[R] Combine two variables

[PIKAL Petr]

Hi

I am not sure I understand correctly. In the sample dataframe you posted, the values in columns are different so based on what you did write I aasume that

apply(df,1, paste, collapse="")

gives you third variable combined from those 2 variables.

If you want to select non NA value from any variable, which one will you select when there is no NA in some row?

Regards
Petr 


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Simon Kiss
> Sent: Tuesday, September 11, 2012 4:57 PM
> To: r-help at r-project.org
> 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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