r - Referring values in a matrix (extended) -

i have r code friend takes numeric vector, , each number checks if number same upside down.

numbers = (0:9) upside_down_numbers = c(0,1,na,na,na,na,9,na,8,6) ref_table = rbind(numbers,upside_down_numbers) invertible = function(n){    as.numeric(paste0(     upside_down_numbers[       1+rev(as.numeric(strsplit(as.character(n),"")[[1]]))       ],collapse=""))} 

i want return true if number entered same number returned example:

invertible(69) [1] 69 

and false if number entered different number returned or returns na example:

invertible(99) [66] 

i want code able work on multiple numbers example:

invertible(c(1, 96, 99, 123, 1691)) [1] true true false false true 

really stuck @ point, appreciate advice. thank you

this unusual task... work you.

invertible_test <- function(n) {   inverted <- suppresswarnings(invertible(n))   if (is.na(inverted)) {     return(false)   }   return(n == inverted) }  invertible_test_vector <- function(v) {   vapply(v, invertible_test, c(t)) } 

here passes test:

invertible_test_vector(c(1, 96, 99, 123, 1691)) [1]  true  true false false  true