[R] Ifelse stability problems?

[Peter Ehlers]

On 2010-12-19 03:50, Luca Meyer wrote:
> I am just wondering why what I am showing below might occur.
>
> First I have an x data.frame:
>
>> str(x)
> 'data.frame':   281 obs. of  2 variables:
>   $ x1   : Factor w/ 5 levels "A (50-67%)","B (10-20%)",..: 1 2 5 1 2 5 1 2 5 1 ...
>   $ x2   : num  33.8 60.2 6 76.8 13.8 9.4 76.9 8 15.1 78.1 ...
>
> I need to check that for each level of factor x1 the values of x2 are (approximately) contained within a given range. In such a case I will print "ok" a third variable, otherwise I will write "err"
>
> ifelse (x$x1 == "A (50-67%)",
>      x$check<-ifelse(x$x2<68&x$x2>49,"ok","xxxx"),
>      x$check<-x$check
> )

[...snip...]

> Can anyone explain why this might occur?

You have a bit of a logic problem in your ifelse;
(look at your x$check after each of your ifelse()s);
try it this way:

  x$check <- NA
  x$check <- ifelse (x$x1 == "A (50-67%)",
     ifelse(x$x2<68&x$x2>49,"ok","xxxx"),
     x$check
  )

etc.

Peter Ehlers


>
> Thanks,
> Luca
>
>
> Luca Meyer
> www.lucameyer.com
> IBM SPSS Statistics release 19.0.0
> R version 2.12.1 (2010-12-16)
> Mac OS X 10.6.5 (10H574) - kernel Darwin 10.5.0
>
>
>