Hi, Is it possible to share the code on this list? I'm also interested (and maybe others to) Or are you planning to make a package?
Best regards Bart Ted.Harding-2 wrote: > > On 12-Oct-09 13:33:17, Ted Harding wrote: >> On 12-Oct-09 13:24:01, Terry Therneau wrote: >>> ---------- begin included -------- >>> Greetings! >>> I want to follow the evolution of a Nelder-Mead function >>> minimisation (a function of 2 variables). Hence each simplex >>> will have 3 vertices. >>> >>> Therefore I would like to have a function which can output >>> the coordinates of the 3 vertices after each new simplex >>> is generated. However, there seems to be no way (which I can >>> detect) of extracting this information from optim() (the 'trace' >>> argument to 'control' does not seem to have provision for this, >>> according to '?optim', and I have tried it out without success). >>> >>> --- end include ----- >>> >>> Why not put a cat() statement into "fn", the function that you supply >>> which optim is calling? That will give the vertices that it tries one >>> by one. >>> >>> Terry T. >> >> That's neat and simple! It hadn't occurred to me. Thanks! >> Ted. > > And, 10 seconds after posting, I realised why it hadn't -- there > would be no visible association between the vertex and the simplex > (in this instance the triangle) that it belongs to. > > In other words, which two other points in the preceding sequence, > along with the current one, make up the triangle being tested? > > Given the complexity of the Nelder-Mead process, it would be very > tricky indeed to try to track this through the sequence of vertices > which cat() would output. > > As it happens, Ben Bolker kindly sent me code which he wrote (see > his earlier mail) which does do this nicely, since it has an output > option within the Nelder-Mead routine itself -- at which point, > the routine itself knows what the simplex is. > > Ted. > > -------------------------------------------------------------------- > E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk> > Fax-to-email: +44 (0)870 094 0861 > Date: 12-Oct-09 Time: 14:45:00 > ------------------------------ XFMail ------------------------------ > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/Nelder-Mead-with-output-of-simplex-vertices-tp25838572p25869383.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
