[R] knowing the code-number of factors in a vector

Rainer Schuermann Rainer.Schuermann at gmx.net
Sat Dec 4 02:04:31 CET 2010

It seems to be dependent upon the the character ("assigned alphabetically") which I found out by manually changing the order of appearance of the characters in rfactor; the colour would stick to the character "a", whether this appears first in rfactor or not.

I as able to control the colours being used by
> boxplot(x~rfactor, col=c("2", "6", "3","5","4"))


I'm new to R and very early on the learning curve - just trying my best...

On Saturday 04 December 2010 01:22:56 Eduardo Klein wrote:
> Hi,
> I would like to know how R assigns the numeric code to a set of factors 
> in a vector. For example, I have a vector of 5 different factors in a 
> random order, and I want a color-coded plot by factors:
> rfactor=as.factor(sample(letters[1:5], 50, replace=T))
> rfactor
>   [1] c c c d b a b d d a a e e b b e c e e a a b b b a b a e a a b d b 
> b c a b b
> [39] d c a e c d e d a a a a
> Levels: a b c d e
> x=rnorm(50)
> boxplot(x~rfactor, col=1:5)
> So, colors 1 to 5 are assigned to factors alphabetically (a-1, b-2, ..., 
> e-5), or by order of appearance (c-1, d-2, b-3, a-4, e-5)? It is 
> possible to control that?
> Saludos, EKS

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