I can create cumulative distribution by issuing following steps (as explained in this question):
> X = rnorm(100) # X is a sample of 100 normally distributed random variables
> P = ecdf(X) # P is a function giving the empirical CDF of X
> P(0.0) # This returns the empirical CDF at zero (should be close to 0.5)
[1] 0.52
> plot(P) # Draws a plot of the empirical CDF (see below)
Question: is it possible to reduce somehow the size of the X sample that way the original X sample and reduced X sample will both have same CDF shape (after plot)? Is this even mathematically possible? Thanks.