[R] Looking for help in calculating percentiles

[Jason Turner]

> Hi All:
>
> I am working with a dataset on Arsenic toxicity, and I am trying to
> calculate the 20th, 40th, 60th, 80th, and highest percentiles for a
> variable, dietary Moisture (variable name dMoist).

?quantile
> quantile(rnorm(100),c(0.2,0.4,0.6,0.8,1))
       20%        40%        60%        80%       100%
-1.0023956 -0.2448597  0.2846434  0.8926857  3.0120353