rollapply with “growing” window

Question

Guys, normally when you do something like:

tmp = zoo(rnorm(100), 1:100)
rollapply(tmp, 10, function(x) quantile(x, 0.05), align=\"right\")

Answer 1

Why not just pad the series with 9 NAs at the beginning? Definitely better than "ugly for loops":

tmp = zoo(c(rep(NA,9), rnorm(100)), 1:109)
zoo(rollapply(tmp, 10, function(x) quantile(x, 0.05, na.rm = TRUE), 
              align="right"), 1:100)