Error Debug { : missing value where TRUE/FALSE needed

Question

I have been trying to run this code (below here) and I have getting this error:

for(i in 1:length(qid2))
{
  for(j in 1:length(qid))
  {
    if (qid2[i]==qid[i])
    {
        correct.option[i] = aid[j+cid[j]]
        print(correct.option[i])
    }
  }
}

Error in if (qid2[i] == qid[i]) { : missing value where TRUE/FALSE needed

What does the data look like? Also, it's a good idea to put opening brackets on the same line as the code that sets them up. — alistaire
Don't separate for( ... ) or if( ... ) and { with enter/return; keep them on the same line. if and for can work without the braces if there's more on the same setup line, so it makes it much easier to accidentally mess up your code. — alistaire
this question has been answered at: stackoverflow.com/questions/7355187/… — pengchy

Ben Bolker Ben Bolker · Accepted Answer · 2016-05-16T13:25:22

Probably because qid2 and qid are different lengths, so at some point i is larger than the shorter length, so that the comparison involves an element that doesn't exist. Perhaps you meant to compare qid2[i]==qid[j] ? The cat() statement below is an example of how you would debug this sort of thing.

qid2 <- 1:3
qid <- 1:2
for (i in 1:length(qid2)) {
   for(j in 1:length(qid)) {
       cat(i,j,qid[i],qid2[i],"\n")
       if (qid2[i]==qid[i]) {
       }
   }
}
## 1 1 1 1 
## 1 2 1 1 
## 2 1 2 2 
## 2 2 2 2 
## 3 1 NA 3 
## Error in if (qid2[i] == qid[i]) {
##     (from #4) : missing value where TRUE/FALSE needed

Error Debug { : missing value where TRUE/FALSE needed

1 Answers