[R] How to plot contours for joint density of 2 independently distributed r.v.?

rlearner309 unixunix99 at gmail.com
Mon Sep 15 17:10:33 CEST 2008


Wonderful!
THanks a lot!!



Dimitris Rizopoulos-4 wrote:
> 
> do you know the probability density functions for these random variable? 
> If yes, then you need something like the following:
> 
> x <- seq(-5, 5, len = 50)
> y <- seq(0.001, 10, len = 50)
> z <- outer(x, y, function(x, y){
>      dnorm(x) * dgamma(y, 5)
> })
> 
> contour(x, y, z)
> 
> where you replace dnorm() and dgamma() with your pdf's.
> 
> If you just have a sample from X and Y, then you could use kernel 
> density estimation, for instance, check
> 
> help("bkde2D", package = "KernSmooth")
> 
> 
> I hope it helps.
> 
> Best,
> Dimitris
> 
> 
> rlearner309 wrote:
>> X and Y are independently distributed random variables.
>> I would like to study the contours of the joint density of these two
>> variables.
>> Any function to call?
>> 
>> Thank you very much!
> 
> -- 
> Dimitris Rizopoulos
> Assistant Professor
> Department of Biostatistics
> Erasmus University Medical Center
> 
> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> Tel: +31/(0)10/7043478
> Fax: +31/(0)10/7043014
> 
> ______________________________________________
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> 
> 

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