(INTRO.DISTR) {distr} | R Documentation |
``distr'' is a package for R from version 1.8.1 onwards that is distributed under GPL license 2.0. Its own current version is 1.5. It requires package setRNG by Paul Gilbert, pgilbert@bank-banque-canada.ca, to be installed from
http://cran.r-project.org/mirrors.html
The aim of this package is to provide a conceptual treatment of random variables (r.v.'s) by means of S4 classes.
A mother class Distribution
is introduced with slots for a parameter and —most important—
for the four constitutive methods r
, d
, p
, and q
for simulation respectively for evaluation of
density / c.d.f. and quantile function of the corresponding distribution. All distributions of the base package for which corresponding
r
-, d
-, p
-, and q
-functions exist (like normal, Poisson, etc.)
are implemented as subclasses of either AbscontDistribution
or DiscreteDistribution
,
which themselves are again subclasses of Distribution
.
This approach seems very appealing to us from a conceptual viewpoint:
Just pass an object of some derived distribution class to a generic function as argument and let the dispatching mechanism decide what to do on run-time.
As an example, we may automatically generate new objects of these classes with corresponding
r
, d
, p
, and q
-slots for the laws of r.v.'s under standard mathematical
univariate transformations and under convolution of independent r.v.'s. For Distribution
objects X
and Y
expressions like
3*X+sin(exp(-Y/4+3))
have their natural interpretation as corresponding image distributions.
Additionally, we also provide classes for a standardized treatment of simulations (also under contaminations) and evaluations of statistical procedures on such simulations. A somewhat longer and more detailed manual can be obtained under
http://www.uni-bayreuth.de/departments/math/org/mathe7/DISTR/
library("distr")