How to calculate returns from a vector of prices?

Question

I have to calculate the return of a vector that gives a historical price series of a stock. The vector is of a form:

a <- c(10.25, 11.26, 14, 13.56) 
         


        

Answer 1

Using your sample data, I think you mean the following:

a <- c(10.25, 11.26, 14, 13.56) 
> diff(a)/a[-length(a)]
[1]  0.09853659  0.24333925 -0.03142857

diff returns the vector of lagged differences and a[-length(a)] drops the last element of a.