<br />
x = c(2,2,2,2,3,3,3,2,1,2,3,2,2,2,1,1,3,2,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1)<br />
lapply(1:length(unique(x)),function(i) which(x == i))<br />
[[1]]<br />
[1] 9 15 16 19 21 23 24 25 26 27 28 29 30 31 32 33 34</p>
<p>[[2]]<br />
[1] 1 2 3 4 8 10 12 13 14 18 20 22</p>
<p>[[3]]<br />
[1] 5 6 7 11 17<br />
</p>
