[R] ordering of levels.

[Sundar Dorai-Raj]

Wolski wrote:

> Hi!
> Have the following factors with the following levels.
>  tmp$norm
>  [1] rank rank rank rank rank log  log  log  rank sqrt sqrt sqrt log  log  rank
> [16] rank rank sqrt sqrt sqrt sqrt log  log  log  log  sqrt none none none none
> [31] none none none none sqrt none
> Levels: log none rank sqrt
> 
> I would like to add an ordering to the levels.
> none<sqrt<log<rank
> 
> I tried with 
> tmp$norm <-factor(tmp$norm,labels = c("none","sqrt","log","rank"),ordered=T)
> 
>>tmp$norm
> 
>  [1] log  log  log  log  log  none none none log  rank rank rank none none log 
> [16] log  log  rank rank rank rank none none none none rank sqrt sqrt sqrt sqrt
> [31] sqrt sqrt sqrt sqrt rank sqrt
> Levels: none < sqrt < log < rank
> 
> But this is not what I would like to have because the command not only superimposes an ordering but also changes the factors!
> 
> Eryk
> 

Eryk,
   See ?factor or ?ordered which will help. I think what you want is:

lev <- c("none", "sqrt", "log", "rank")
tmp$norm <- ordered(tmp$norm, levels = lev)

or

tmp$norm <- factor(tmp$norm, levels = lev, ordered = TRUE)

Note the use of "levels" and not "labels".

--sundar