Recover the number of iteration in a loop

[laplanca]

I have this code :

library(tidyverse)

input_data = tribble(
  ~"id", ~"name", ~"surname", ~"date_test", ~"result_test",
  1 , "franck" , "wilson" , "01-2002" , "P",
  1 , "franck" , "wilson" , "07-2004" , "N",
  1 , "franck" , "wilson" , "04-2008" , "N",
  2 , "annie", "mark", "08-2001" , "N",
  2 , "annie", "mark", "03-2005" , "P"
)

output_data = input_data %>% 
  # add a counter for the tests performed
  group_by(id, name, surname) %>% 
  mutate(test_rep = 1:n()) %>%
  pivot_longer(cols = c(date_test, result_test),
               names_to = "variable",
               values_to = "readout") %>% 
  pivot_wider(id_cols = c(id, name, surname),
              names_from = c(variable, test_rep),
              names_sep = "_",
              values_from = readout)

output_data
# A tibble: 2 x 9
# Groups:   id, name, surname [2]
     id name   surname date_test_1 result_test_1 date_test_2 result_test_2 date_test_3 result_test_3
  <dbl> <chr>  <chr>   <chr>       <chr>         <chr>       <chr>         <chr>       <chr>        
1     1 franck wilson  01-2002     P             07-2004     N             04-2008     N            
2     2 annie  mark    08-2001     N             03-2005     P             NA          NA     

and I want to recover in a variable the number max of tests, like here 3. I tried unsuccessfully with something like this

maxTest<- n

Thank you for your help

[StatSteph]

There's a few ways to do this but here's one way:

library(tidyverse)

input_data = tribble(
  ~"id", ~"name", ~"surname", ~"date_test", ~"result_test",
  1 , "franck" , "wilson" , "01-2002" , "P",
  1 , "franck" , "wilson" , "07-2004" , "N",
  1 , "franck" , "wilson" , "04-2008" , "N",
  2 , "annie", "mark", "08-2001" , "N",
  2 , "annie", "mark", "03-2005" , "P"
)

intermediate_data = input_data %>% 
  # add a counter for the tests performed
  group_by(id, name, surname) %>% 
  mutate(test_rep = row_number()) 

maxTest <- pull(intermediate_data, test_rep) %>% max()

output_data <- intermediate_data %>%
  pivot_longer(cols = c(date_test, result_test),
               names_to = "variable",
               values_to = "readout") %>% 
  pivot_wider(id_cols = c(id, name, surname),
              names_from = c(variable, test_rep),
              names_sep = "_",
              values_from = readout)

maxTest
#> [1] 3
output_data
#> # A tibble: 2 x 9
#> # Groups:   id, name, surname [2]
#>      id name   surname date_test_1 result_test_1 date_test_2 result_test_2
#>   <dbl> <chr>  <chr>   <chr>       <chr>         <chr>       <chr>        
#> 1     1 franck wilson  01-2002     P             07-2004     N            
#> 2     2 annie  mark    08-2001     N             03-2005     P            
#> # ... with 2 more variables: date_test_3 <chr>, result_test_3 <chr>

^{Created on 2022-04-05 by the reprex package (v2.0.1)}