[R] inequality with NA

[Uwe Ligges]

Mag. Ferri Leberl wrote:
> Dear everybody!
> take a<-c(5,3,NA,6).
> 
> if(a[1]!=NA){b<-7}
> if(a[3]!=5){b<-7}
> if(a[3]!=NA){b<-7}
> if(a[3]==NA){b<-7}
> 
> will alltogeather return
> 
> Fehler in if (a[1] != NA) { : Fehlender Wert, wo TRUE/FALSE nötig ist
> 
> (or simularly). Somehow this is logical. But how else should I get out,
> whether a certain vector-component has an existing value?

see ?is.na

Hence:
   if(!is.na(a[1])) b <- 7

Uwe Ligges


> Thank you in advance!
> Yours,
> Mag. Ferri Leberl
> 
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