Re: [R] Optim stripping attributes from relistable objects
On Mon, 18 Aug 2008, Katharine Mullen wrote: The following code is inspired by the help file for the relist() function (see?relist), which explicitly details how you can use a The example is in the 'Details' section and, indeed, it looks like it no longer works. I don't think it ever did (after all there is a comment that dnorm does not have the parameters stated). The subject line here illustrates the misunderstanding. Optim *strips* nothing -- it creates a new object to pass to the function. The help says Any names given to 'par' will be copied to the vectors passed to 'fn' and 'gr'. Note the use of 'copy' here. You cannot assume that any other attributes will be copied, and this behaviour has not been changed (except to add names in March 2006, well before relist() was added), AFAICS. relistable object in conjunction with optim to pass and reconstruct complex parameter structures/groupings. The idea is that the optim() function can only work with vectors, but in many cases you would like to use a complex structure inside the objective function- relist is one way to do that. The problem is that optim appears to be stripping the attributes and therefore the example doesn't seem to run, giving the error at the bottom. You can get around this by specifying skeleton for relist: rb.banana - function(params) { params - relist(params, skeleton=list(x=NA,y=NA)) return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) } ipar - as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) xx - optim(unlist(initial.params), rb.banana) rb.banana - function(params) { + #Params is initially a vector + cat(Params initially has the attributes:\n) + print(names(attributes(params))) + #Relisting it turns it into a list... + params - relist(params) + cat(-\n) + #..which can then be called in the standard list manner + return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) + } ipar- as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) #Test to see if rb.banana works properly in the normal case rb.banana(initial.params) Params initially has the attributes: [1] namesskeleton - [1] 62516 #OK, that's good. How about with optim though? optim(initial.params,rb.banana) Params initially has the attributes: [1] names Error in relist(params) : The flesh argument does not contain a skeleton attribute. Either ensure you unlist a relistable object, or specify the skeleton separately. What's going on here? Has this functionality been removed and the documentation in relist() not updated? Or has the feature been broken? Or have I misinterpreted something here (it wouldn't be the first time!!) Am running R version 2.7.1 (2008-06-23) under windows. Cheers, Mark __ 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-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. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ 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.
Re: [R] Optim stripping attributes from relistable objects
On Mon, 18 Aug 2008, [EMAIL PROTECTED] wrote: Ok - there is an easy work-around by just to passing the skeleton to the objective function. But would it be possible to clarify this point in the relist() help file please (specificaly the example I would think), implies that attributes are copied through by optim and that this is expected behaviour? Already done. You can always check the current version on the SVN server, here https://svn.r-project.org/R/branches/R-2-7-branch/src/library/utils/man/relist.Rd Thanks, Mark 2008/8/18 Prof Brian Ripley - [EMAIL PROTECTED] : On Mon, 18 Aug 2008, Katharine Mullen wrote: The following code is inspired by the help file for the relist() function (see?relist), which explicitly details how you can use a The example is in the 'Details' section and, indeed, it looks like it no longer works. I don't think it ever did (after all there is a comment that dnorm does not have the parameters stated). The subject line here illustrates the misunderstanding. Optim *strips* nothing -- it creates a new object to pass to the function. The help says Any names given to 'par' will be copied to the vectors passed to 'fn' and 'gr'. Note the use of 'copy' here. You cannot assume that any other attributes will be copied, and this behaviour has not been changed (except to add names in March 2006, well before relist() was added), AFAICS. relistable object in conjunction with optim to pass and reconstruct complex parameter structures/groupings. The idea is that the optim() function can only work with vectors, but in many cases you would like to use a complex structure inside the objective function- relist is one way to do that. The problem is that optim appears to be stripping the attributes and therefore the example doesn't seem to run, giving the error at the bottom. You can get around this by specifying skeleton for relist: rb.banana - function(params) { params - relist(params, skeleton=list(x=NA,y=NA)) return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) } ipar - as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) xx - optim(unlist(initial.params), rb.banana) rb.banana - function(params) { + #Params is initially a vector + cat(Params initially has the attributes:\n) + print(names(attributes(params))) + #Relisting