Dear R users: I'm trying to use "boot" function under the package boot to run some bootstrapping. Basically, I have a df as follows. (The data is simplified for illustrative purpose.) V1 V2 V3 1 2 3 4 5 7 3 5 2 Say that I want bootrap among (V1,V2,V3) for 1000 times and calculate the average of them, ie., v_bar still has lenght of 3. I think my question is really how to write bf function below. bf <- function(d,f) { gp1 <- 1:3 #indicate random draw from three series dmean <- apply(d[,gp1]*f[gp1],1,mean) } a <- boot(df,bf, R=1000, stype="f") Any help or suggestions? Many thanks. Yihsu