Actually, it works for the a=1 case, not for the others. It still gives
the invalid 'zlim argument' error.
I'll try to work it out maybe instead of NULL giving a c which is
dependent on the max(z).
Daniel
2011-03-30 10:42 keltezéssel, Kehl Dániel írta:
It helped a lot indeed, thank you very much!
Now I understand why it was a problem for persp!
Daniel
2011-03-30 10:31 keltezéssel, Gavin Simpson írta:
On Wed, 2011-03-30 at 09:55 -0700, Kehl Dániel wrote:
Dear David,
I think that is a small bug too, maybe because the function is
constant?
is there a nice way to put the c(0,2.1) argument optionally, only if
all
the parameters are 1?
Should I post the problem somewhere else (developers maybe?)
I don't think this is a bug really; the code is having to compute limits
of the z axis and you supplied it one bit of information: a 2. If your
data are so degenerate then it is not unreasonable to expect some user
intervention. Admittedly, persp doesn't seem to work like other R
plotting functions.
You could do something like:
persp(x1, x2, z,
zlim = if(length(na.omit(unique(as.vector(z))))< 2){ c(0,2.1) }
else { NULL})
in your call to persp so it only uses user-defined limits if the number
of numeric values in z is less than 2.
HTH
G
thanks:
Daniel
2011-03-30 04:42 keltezéssel, David Winsemius írta:
On Mar 29, 2011, at 4:45 PM, Kehl Dániel wrote:
Dear list members,
I want to draw surfaces of Dirichlet distributions with different
parameter settings.
My code is the following:
#<begin code>
a1<- a2<- a3<- 2
#a2<- .5
#a3<- .5
x1<- x2<- seq(0.01, .99, by=.01)
f<- function(x1, x2){
term1<- gamma(a1+a2+a3)/(gamma(a1)*gamma(a2)*gamma(a3))
term2<- x1^(a1-1)*x2^(a2-1)*(1-x1-x2)^(a3-1)
term3<- (x1 + x2< 1)
term1*term2*term3
}
z<- outer(x1, x2, f)
z[z<=0]<- NA
persp(x1, x2, z,
main = "Dirichlet Distribution",
col = "lightblue",
theta = 50,
phi = 20,
r = 50,
d = 0.1,
expand = 0.5,
ltheta = 90,
lphi = 180,
shade = 0.75,
ticktype = "detailed",
nticks = 5)
#<end code>
It works fine (I guess), except for a1=a2=a3=1. In that case I get
the error: Error in persp.default... invalid 'z' limits.
The z matrix has only elements 2 and NA.
Might be a buglet in persp. If you set the zlim argument to c(0,2.1),
you get the expected constant plane at z=2 for those arguments.
Any ideas are appreciated.
Thank you:
Daniel
University of Pécs
______________________________________________
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
