[R] Reordering factor levels

[Peter Dalgaard BSA]

Ross Darnell <r.darnell at shrs.uq.edu.au> writes:

> I would like to define the order of the levels of a factor.
> 
> The relevel function would work but since I have 20 levels I would prefer
> to declare the order explicitly. Using a smaller example
> 
> levels(oldfactor)
> "b1" "b2" "r1" "r2"
> nufactor <- order(oldfactor,order=c("b1","r1","b2","r2")) # my fabricated function
> levels(nufactor)
> "b1" "r1" "b2" "r2"
> 
> Thanks in advance for any help.

e.g.:

> f <- factor(letters[1:3])
> g <- factor(f,levels=rev(levels(f))) # or levels(f)[c(3,1,2)], etc. 
> g
[1] a b c
Levels:  c b a 
> f
[1] a b c
Levels:  a b c 


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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