Hi, is it possible to do this operation faster? I am going over 35k data entries and this takes quite some time. for(cnt in 2:length(sdata$date)) { if(sdata$value[cnt] < sdata$value[cnt - 1]) { sdata$ddtd[cnt] <- sdata$ddtd[cnt - 1] + sdata$value[cnt - 1] - sdata$value[cnt] } else sdata$ddtd[cnt] <- 0 } return(sdata) Thank you, Benjamin