Loop through columns multiple times, write each result to data.frame - r

Question

I am trying to loop through various columns in a data frame then loop through the dataframe again after subsetting it by date (with multiple start and end dates). I would like the results to be appended to a new dataframe each time through, but the results are being overwritten each time through the loop. The final dataframe (finaldf) only has the results of the last pass through the loop. What is the best way to get the finaldf to contain all of the results from both loops (i.e. outlooks and columns)?
tempdf <- read_csv(path)
datalist <- list()
outlooks <- list("whole", "short", ...)
for(o in outlooks){
if(o == "whole" | o == "short"){ startDate = as.Date(tempdf$Date[[1]])
} else if( o == "mid"){ startDate = as.Date((tempdf$Date[[1]] + 30))
}
if(o == "whole" | o == "long"){ endDate = as.Date(tempdf$Date[[len]])
} else if( o == "mid"){ endDate = as.Date((tempdf$Date[[1]] + 60))
}
tempdf[tempdf$Date >= startDate & tempdf$Date <= endDate,]
colList <- names(tempdf)
target <- tempdf[[2]]
f <- substr(colList[[2]],1,3)
for(j in colList[-c(1,2)]){
fitted <- as.numeric(tempdf[[j]])
datalist[[j]] <- data.frame(
RMSE = RMSE(fitted, target),
R2 = R2(fitted, target),
NSE = NSE(fitted, target),
pbias = pbias(fitted, target)
)
}
}
finaldf <- do.call(rbind, datalist)