R writing binary data

Question

I have three big vectors with the same dimension. I need to write them in a binary file with a certain order: two integers followed by a double. Example:

a <- c(1,2,3,4) #integers
b <- c(5,6,7,8) #integers
d <- c(1.32421, 1.42342134123,21.4123412361,1.123412346) #doubles
# desired order:
# 1, 5, 1.32421, 2, 6, 1.42342134123, 3, 7, 21.4123412361, 4, 8, 1.12344112346

I would like doing it witout using a loop. Is it possible? This is my actual code for this example:

con_ <- "a"
file.create(con_)
con <- file(con_,"wb")
for(i in seq(1,length(a))){
  ve <- c(a[i],b[i])
  writeBin(ve,con, size = 4)
  writeBin(d[i],con, size = 8)
}

Answer 1

You can rbind the vectors to get the vectors in the desired order.

c(rbind(a, b, d))
#Similar to
#c(t(cbind(a, b, d)))

#[1]  1.00  5.00  1.32  2.00  6.00  1.42  3.00  7.00 21.41  4.00  8.00  1.12

Note that you can have data of only one class in a vector. So in this example, all of them turn into numeric.

Answer 2

We can do this with order and it should also work when the lengths are not the same

c(a, b, d)[order(c(seq_along(a), seq_along(b), seq_along(d)))]
#[1]  1.000000  5.000000  1.324210  2.000000  6.000000  1.423421  3.000000  7.000000 21.412341  4.000000  8.000000  1.123412