Hi, everyone. I have what I hope will be a simple coding question. It seems
this is a common job, but so far I've had trouble finding the answer in
searches.

I have two matrices (x and y) with a different number of observations in
each. I need to draw a random sample without replacement of observations
from x, and then, using a matching variable, draw a sample of equal size
from y. It is the matching variable that is hanging me up.

For example--

> # example matrices. lets assume seed always equals 1. (lets also assume I
have assigned variable names A and B to my columns..)
> set.seed(1)
> x<-cbind(1:10,sample(1:5,10,rep=T))
> x
      [A] [B]
 [1,]    1    2
 [2,]    2    2
 [3,]    3    3
 [4,]    4    5
 [5,]    5    2
 [6,]    6    5
 [7,]    7    5
 [8,]    8    4
 [9,]    9    4
[10,]   10    1

> y<-cbind(1:14,sample(1:5,14,rep=T))
> y
      [A] [B]
 [1,]    1    2
 [2,]    2    2
 [3,]    3    3
 [4,]    4    5
 [5,]    5    2
 [6,]    6    5
 [7,]    7    5
 [8,]    8    4
 [9,]    9    4
[10,]   10    1
[11,]   11    2
[12,]   12    1
[13,]   13    4
[14,]   14    2

> #draw random sample of n=4 without replacement from matrix x.
> x.samp<-x[sample(10,4,replace=F),]
> x.samp
     [A] [B]
[1,]    3    3
[2,]    4    5
[3,]    5    2
[4,]    7    5

Next, I would need to draw four observations from matrix y (without
replacement) so that the distribution of y$B is identical to x.samp$B.

I'd appreciate any help, and sorry to post such a basic question!

LB

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