS_.*)_(.*)", 
             names_to = c(".value", "Date"))

  GROUP Date  CLASS_1 CLASS_2
  <chr> <chr>   <dbl>   <dbl>
1 A     1          20      37
2 A     2          15      84
3 B     1          60      22
4 B     2         100      18
5 C     1          82       8
6 C     2          76      88

Edit: Substantially improved pivot_longer by using names_pattern= correctly