# [R] Odp: having problems with factor()

Petr PIKAL petr.pikal at precheza.cz
Fri Aug 10 14:02:21 CEST 2007

```Hi
r-help-bounces at stat.math.ethz.ch napsal dne 10.08.2007 13:41:53:

> Dear R Help,
> I have a set of data of heights of trees described by area that they are
in.
> The areas are numerical (0 to 7).
>
>     ht    area
> 1   320   3
> 2   410   4
> 3   230   2
> 4   360   3
> 5   126   1
> 6   280   2
> 7   260   2
> 8   280   2
> 9   280   2
> 10  260   2
> .......
> 180 450   4
> 181  90   1
> 182 120   1
> 183 440   4
> 184 210   2
> 185 330   3
> 186 210   2
> 187 100   1
> 188   0   0
>
> I want to convert the area column values to factors, to do an anova.
However, if I use:
>
> df\$areaf <- factor(df\$area,
labels=c("0","I","II","III","IV","V","VI","VII"))
>
> it gives the following message:
>

Hm, maybe some of the values are missing

> num<-sample(1:3, 10, replace=T)
> num
[1] 1 3 1 2 3 3 1 3 3 3
> factor(num, labels=c("O", "I", "II"))
[1] O  II O  I  II II O  II II II
Levels: O I II

> factor(num, labels=c("O", "I", "II", "III"))
Error in factor(num, labels = c("O", "I", "II", "III")) :
invalid labels; length 4 should be 1 or 3
>

try

table(df\$area)
to see what level you really have

Regards
Petr

> Error in factor(df\$area, labels = c("0", "I", "II", "III", "IV", "V",
"VI",  :
>         invalid labels; length 8 should be 1 or 7
>
> Can anyone help?
>
> Jabez
>
>
>       ___________________________________________________________
>
> now.
>
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>
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