Insert NA after specified number of rows using R

December 29, 2021

I got a df such as this

structure(list(id = c(1, 1, 1, 2, 2, 2), hosp = c(156, 186, 891, 
221, 231, 246), out = c(185, 235, 1062, 230, NA, 250), insti = c(NA, 
NA, NA, NA, 245, NA), days = c(1063, 1063, 1063, 251, 251, 251
), status = c(1, 1, 1, 1, 1, 1)), class = "data.frame", row.names = c(NA, 
-6L))

and I would like to keep the values in the last row of column "days" and "status" for each id. I want the data to look like this

structure(list(id2 = c(1, 1, 1, 2, 2, 2), hosp2 = c(156, 186, 
891, 221, 231, 246), out2 = c(185, 235, 1062, 230, NA, 250), 
    insti2 = c(NA, NA, NA, NA, 245, NA), days2 = c(NA, NA, 1063, 
    NA, NA, 251), status2 = c(NA, NA, 1, NA, NA, 1)), class = "data.frame", row.names = c(NA, 
-6L))

>Solution :

A possible solution:

library(tidyverse)

df %>% 
  group_by(id) %>% 
  mutate(days = if_else(row_number() == n(), days, NA_real_),
         status =  if_else(row_number() == n(), status, NA_real_)) %>% ungroup

#> # A tibble: 6 × 6
#>      id  hosp   out insti  days status
#>   <dbl> <dbl> <dbl> <dbl> <dbl>  <dbl>
#> 1     1   156   185    NA    NA     NA
#> 2     1   186   235    NA    NA     NA
#> 3     1   891  1062    NA  1063      1
#> 4     2   221   230    NA    NA     NA
#> 5     2   231    NA   245    NA     NA
#> 6     2   246   250    NA   251      1