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Problem :

I have received below error message:

Error in if (condition) { : missing value where TRUE/FALSE needed


Error in while (condition) { : missing value where TRUE/FALSE needed

What does it actually mean, and how can I fix this error?

6 5 3
7,540 points

2 Answers

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Solution :


Here the evaluation of the condition must have resulted in an NA. Any if condition must return either a TRUE or FALSE result as shown below :

if (NA) {}
## Error in if (NA) { : missing value where TRUE/FALSE needed

This can happen with anybody accidentally as the results of the calculations as shown below :

if(TRUE && sqrt(-1)) {}
## Error in if (TRUE && sqrt(-1)) { : missing value where TRUE/FALSE needed


Also to test whether any object is missing please use is.na(x) rather than the x == NA.

I also ran into this error in the recent past when I was trying to check on the null or empty string as shown below :

if (x == NULL || x == '') {

Then I did the lot of research on it and at the end of it I realized my mistake and I changed it as below:

if (is.null(x) || x == '') {


Hope it solves your issue.

9 7 4
38,600 points
0 votes


Consider  having this same issue when trying to view a data set we imported. we could also view individual elements but not the whole data set. we solved it by converting it to a data frame using


R has a wierd (and super annoying) way of handling NAs. if your output is empty then nchar(output) will return integer(0). You can get around this by adding another if statement with if(length(nchar(output)) > 0){...}

I did tests with the function with far less observations, but also generating 0 obs in "Unique in SetY" And I had no problem viewing those lists

May be you forgot to update the "Save workspace to .Rdata upon exit" to Never. After that change, you re-started R-studio and the error message did not re-appear. 

Updating R and sp to the released versions will resolve this.

It was caused by a change in R's behavior on what nchar(NA) returns: see the help file of ?nchar, argument keepNA.

we think the issue might be your use of things like all$age7. we suspect that 'all' is the name of a data frame and you intend the mxMatrix named 'Age' to be a matrix full of definition variables.

Following code:

# definition variable
    labels=paste("data.age", c(7, 8, 1:6), sep=""),


10 6 4
31,120 points

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