OK, with this information I can tell you that PDL::Transform is probably not what you want--that does coordinate transforms (I was interpreting your question as in, "can I scale things (images, coordinates, etc) in multiple dimensions"). Thank you for the MDS wikipedia link.
PCA might be a better search term. Look at Maggie's PDL::Stats module, which contains PDL::Stats::GLM. That includes some PCA routines. I don't know that GSL does PCA explicitly, but it should handle the eigenvalue or SVD portions of PCA just fine. There are some PDL::GSL:: modules but I don't think they include the eigen calculations. PDL::Slatec has the 'eigsys' function which may also be helpful. PDL::MatrixOps has the eigens. These last two I found by doing $pdldoc -a eigen from the command line after PDL was installed. There is a general R/Splus <--> Perl package here: http://www.omegahat.org/RSPerl/ but it has not been updated in many years, and I have never used it. best, Derek On Jan 31, 2013, at 1:52 PM, Jean Véronis wrote: > Thanks Derek, I am going to check PDL::Transform right away. > > My need is to reduce dimensionality on large distance matrices. For this is > use multidimensional scaling > (http://en.wikipedia.org/wiki/Multidimensional_scaling) by calling R from > perl (cmdscale function : > http://stat.ethz.ch/R-manual/R-patched/library/stats/html/cmdscale.html). > > It's perfectly fine, expect in terms of performance, since at the moment I > didn't find any better way than use Statistics:R, which basically passes data > through stdin/stdout. When it comes to huge matrices, it is extremely > inefficient. Hence my question. > > I tried to google "pdl multidimensional scaling", "gsl multidimensional > scaling", "perl multidimensional scaling", and all possible variants > involving "pcinipal coordinates analysis", "PCoA", with no success. > > Many thanks, again. > --j > > Le 31 janv. 2013 à 21:41, Derek Lamb <[email protected]> a écrit : > >> Hi Jean, >> >> The best hint I can provide based on the extremely limited information you >> have given is PDL::Transform. >> >> You might get a better response if you describe what you are trying to do in >> more than one sentence, what you have tried, whether you are new to PDL or >> Perl or are already using one or both, and what documentation you have >> looked at. >> >> best, >> Derek >> >> On Jan 31, 2013, at 1:24 PM, Jean Véronis wrote: >> >>> Hi all, >>> >>> I am looking for a multidimensional scaling package. >>> Any hint would be appreciated. >>> >>> Many thanks >>> --j >> >
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