Calculating Running Percentile in R

Question

I'm trying to calculate the percentiles from 1:i in a column. For example, for the nth data point, calculate the percentile only using the first n values.

I have tried using quantile , but can't seem to figure out how to generalize it.

mydata <- c(1, 25, 43, 2, 5, 17, 40, 15, 12, 8)

Answer 1

perc.fn <- function(vec, n){
(rank(vec[1:n], na.last=TRUE) - 1)/(length(vec[1:n])-1)}