[R] how to combine multiple indicator variables in a single factor

[ehud cohen]

you can try:

df$f<-names(df)[apply(df,1,function(x) which(x==1))]

Ehud

On Fri, Dec 18, 2009 at 10:48 PM, Daniel Nordlund
<djnordlund at verizon.net> wrote:
> Say I have a dataframe like this:
>
> df <- data.frame(cbind(c(1,0,0,1),c(0,1,0,0),c(0,0,1,0)))
>
> names(df) <- c('a','b','c')
>
> I would like to create a factor in a new column, where the factor values are taken from the column names, like this:
>
>> df2
>  a b c f
> 1 1 0 0 a
> 2 0 1 0 b
> 3 0 0 1 c
> 4 1 0 0 a
>
> How would I do this?  Thanks,
>
> Dan
>
> Daniel Nordlund
> Bothell, WA USA
>
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