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, 0, 0, 0, 0, 0, 0, 0), A2 = c(1, 
1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
), A3 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0), A4 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0), A5 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0), A6 = c(0, 0, 0, 0, 0, 
0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), A7 = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0
), A8 = c(0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 
1, 1, 1, 0, 0), A9 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0)), row.names = c(NA, -22L), class = c("tbl_df", 
"tbl", "data.frame"))

I have the following data frame. I need to extract and print the id's and comma separated column names where 1 is appearing. For example:

1 A1,A2
2 A1,A2
3 A1
4 A1
6 A2,A8
7 A6,A8

and so on...

How to proceed?

This is my attempt:

vec_ID <- c()
vec_JOB <- c()
job <- 0
for(i in 1 : length(ID)){
  for(j in 2:10){
    if(new[i,j]==1){
      vec_ID[i] <- ID[i] 
    }
  }
}
print(vec_ID)
vec_ID <- vec_ID[!is.na(vec_ID)]
#vec_ID <- as.data.frame(vec_ID)
print(vec_ID)

new_df <- new[ID[vec_ID],]
View(new_df)

for (i in 1:nrow(vec_ID)) {

}

Answer 1

You can do:

apply(df[-1], 1, function(x) toString(names(df[-1])[as.logical(x)]))

 [1] "A1, A2" "A1, A2" "A1"     "A1"     ""       "A2, A8" "A6, A8" "A1, A8" "A6, A8" "A8"     "A1, A8" "A6"    
[13] "A5, A8" ""       "A8"     "A8"     "A8"     "A8"     "A8"     "A8"     "A7"     ""