it turns it into a list... + params - relist(params) + cat(-\n) + #..which can then be called in the standard list manner + return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) + } ipar- as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) #Test to see if rb.banana works properly in the normal case rb.banana(initial.params) Params initially has the attributes: [1] namesskeleton - [1] 62516 #OK, that's good. How about with optim though? optim(initial.params,rb.banana) Params initially has the attributes: [1] names Error in relist(params) : The flesh argument does not contain a skeleton attribute. Either ensure you unlist a relistable object, or specify the skeleton separately. What's going on here? Has this functionality been removed and the documentation in relist() not updated? Or has the feature been broken? Or have I misinterpreted something here (it wouldn't be the first time!!) Am running R version 2.7.1 (2008-06-23) under windows. Cheers, Mark __ 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-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. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ 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] Optim stripping attributes from relistable objects
Dear all, The following code is inspired by the help file for the relist() function (see?relist), which explicitly details how you can use a relistable object in conjunction with optim to pass and reconstruct complex parameter structures/groupings. The idea is that the optim() function can only work with vectors, but in many cases you would like to use a complex structure inside the objective function- relist is one way to do that. The problem is that optim appears to be stripping the attributes and therefore the example doesn't seem to run, giving the error at the bottom. rb.banana - function(params) { + #Params is initially a vector + cat(Params initially has the attributes:\n) + print(names(attributes(params))) + #Relisting it turns it into a list... + params - relist(params) + cat(-\n) + #..which can then be called in the standard list manner + return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) + } ipar- as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) #Test to see if rb.banana works properly in the normal case rb.banana(initial.params) Params initially has the attributes: [1] namesskeleton - [1] 62516 #OK, that's good. How about with optim though? optim(initial.params,rb.banana) Params initially has the attributes: [1] names Error in relist(params) : The flesh argument does not contain a skeleton attribute. Either ensure you unlist a relistable object, or specify the skeleton separately. What's going on here? Has this functionality been removed and the documentation in relist() not updated? Or has the feature been broken? Or have I misinterpreted something here (it wouldn't be the first time!!) Am running R version 2.7.1 (2008-06-23) under windows. Cheers, Mark __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Optim stripping attributes from relistable objects
The following code is inspired by the help file for the relist() function (see?relist), which explicitly details how you can use a The example is in the 'Details' section and, indeed, it looks like it no longer works. relistable object in conjunction with optim to pass and reconstruct complex parameter structures/groupings. The idea is that the optim() function can only work with vectors, but in many cases you would like to use a complex structure inside the objective function- relist is one way to do that. The problem is that optim appears to be stripping the attributes and therefore the example doesn't seem to run, giving the error at the bottom. You can get around this by specifying skeleton for relist: rb.banana - function(params) { params - relist(params, skeleton=list(x=NA,y=NA)) return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) } ipar - as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) xx - optim(unlist(initial.params), rb.banana) rb.banana - function(params) { + #Params is initially a vector + cat(Params initially has the attributes:\n) + print(names(attributes(params))) + #Relisting it turns it into a list... + params - relist(params) + cat(-\n) + #..which can then be called in the standard list manner + return( (1-params$x)^2 + 100*(params$y - params$x^2)^2) + } ipar- as.relistable(list(x=5,y=0)) initial.params - unlist(ipar) #Test to see if rb.banana works properly in the normal case rb.banana(initial.params) Params initially has the attributes: [1] namesskeleton - [1] 62516 #OK, that's good. How about with optim though? optim(initial.params,rb.banana) Params initially has the attributes: [1] names Error in relist(params) : The flesh argument does not contain a skeleton attribute. Either ensure you unlist a relistable object, or specify the skeleton separately. What's going on here? Has this functionality been removed and the documentation in relist() not updated? Or has the feature been broken? Or have I misinterpreted something here (it wouldn't be the first time!!) Am running R version 2.7.1 (2008-06-23) under windows. Cheers, Mark __ 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-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.