distinct with incomparable

distinct2.r

library(dplyr, warn.conflicts = FALSE)

distinct2 <- function(df, predicate_incomparable, ...) {
  predicate_incomparable <- enquo(predicate_incomparable)
  
  # rows for which the predicate os true for at least one variable
  incomparables <- filter_all(df, any_vars(!!predicate_incomparable))
  
  # rows for which the predicate is false for all variables
  comparables <-  filter_all(df, all_vars(!(!!predicate_incomparable)))
  
  bind_rows(
    distinct(comparables, ...), 
    incomparables
  )
}

df <- tibble(
  a = c(1 , 1 , 2, NA, 2, 2, 2), 
  b = c(NA, NA, 1, 1 , 2, 2, 1), 
  c = rep(1, 7), 
)
df
#> # A tibble: 7 x 3
#>       a     b     c
#>   <dbl> <dbl> <dbl>
#> 1     1    NA     1
#> 2     1    NA     1
#> 3     2     1     1
#> 4    NA     1     1
#> 5     2     2     1
#> 6     2     2     1
#> 7     2     1     1

distinct2(df, is.na(.))
#> # A tibble: 5 x 3
#>       a     b     c
#>   <dbl> <dbl> <dbl>
#> 1     2     1     1
#> 2     2     2     1
#> 3     1    NA     1
#> 4     1    NA     1
#> 5    NA     1     1