CODEWITHSUNDEEP
r
aliocee
aliocee

Reputation: 730

How to resample vector values in R?

I have two vectors:

x <- c(1, 2, 3, 4)
y <- c(5, 6, 7, 8, 9, 10)

now i want to resample n times to such that the numbers of the two vectors can shuffle randomly and maintain their dimension. Eg.

at n = 1

x <- c(2, 4, 7, 1)
y <- c(3, 9, 8, 6, 5, 10)

at n = 2

x <- c(5, 6, 10, 3)
y <- c(1, 9, 8, 4, 2, 7)

how can i accomplish this in R?

Upvotes: 1

Views: 1224

Answers (1)

MrFlick
MrFlick

Reputation: 206566

You could define your own helper function like

resample <- function(x,y) {
    xx <- sample(c(x,y))
    list(x=xx[1:length(x)], y=xx[-(1:length(x))])
}

and then use it with

# set.seed(15)
r1 <- resample(x,y)
r1$x
# [1] 7 2 8 5
r1$y
# [1]  3 10  4  1  9  6
r2 <- resample(x,y)
r2$x
# [1] 2 6 5 8
r2$y
# [1]  9  7 10  3  1  4

But it seems like you might be permuting case/control labels or something? In that case, you might have a vector of group assignments

group <- rep(c("x","y"), c(length(x),length(y)))

and then you could just sample() that each time to mix up groups

# set.seed(15)
(g1<-sample(group))
# [1] "y" "x" "y" "y" "x" "y" "x" "x" "y" "y"
(g2<-sample(group))
# [1] "x" "y" "y" "y" "y" "y" "y" "x" "x" "x"

and you could extract indexes with

which(g1=="x")
# [1] 2 5 7 8
which(g1=="y")
# [1]  1  3  4  6  9 10

if you really needed to.

Upvotes: 3

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