Skip to content

renaming factor-labels / add factors etc.

3 messages · Jörg Groß, Peter Alspach, David Winsemius

Jörg Groß
# 
Hi,

how can I change a defined factor-variable?
Like adding levels, renaming existing levels or merge several levels  
of a factor to one level?



For example; following factor-variable is given:

  x <- factor(c("xyz1", "abc1", "xyz2", "abc2"))


How can I add the level fgh?
And how can I merge "xyz1" and "xyz2" to one level?
And how can I change the name?




Thanks for any help!
Peter Alspach
# 
J?rg

To add a level you could:

x <- factor(c("xyz1", "abc1", "xyz2", "abc2"))
x1 <- factor(x, levels=c(levels(x), 'fgh'))
summary(x)
abc1 abc2 xyz1 xyz2 
   1    1    1    1 
summary(x1)
abc1 abc2 xyz1 xyz2  fgh 
   1    1    1    1    0 

For the others, I tend to convert to a character, make the changes and convert back to a factor - but there is probably a better way.

HTH ....

Peter Alspach.
The contents of this e-mail are confidential and may be subject to legal privilege.
 If you are not the intended recipient you must not use, disseminate, distribute or
 reproduce all or any part of this e-mail or attachments.  If you have received this
 e-mail in error, please notify the sender and delete all material pertaining to this
 e-mail.  Any opinion or views expressed in this e-mail are those of the individual
 sender and may not represent those of The New Zealand Institute for Plant and
 Food Research Limited.
David Winsemius
#
On Dec 15, 2008, at 10:15 PM, Peter Alspach wrote:

            

      
      
      
    

        
Could also use:
levels(ff) <- c(levels(ff), "fgh")

            

      
      
      
    

        
> levels(ff)[3] <- "zippy"
 > levels(ff)
[1] "abc1"  "abc2"  "zippy" "xyz2"  "fgh"

Just a note that these are not the names:
 > names(ff)
NULL

Although you could add names.