Rollapply for row in R with exp function

Question

I have the data frame df(A) with 14 col and 1356 row. I have this function, for to apply a sum for every 12 row, like a moving average:

rollapply(A,width=12, FUN= sum,by.column=T) 

But inside every 12 row i need to apply a multiplication for exp(n/12) , where n are numbers from 0 to 11. In synthesis the results could be:

rollapply(A,FUN=1°row *exp(0/12)+2°row*exp(2/12)....+12°row*exp(11/12),by.column=T) 

Logically every 12 row the operation is repeated. Is possible apply this with function rollapply or i need to write a loop for ?

Answer 1

You just need to update your function:

n = 12
rollapply(A, width=n, FUN=function(x) sum(x*exp((seq(n)-1)/n)))