[R] Problems with NA's

[J. R. M. Hosking]

Thomas L Jones, PhD wrote:
> Difficulty handling NA's:
> Assume that I have a numeric vector y. For simplicity, assume that it has 10 
> elements. Assume that the third element has the value NA. I give it the 
> following:
> NA_test <- function (){
> y <- numeric (10)
> y [3] <- NA
> if (y [3] != NA){(print ("no")}
> print ("Leaving NA_test")
> return ()
> }# End of function
> 
> -------------------------------------------------------------
> Unfortunately, things become confused involving the NA element.
> Here is the output, starting with the loading process:
> 
> ----------------------------------------------------------
>> NA_test <- function (){
> + y <- numeric (10)
> + y [3] <- NA
> + if (y [3] != NA){(print ("no")}
> Error: syntax error in:
> "y [3] <- NA
> if (y [3] != NA){(print ("no")}"
>> print ("Leaving NA_test")
> [1] "Leaving NA_test"
>> return ()
> Error: no function to return from, jumping to top level
>> }# End of function
> Error: syntax error in "}"
> ---------------------------------------------------------------------
> I have enclosed the print operation in braces to avoid possible problems 
> with it.
> 
> Your advice?
> 
> Tom Jones

What Messrs. Schwartz and Olshansky told you is valid, but will not cure 
syntax errors.  My advice is to check the matching of parentheses in the 
line

 > if (y [3] != NA){(print ("no")}



J. R. M. Hosking