Using IRanges_1.4.0 here (checked elsewhere with 1.4.8): I would expect rep( Rle(x), times=Rle(x) ) == Rle( rep(x, x) ) but > x <- rep(1:4,c(1,2,1,2)) > Rle(rep(x,x)) 'integer' Rle of length 16 with 4 runs Lengths: 1 4 3 8 Values : 1 2 3 4 > rep(Rle(x),times=Rle(x)) 'integer' Rle of length 18 with 4 runs Lengths: 1 5 3 9 Values : 1 2 3 4 > rep(Rle(x),times=x) 'integer' Rle of length 18 with 4 runs Lengths: 1 5 3 9 Values : 1 2 3 4 > Is this the intended behavior? If so, why? Chuck Charles C. Berry (858) 534-2098 Dept of Family/Preventive Medicine E mailto:cberry at tajo.ucsd.edu UC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901