Question

Given a set of real numbers stored in a data frame df under a column A, and an element r in this set, how would you solve the following ‘equation’ for q:

r = quantile(df$A, q)

Thanks for any help.

Answer 1

In ?quantile we can read

See Also

ecdf for empirical distributions of which quantile is an inverse

Thus:

x <- rnorm(100)

r <- quantile(x, 0.05)
#       5% 
#-1.469996 

Fn <- ecdf(x)
Fn(r)
#[1] 0.05