Dplyr Mutate_each for paired sets of columns

Question

Is there a way to achieve the following transformation using dplyr::mutate_each?

data.frame(x1 = 1:5, x2 = 6:10, y1 = rnorm(5), y2 = rnorm(5)) %>%
  mutat         


        

Answer 1

This does not use mutate_each, nor is it very pretty, nor do I think it will be very fast, but:

#create data set
p<-data.frame(x1 = 1:5, x2 = 6:10,
          y1 = rnorm(5), y2 = rnorm(5),
          z1 = 11:15, z2 = rnorm(5),
          w1 = rchisq(5,2), w2 = rgamma(5, .2)) 

#subset the columns by their column number and subtract them
p[,ncol(p)+seq(1,ncol(p)/2, by = 1)]<-
p[,seq(1,ncol(p),by = 2)]-p[,seq(2,ncol(p), by = 2)]

The data.frame p should be updated with half as many columns as it originally had, the new columns containing the difference of each pair (1-2, 3-4, 5-6) of originals.