Calculating the mean of a data table column in R (American Community Survey) and timing the result.

timer.R

doLoop <- function(method, iterations = 1000) {
    for (i in 1:iterations) {
        method();
    }
}

# Load csv file.
DT <- fread('https://d396qusza40orc.cloudfront.net/getdata%2Fdata%2Fss06pid.csv')

# Time option 2.
print(system.time(doLoop(function() tapply(DT$pwgtp15,DT$SEX,mean))))
# Time option 3.
print(system.time(doLoop(function() DT[,mean(pwgtp15),by=SEX])))
# Time option 6.
print(system.time(doLoop(function() sapply(split(DT$pwgtp15,DT$SEX),mean))))