[R] missing value where TRUE/FALSE needed

[Erik Iverson]

They may be the same length; that's not what the error message is 
complaining about:  it says there is a missing value (i.e., an NA) where 
a TRUE/FALSE value is needed, therefore the 'if' doesn't know what to 
do, since it is not TRUE or FALSE. So, try

summary(vector1)
summary(vector2)

sum(is.na(vector1))
sum(is.na(vector2))

to see if/where/why there are NAs in these vectors.

David Croll wrote:
> Hello dear R people,
> 
> 
> for my MSc thesis I need to program some functions, and some of them 
> simply do not work. In the following example, I made sure both vectors 
> have the same length (10), but R gives me the following error:
> 
> Error in if (vector1[i] == vector2[j]) { :
>  missing value where TRUE/FALSE needed
> 
> I googled for possible solutions, but I did not find a good explanation 
> for this...
> 
> 
> The code:
> 
> test <- function() {
>      vector1 <- sample(1:100,10)
>    vector2 <- sample(1:100,10)
>      for (i in vector1) {
>              for (j in vector2) {
>                      if (vector1[i] == vector2[j]) {
>                              show(list(i,j))
>                              }
>                          }
>              }
>      }  
> 
> Regards, David
> 
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