Hi,
  I am not sure how you describe combine. 

Try this:
df1<-subset(df, !is.na(var1) &!is.na(var2))

df1$new<-paste0(df1$var1,df1$var2)
> head(df1)
#  var1 var2 new
#1    b    a  ba
#2    c    b  cb
#3    b    b  bb
#5    a    a  aa
#6    b    b  bb
#7    a    b  ab
A.K.



----- Original Message -----
From: Simon Kiss <sjk...@gmail.com>
To: r-help@r-project.org
Cc: 
Sent: Tuesday, September 11, 2012 10:57 AM
Subject: [R] Combine two variables

Hi:
I have two variables in a data frame that are the results of a wording 
experiment in a survey. I'd like to create a third variable that combines the 
two variables.  Recode doesn't seem to work, because it just recodes the first 
variable into the third, then recodes the second variable into the third, 
overwriting the first recode. I can do this with a rather elaborate indexing 
process, subsetting the first column and then copying the data into the second 
etc. But I'm looking for a cleaner way to do this. The data frame looks like 
this.


df<-data.frame(var1=sample(c('a','b','c',NA),replace=TRUE, size=100), 
var2=sample(c('a','b','c',NA),replace=TRUE,size=100))

df<-subset(df, !is.na(var1) |!is.na(var2))

As you can see, if one variable has an NA, then the other variable has a valid 
value, so how do I just combine the two variables into one?
Thank you for your assistance.
Simon Kiss

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