Reclassify string values

Hi All,

Is there a simple way to convert a string such as c("A", "B" ,"C", "D") 
to a string of c("Group1", "Group1", "Group2", "Group2"). Naturally I 
could use the factor function as below but I don't like seeing that 
warning message (and I don't want to turn off warning messages). Perhaps 
a function called "reclassify" or "recategorize"?

Zev

x<-LETTERS[1:4]
x2<-as.character(factor(x, levels=LETTERS[1:4], labels=rep(c("Group1", 
"Group2"), each=2)))

Warning message:
In `levels<-`(`*tmp*`, value = c("Group1", "Group1", "Group2", "Group2" :
   duplicated levels will not be allowed in factors anymore

Zev Ross
ZevRoss Spatial Analysis
120 N Aurora, Suite 3A
Ithaca, NY 14850
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zev at zevross.com