Skip to content

can't find the error in if function... maybe i'm blind?

3 messages · Janosch, Milan Bouchet-Valat, jim holtman

Janosch
# 
Hi everybody,

the following alway gives me the error
 "Fehler in if (File$X.Frame.Number[a] + 1 == File$X.Frame.Number[a + 1])
(File$FishNr[a] <- File$FishNr[a -  :   Fehlender Wert, wo TRUE/FALSE n?tig
ist". Maybe its stupid, but i'm not getting why... Maybe someone can help
me.  Thanks a lot!

for (i in unique(BigFile$TrackAll))
      { File <-  subset(BigFile,BigFile$TrackAll == i)
         File$FishNr [1]  <- 1
          for ( a in File$X.Frame.Number)
               {if(File$X.Frame.Number[a]+1==  File$X.Frame.Number[a+1])
                (File$FishNr [a] <- File$FishNr[a-1])
                else(if (File$X.Frame.Number[a]+1 !=
File$X.Frame.Number[a+1])
                      (File$FishNr [a] <- File$FishNr[a-1]+1   ))
           }
       }



--
View this message in context: http://r.789695.n4.nabble.com/can-t-find-the-error-in-if-function-maybe-i-m-blind-tp4646839.html
Sent from the R help mailing list archive at Nabble.com.
Milan Bouchet-Valat
# 
Le samedi 20 octobre 2012 ? 03:27 -0700, Janosch a ?crit :
You could have told us what this error means in English, but my guess is
that File$X.Frame.Number[a] or File$X.Frame.Number[a + 1] is NA, which
means that the whole expression evaluates to NA, which is not corrrect
for if(). If you want NAs to be considered as FALSE, than put the
expression inside a isTRUE() call. If NAs are not expected there in your
code, there's a problem elsewhere.

Since the loop stops when the error is raised, "a" still contains the
value that produced it and you can easily check where the problem comes
from that way.


My two cents
jim holtman
# 
Learn how to debug your programs.  Start with

options(error = recover)

this will give you control at the point of the error so you can examine values.  Most likely one of the variables in the 'if' expression is an NA.

Sent from my iPad
On Oct 20, 2012, at 6:27, Janosch <Janosch1985 at web.de> wrote: