Alternate, interweave or interlace two vectors

r, vector

Solution

Your `rbind` method should work well. You could also use

rpois(lambda=c(3,4),n=1e6)

because R will automatically replicate the vector of lambda values to the required length. There's not much difference in speed:

library(rbenchmark)
benchmark(rpois(1e6,c(3,4)),
     c(rbind(rpois(5e5,3),rpois(5e5,4))))


#                                        test replications elapsed relative
# 2 c(rbind(rpois(5e+05, 3), rpois(5e+05, 4)))          100  23.390 1.112168
# 1                      rpois(1e+06, c(3, 4))          100  21.031 1.000000

and elegance is in the eye of the beholder ... of course, the `c(rbind(...))` method works in general for constructing alternating vectors, while the other solution is specific to `rpois` or other functions that replicate their arguments in that way.

Problem

I want to interlace two vectors of same mode and equal length. Say: ``` a <- rpois(lambda=3,n=5e5) b <- rpois(lambda=4,n=5e5) ``` I would like to interweave or interlace these two vectors, to create a vector that would be equivalently `c(a[1],b[1],a[2],b[2],...,a[length(a)],b[length(b)])` My first attempt was this: ``` sapply(X=rep.int(c(3,4),times=5e5),FUN=rpois,n=1) ``` but it requires `rpois` to be called far more times than needed. My best attempt so far has been to transform it into a matrix and reconvert back into a vector: ``` d <- c(rbind(rpois(lambda=3,n=5e5),rpois(lambda=4,n=5e5))) d <- c(rbind(a,b)) ``` Is there a better way to go about doing it? Or is there a function in base `R` that accomplishes the same thing?

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