Extracting column names with condition from a data frame

Question

dput(new)
structure(list(ID = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 
13, 14, 15, 16, 17, 18, 19, 20, 21, 22), A1 = c(1, 1, 1, 1, 0, 
0, 0, 1, 0, 0, 1, 0, 0, 0, 0,         


        

Answer 1

Here is a purrr solution:

is_one <- function(x) all(x == 1)

df %>% 
   nest(-ID) %>% 
   mutate(eval = purrr::map_chr(data, ~ paste0(.x %>% 
                                             dplyr::select_if(is_one) %>%  
                                             names(.), collapse = ", ")))

# A tibble: 22 x 3
      ID           data eval  
    >  
 1     1        [1 x 9] A1, A2
 2     2        [1 x 9] A1, A2
 3     3        [1 x 9] A1    
 4     4        [1 x 9] A1    
 5     5        [1 x 9] ""    
 6     6        [1 x 9] A2, A8
 7     7        [1 x 9] A6, A8
 8     8        [1 x 9] A1, A8
 9     9        [1 x 9] A6, A8
10    10        [1 x 9] A8