[R] Help with filled.contour()

[Jeffrey Horner]

Dieter Menne wrote:
> Michael Kubovy <kubovy <at> virginia.edu> writes:
> 
>> I tried and it gave a strange result. See
>> http://people.virginia.edu/~mk9y/mySite/twoGaussian.R
>> and
>> http://people.virginia.edu/~mk9y/mySite/twoGaussian.pdf
>>
>> *********************************
>> Session Info
>> *********************************
>>  > sessionInfo()
>> R version 2.4.1 (2006-12-18)
>> powerpc-apple-darwin8.8.0
> 
> Hmm, strange, I can reproduce your problem on Windows (otherwise same config)
> with pdf, but it looks beautifully on screen for me if I mentally remove the
> ugly legend.


Try the image function. The smoothness of the plot will be proportional 
to the length of x and y. For instance 200 isn't bad:

mu1 <- 0
mu2 <- 5
s <- 1
x <- seq(-2.5, 7.5, length = 200)
y <- seq(-2.5, 2.5, length = 200)
f <- function(x,y){
     term1 <- 1/(2*pi*sqrt(s*s))
     term2 <- -1/2
     term3 <- (x - mu1)^2/s
     term4 <- (y - mu1)^2/s
     term5 <- (x - mu2)^2/s
     term1*(.5 * exp(term2*(term3 + term4)) + .5 * exp(term2*(term5 + 
term4)))
} # setting up the function of the multivariate normal density
z <- outer(x, y, f)
# persp(x, y, z)
require(grDevices)
#pdf('twoGaussian.pdf')
#filled.contour(x, y, z, axes = F, frame.plot = F, asp = 1,
#               col = gray(seq(0, 0.9, len = 25)), nlevels = 25)
image(x,y,z,col=gray(seq(0,0.9,len=200)))

Cheers,

Jeff
-- 
http://biostat.mc.vanderbilt.edu/JeffreyHorner