Hi, i have a big performance problem in R. I wrote a function that iterates over an data.frame object. It simply adds a new col to a data.frame and accumulate sth. (simple operation). The data.frame has round about 850.000 rows. My PC is still working about 10h now and i have no idea about the runtime.

dayloop2 <- function(temp){
    for (i in 1:nrow(temp)){    
        temp[i,10] <- i
        if (i > 1) {             
            if ((temp[i,6] == temp[i-1,6]) & (temp[i,3] == temp[i-1,3])) { 
                temp[i,10] <- temp[i,9] + temp[i-1,10]                    
            } else {
                temp[i,10] <- temp[i,9]                                    
            }
        } else {
            temp[i,10] <- temp[i,9]
        }
    }
    names(temp)[names(temp) == "V10"] <- "Kumm."
    return(temp)
}

Any ideas how to speed up this operation ?