Might be a trivial question but how to identify the odd and even indices of a vector? x = c(1,z,w,2,6,7) el of odd indices= 1,w,6 el of even indices= z,2,7 given the def of odd and even in https://stat.ethz.ch/pipermail/r-help/2010-July/244299.html should a loop be used? for (i in 1: length(x)) if (is.odd(i)) print (i) Carol [[alternative HTML version deleted]]