For_Auriel.R

# minimal dataset
dat <- data.frame(a = c(1, 5, 2), 
                  b = c(5, 2, 9), 
                  c = c(4, 3, 1))


rowMeans(dat)
# [1] 3.333333 3.333333 4.000000

do.call(rbind, lapply(seq_len(nrow(dat)),  function (k) {mean(as.numeric(dat[k, ]))}))
#          [,1]
# [1,] 3.333333
# [2,] 3.333333
# [3,] 4.000000

# to use rowMeans but get an output that looks just like the latter:
matrix(rowMeans(dat))
#          [,1]
# [1,] 3.333333
# [2,] 3.333333
# [3,] 4.000000

# still using *apply, but less typing:
matrix(apply(dat, 1, function (k) {mean(k)}))
#          [,1]
# [1,] 3.333333
# [2,] 3.333333
# [3,] 4.000000