Converting multiple boolean columns to single factor column

Question

my data frame look like this:

      A S1 S2 S3 S4
1   ex1  1  0  0  0
2   ex2  0  1  0  0
3   ex3  0  0  1  0
4   ex4  1  0  0  0
5   ex5  0  0  0  1
6   ex6         


        

Answer 1

Could also do (if dat is your data set)

library(reshape2)
dat <- melt(dat, id = "A")
dat[dat$value > 0, 1:2]