R creating sample from ffdf object

Question

I have an ffdf object that has ~ 100 million rows of which I'd like to create a sample with ~ 5 million rows.

I used the following code but am not having any luck:

    > library(ffbase)
    > library(ff)
    > rowSamp1 <- c(1,3,5,7,9,11)
    > ff1 <- ff(runif(20))
    > ff2 <- ff(runif(20))
    > ff3 <- ff(runif(20))
    > ffdf1 <- ffdf(ff1, ff2, ff3)
    > dim(ffdf1)
    [1] 20  3
    > ffdf2 <- ffdf(ffdf1[rownames(ffdf1) %in% rowSamp1,])
    Error in as.hi.integer(x, maxindex = maxindex, dim = dim, vw = vw, pack = pack) : 
      NAs in as.hi.integer

Any suggestions?

Answer 1

ffdf1 [bigsample（x = 100000000，size = 5000000，replace = FALSE），]