Sliding window in R

Question

I have a dataframe DF, with two columns A and B shown below:

A                    B                  
1                    0             
3                           


        

Answer 1

The R library TTR has a number of functions for calculating averages over sliding windows

SMA = simple moving average

data$sma <- SMA(data$B, 3)

More documentation is here http://cran.r-project.org/web/packages/TTR/TTR.pdf