[R] Plotting the Log-Likelihood
Dear Users,
I would like to plot the log-likelihood (depending on two
parameters).
I wrote the following code:
library(mvtnorm)
sigma<-
matrix(c(4,2,2,3),ncol=2)
x<-rmvnorm(n=500,mean=c(1,2),sigma=sigma)
likel<-
function(param,data){
pos1<-which(data[,1]<0)
pos2<-which(data[,1]>=0)
#density
dens<-rep(0,nrow(data))
dens[pos1]<-dmvnorm(data[pos1,])
*param[1]
dens[pos2]<-dmvnorm(data[pos2,])*param[2]
#return log-
likelihood
sum(log(dens))
}
#plotting the log-likelihood
param1<-
seq(from=0,to=1,length=200)
param2<-seq(from=0,to=1,length=200)
combin<-
as.matrix(expand.grid(param1,param2,KEEP.OUT.ATTRS=FALSE))
likel.values<-
apply(combin,1,likel,data=x)
matr.likel.values<-matrix(likel.values,200,200)
persp(param1,param2,matr.likel.values,
xlab="param1",ylab="param2",
zlab="Likelihood",
theta=5,phi=20,expand=0.5,
col="lightblue",
ltheta=120,shade=0.75,ticktype="detailed")
It is all ok, but I am searching
for a new "lighting" way in order to earn time.
I need an alternative function
for apply(), when I calculate the log-likelihood for every single couple of
values (param1,param2).
Do you have any ideas?
Thank you in advance,
Enrico Foscolo
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[R] Including greek letters in a pairs() plot
Good Morning,
I have a stupid problem about inclusion of greek letters in a
plot built with function pairs().
First of all, I have a matrix with 3 columns
and 1000 rows and I would like to use pairs() in order to plot points in the
upper panel and to compute correlation in the lower panel.
In the lower panel
I would like to see the following text in each ij-plot: hat(rho)[i,j]=cor(x,y).
Obviously, rho should be written in according to greek alphabet.
This is my
function:
panel.cor <- function(x,y){
cor<-0
cor<-round(cor(x,y),4)
text
(0.5,0.5,cor,cex=2)
}
Thank You very much,
Enrico Foscolo
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and provide commented, minimal, self-contained, reproducible code.
[R] Find a zero of a composition of functions
Good morning to all,
I should find the zero of a specific function,
func(x,f.
me,c,t)=x+f.me*c-t
where 'c' and 't' are constants and 'f.me' is an other
function of 'x'.
Actually, I am interested in considering 'f.me' as an
expression().
Namely,
uniroot.me<-function(f.me,c,t){
func<-function(x,
f.me,c,t) x+eval(f.me)*c-t
uniroot(func,c(0,1),f.me=f.me,c=c,t=t)$root
}
uniroot.me(expression(x*(1-x)),c=1,t=1)
For instance, let me suppose
that 'f.me=expression(x^a*(1-x))'. How should I do in order to introduce the
new constant 'a' in function 'uniroot.me'?
Thank you very much,
Enrico
Foscolo
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and provide commented, minimal, self-contained, reproducible code.
[R] Two or more dimensional root (Zero) finding
Good morning to all, I should find the zero of a specific function with respect to a vector of arguments. Does it exist something similar in R? Thank you very much, Enrico Foscolo __ 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.
[R] Function able to identify the row and the column in a matrix
Good morning to all, I should evaluate a function for every cell of a given matrix with n rows and n columns. This function, named fun(), has got two arguments: the number of the row and the number of the column which characterized every single cell. So the result should be fun(1,1) fun(1,2) ... fun(1,n) fun(2,1) fun(2,2) ... fun(2,n) ......... ... fun(n,1) fun(n,2) ... fun(n,n) Does it exist a function which could build this new matrix, where each element in the cell (i,j) is fun(i,j), with 1<=i, j<=n? Thank you very much, Enrico Foscolo __ 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.
[R] Function able to identify the row and the column in a matrix
Good morning to all, I should evaluate a function for every cell of a given matrix with n rows and n columns. This function, named fun(), has got two arguments: the number of the row and the number of the column which characterized every single cell. So the result should be fun(1,1) fun(1,2) ... fun(1,n) fun(2,1) fun(2,2) ... fun(2,n) ......... ... fun(n,1) fun(n,2) ... fun(n,n) Does it exist a function which could build this new matrix, where each element in the cell (i,j) is fun(i,j), with 1<=i, j<=n? Thank you very much, Enrico Foscolo __ 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.
[R] Color Function
Good Morning to Everybody, I am searching a function which could define a vector of colors from a vector of gray, from white to black (not from black to white as the function gray()). I have to use it in the function image(), parameter "col". Thank You very much, Enrico Foscolo __ 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.
