bradleyd wrote
Thanks for your help Pete. I can almost get it to work with;
by(day,year,quantile)
but this only gives me 0% 25% 50% 75% 100%, not the ones I'm looking for, 10% and 90%. I have tried;
by(day,year,quantile(c(0.1, 0.9))) but this is rejected by
Error in FUN(X[[1L]], ...) : could not find function "FUN"
Need to add the quantiles of interest ..... # Dummy Data d <- data.frame(year=c(rep(2010,10),rep(2011,10),rep(2012,10)), quantity = c(1:30)) # Quantiles by Year by(d$quantity,d$year,quantile,c(0.1,0.9)) HTH Pete -- View this message in context: http://r.789695.n4.nabble.com/Quantiles-of-a-subset-of-data-tp4659063p4659072.html Sent from the R help mailing list archive at Nabble.com.