For Loop in R (Looking for an alternative) - r

Question

The following code runs a loops but the problem is the speed; it takes several hours to finish and I am looking for an alternative so that I don´t have to wait so long.
Basically what the code does the follolling calculations:
1.-It calculates the mean of the values of the 60 days.
2.-It gets the standard deviation of the values of the 60 days.
3.-It gets the Max of the values of the 60 days.
4.-It gets the Min of the values of the 60 days.
5.-Then with the previous calculations the code "smooths" the peaks up and down.
6.-Then the code simply get the means from 60, 30, 15 and 7 Days.
So the purpose of these code is to remove the peaks of the data using the method already mentioned.
Here is the code:
options(stringsAsFactors=F)
DAT <- data.frame(ITEM = "x", CLIENT = as.numeric(1:100000), matrix(sample(1:1000, 60, replace=T), ncol=60, nrow=100000, dimnames=list(NULL,paste0('DAY_',1:60))))
DATT <- DAT
nRow <- nrow(DAT)
TMP <- NULL
for(iROW in 1:nRow){#iROW <- 1
print(c(iROW,nRow))
Demand <- NULL
for(iCOL in 3:ncol(DAT)){#iCOL <- 1
Demand <- c(Demand,DAT[iROW,iCOL])
}
ww <- which(!is.na(Demand))
if(length(ww) > 0){
Average <- round(mean(Demand[ww]),digits=4)
DesvEst <- round(sd(Demand,na.rm=T),digits=4)
Max <- round(Average + (1 * DesvEst),digits=4)
Min <- round(max(Average - (1 * DesvEst), 0),digits=4)
Demand <- round(ifelse(is.na(Demand), Demand, ifelse(Demand > Max, Max, ifelse(Demand < Min, Min, Demand))))
Prom60 <- round(mean(Demand[ww]),digits=4)
Prom30 <- round(mean(Demand[intersect(ww,(length(Demand) - 29):length(Demand))]),digits=4)
Prom15 <- round(mean(Demand[intersect(ww,(length(Demand) - 14):length(Demand))]),digits=4)
Prom07 <- round(mean(Demand[intersect(ww,(length(Demand) - 6):length(Demand))]),digits=4)
}else{
Average <- DesvEst <- Max <- Min <- Prom60 <- Prom30 <- Prom15 <- Prom07 <- NA
}
DAT[iROW,3:ncol(DAT)] <- Demand
TMP <- rbind(TMP, cbind(DAT[iROW,], Average, DesvEst, Max, Min, Prom60, Prom30, Prom15, Prom07))
}
DAT <- TMP

Answer 1

If one runs your code (with smaller number of rows) through a profiler, one sees that the main issue is the rbind in the end, followed by the c mentioned by #Riverarodrigoa:
We can focus on these two by creating numeric matrices of suitable size and working with those. Only in the end the final data.frame is created:
options(stringsAsFactors=F)
N <- 1000
set.seed(42)
DAT <- data.frame(ITEM = "x",
CLIENT = as.numeric(1:N),
matrix(sample(1:1000, 60, replace=T), ncol=60, nrow=N, dimnames=list(NULL,paste0('DAY_',1:60))))
nRow <- nrow(DAT)
TMP <- matrix(0, ncol = 8, nrow = N,
dimnames = list(NULL, c("Average", "DesvEst", "Max", "Min", "Prom60", "Prom30", "Prom15", "Prom07")))
DemandMat <- as.matrix(DAT[,3:ncol(DAT)])
for(iROW in 1:nRow){
Demand <- DemandMat[iROW, ]
ww <- which(!is.na(Demand))
if(length(ww) > 0){
Average <- round(mean(Demand[ww]),digits=4)
DesvEst <- round(sd(Demand,na.rm=T),digits=4)
Max <- round(Average + (1 * DesvEst),digits=4)
Min <- round(max(Average - (1 * DesvEst), 0),digits=4)
Demand <- round(ifelse(is.na(Demand), Demand, ifelse(Demand > Max, Max, ifelse(Demand < Min, Min, Demand))))
Prom60 <- round(mean(Demand[ww]),digits=4)
Prom30 <- round(mean(Demand[intersect(ww,(length(Demand) - 29):length(Demand))]),digits=4)
Prom15 <- round(mean(Demand[intersect(ww,(length(Demand) - 14):length(Demand))]),digits=4)
Prom07 <- round(mean(Demand[intersect(ww,(length(Demand) - 6):length(Demand))]),digits=4)
}else{
Average <- DesvEst <- Max <- Min <- Prom60 <- Prom30 <- Prom15 <- Prom07 <- NA
}
DemandMat[iROW, ] <- Demand
TMP[iROW, ] <- c(Average, DesvEst, Max, Min, Prom60, Prom30, Prom15, Prom07)
}
DAT <- cbind(DAT[,1:2], DemandMat, TMP)
For 1000 rows this takes about 0.2 s instead of over 4 s. For 10.000 rows I get 2 s instead of 120 s.
Obviously, this is not really pretty code. One could do this much nicer using tidyverse or data.table. I just find it worth noting that for loops are not necessarily slow in R. But dynamically growing data structures is.