Thanks David and rest of people for replying to my problem posted here. Basically this is my attempt to estimate the variables of a Gaussian random field model using maximum likelihood method. I have examples of using "optim " command to optimize one or more variables in a function, the optim command is implemented in the package Stats4. I am following the manual "Maximum Likelihood Programming in R" by Marco R. Steenbergen.
The study that I am doing involves evaluating variables inside a matrix so I have to pass value to the function as matrix which also contains my variables to optimize. Unfortunately, the manual that I mentioned did not have any examples for my kind of problem. So I hope if you can link my earlier post (forwarded hereunder) with this mail you can get what I am trying to achieve, please let me know if I am still not clear and I will try my best to explain it more. But please do reply. Regards, B.Nataraj -----Original Message----- From: David Winsemius [mailto:dwinsem...@comcast.net] Sent: Thursday, May 31, 2012 8:19 PM To: Nataraj B (ORLL-Biotech) Cc: r-help@r-project.org Subject: Re: [R] Optimizing variables represented in a matrix On May 31, 2012, at 7:37 AM, <nata...@orchidpharma.com> <nata...@orchidpharma.com > wrote: > > Dear R-list members, > > I have a matrix with non-numeric variables in it and I have to > optimize the variables of the matrix in a formula using optim > routine of the stats4 package. I know the matrix can only take > numeric data Some of the things you think you know, are not so: > exvec <- c('0.05V1+V2', '0.31V1', '0.05V1', '0.31V1', '0.3V1+V2', '0.5V1', '0.05V1', '0.5V1', '0.1V1+V2') > matrix(exvec, 3,3) [,1] [,2] [,3] [1,] "0.05V1+V2" "0.31V1" "0.05V1" [2,] "0.31V1" "0.3V1+V2" "0.5V1" [3,] "0.05V1" "0.5V1" "0.1V1+V2" > and so I would like to know how to store non-numeric variables > inside a matrix. > > Say for example: The 3X3 matrix is 0.05V1+V2 0.31V1 > 0.05V1 > 0.31V1 0.3V1+V2 > 0.5V1 0.05V1 > 0.5V1 0.1V1+V2 > > The matrix is only for an example and the real matrix that I want to > use is a 15X15 matrix ,here I would like to optimize the values of > V1 and V2 using a formula. Whether that plan makes sense seems problematic, but that wasn't your question. > > Could you please help me how to go about to represent the matrix in R. I'm guessing you have thoughts of evaluating these expressions. They are not valid R expressions, however. You have some further study to do. -- David Winsemius, MD West Hartford, CT ______________________________________________ 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.
