Hello:

I wonder if I could get a little help with random sampling in R.

I have a vector of length 7375.  I would like to draw 3 distinct random samples, each of length 100 without replacement.  I have tried the following:

d1 <- 1:7375

set.seed(7)
i <- sample(d1, 100, replace=F)
s1 <- sort(d1[i])
s1

d2 <- d1[-i]
set.seed(77)
j <- sample(d2, 100, replace=F)
s2 <- sort(d2[j])
s2

d3 <- d2[-j]
set.seed(777)
k <- sample(d3, 100, replace=F)
s3 <- sort(d3[k])
s3

D <- data.frame(a=s1,b=s2,c=s3)


However, s2 is only 97 elements long, and s3, only 96 long.

I would appreciate any suggestions on a better approach.
I'm also curious to know why my second and third samples are less than 100 elements in length.

Thanks for your time and consideration,

Cesar A. Hincapié, DC, MHSc

Research Fellow, Division of Health Care and Outcomes Research, Toronto Western Research Institute
PhD Candidate in Epidemiology, Dalla Lana School of Public Health, University of Toronto
e. cesar.hincapie@utoronto.ca





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