Hello everyone,

Can somebody give a hint on how to go about speeding the following loop:

system.time(
for(i in 1:nrow(dat)){
if(dat$ycon[i]==0 || dat$ytrt[i]==0)
    dat$ycon[i]<-dat$ycon[i]+0.5
    dat$ytrt[i]<-dat$ytrt[i]+0.5
    dat$cony[i]<-dat$cony[i]+0.5
    dat$trty[i]<-dat$trty[i]+0.5
}
    )


-- 
-Tony

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