R error if statement 'argument is of length zero' [duplicate]

Question

I wrote three functions where two of the functions (namely function1 and function2) is used in the other function of populatedataset.

I was running the function populatedataset when i got an error of Error in if (num == 1) { : argument is of length zero

I believe that it is due to function2 due to the 'if (num == 1) {: ' portion.

function2 <- function(data, table, dict) {
  personindex <- substr(deparse(substitute(data)), start = 1, stop = 2)
  num <- table[person == as.character(personindex)]$newpersonality
  if (num == 1) {
    proptable <- data %>% inner_join(dict[score == 1]) %>% count(word)
    proportion <- sum(proptable$n)/nrow(data)
    return(proportion)
  }
  else {
    proptable <- data %>% inner_join(dict[score == 0]) %>% count(word)
    proportion <- sum(proptable$n/nrow(data))
    return(proportion)
  }
}


populatedataset <- function(data, table, dict) {
  list_a <- c(function1(data, dict), function2(data, table, dict))
  return (list_a)
}

I have been reading up on this error on other pages but I can't seem to find a solution related to this problem.

I would greatly appreciate any insight into this error!

Answer 1

A if condition has to be either TRUE or FALSE. This error implicates that num == 1 evaluates to a logical(0). This is probably caused by num being empty, i.e. numeric(0), because then you are comparing a numeric value of length 0 to 1 which gives a logical of length 0. You can wrap your condition num == 1 with the isTRUE function which would turn the logical(0) into a FALSE:

if (isTRUE(num == 1)){....

The function isTRUE checks if the argument is the logical value TRUE. Since num == 1 is logical(0) in this case, isTRUE will return FALSE and the if works as inteded.

On sidenote: num being numeric(0)is probably being caused by the fact that person == as.character(personindex) is not TRUE for any person so if you index your table no newpersonality value is returned. In this case you would run into the else portion of your if-else-construct if you use my solution.