search for: chemometrics

...updated R in Lenny from http://cran.fiocruz.br/bin/linux/debian/ I included in sources.list: deb http://cran.fiocruz.br/bin/linux/debian lenny-cran/ deb-src http://cran.fiocruz.br/bin/linux/debian lenny-cran/ Then: apt-get update apt-get install r-base r-base-dev Then I downloaded the package chemometrics_0.8.tar.gz from http://cran.r-project.org/src/contrib/chemometrics_0.8.tar.gz After untar I copied the dir chemometrics to /usr/lib/R/library and tried install.package(chemometrics) from R prompt (as root): install.packages(chemometrics) Erro em install.packages(chemometrics) : objeto 'c...

Hello i need some precision about nipals in the chemometrics package in R . When i use nipals in chemometrics i obtain T and P matrix. I really don't understand what to do with these two matrix to obtain the scores for every the component (like in spss fo example) Comp1 Comp2 Comp3 quest1 0,8434 0,54333 0,3466 quest2 0,665...

Maybe someone out there has done this already .... (which would save me some time): For a repetitive chemometric task I need to retrieve spectra from a Nicolet IR acquisition system into R and analyze them there. The raw spectra are in files ending in the extension .spa. I can use the Omnic software to export them to .csv, but I would like to skip this step since it is manual. Has anyone of you

Dear All, A new task view "ChemPhys" on chemometrics and computational physics is available on CRAN (http://cran.r-project.org/web/views/ChemPhys.html). It describes packages and functions that are of use in modeling chemical/physical systems. Suggestions and comments regarding this task view are welcome. If you think a new category, package or fun...

Hi all, I would like to do some QSAR analysis (quantitative structure activity relationship). I need to use some Partial Least Squares (PLS) regression, but I have not seen this option on the R-project. Is it possible to do this kind of regression on R? thank you in advance best regards, olivier [[alternate HTML version deleted]]

...03 day 16 svn rev 62282 language R version.string R version 3.0.0 alpha (2013-03-16 r62282) nickname Unsuffered Consequences > Thanks, Wayne ---------------------------------------------------------------------------------------- Wayne Jones Statistics & Chemometrics Shell Global Solutions (UK) Shell Technology Centre Thornton P.O. Box 1, Chester CH1 3SH, United Kingdom Tel: +44 (0) 151 373 5977 Mobile: +44 (0) 7896 536026 Email: Wayne.W.Jones@shell.com<mailto:Wayne.W.Jones@shell.com> Intranet: Statistics and Chemometrics - Shell Wiki<http://sww.wiki.s...

Dear all, I want to do the following process as a loop ( to run automatically with dimension of X, here 50). How can I do that? Your cooments will be highly appreciable. Alex *# Code:* library(lars) library(chemometrics) X<-matrix(rnorm(2500),ncol=50) dim(X) # [1] 50 50 X1<-X[,2:dim(X)[2]] # I have taken out first column dim(X1) #[1] 50 49 X2<-X1[2:dim(X1)[1],] # new X2 is constructed dim(X2) #[1] 49 49 y<-as.matrix(X1[1,]) # Now first row of the X1 acts a response vector dim(y) # [1] 49 1 #...

...ondescript subject line, but I have two questions: 1. What is a really good book on R for a nonprogrammer? 2. How do I open more than one R Graphics: Device 2(ACTIVE). That what is the R command that I can use to keep more than one plot open. I am running a script from a book on Chemometrics that results in more than one graph during the execution, but it seems that R deletes each graph when the script calls for the next plot. Thanks in advance Stephen P. Molnar, Ph.D. Life is a fuzzy set Foundation for Chemistry...

de Jong, S. (1993) SIMPLS: an alternative approach to partial least squares regression. Chemometrics and Intelligent Laboratory Systems, 18, 251?263 Thanks

Greetings. I'm teaching linear regression this semester and that means I write more functions for my regression support package "rockchalk". I'm at a point now were some fresh eyes would help, so if you are a student in a course on regression, please consider looking over my package overview document here: http://pj.freefaculty.org/R/rockchalk.pdf That tells how you can grab

...king, quite unsuccesfully, for a number of functions/packages. Firstly, I am interested in a package for partial least squares. I have found that there seemed to exist a package called pls, but which seems not to run any more with modern versions of R. I have not been able to find certain "chemometrics package" I found some people discussing about in this list some time ago and that, it seems, included these kind of functions. Secondly, I have not been able to find a function "equivalent" to the SAS procedure STEPDISC which performs a step process (only available for lm and gl...

...f special volumes. They will be guest edited (I have guest editors already, although somewhat tentative in some cases). Each volume will have 5-10 issues (articles) of the usual JSS format. Psychometrics in R Political Methodology in R Econometrics in R Social Science Methodology in R Spectroscopy/Chemometrics in R Ecology in R If you have suggestions, comments, possible contributions, ideas for additional volumes and so on, send them to me and I'll forward them to the appropriate authorities. -- Jan de Leeuw; Distinguished Professor and Chair, UCLA Department of Statistics; Editor: Journal of Mul...

Special Volume on Spectroscopy and Chemometrics in R Guest Edited by Katharine M. Mullen and Ivo H.M. van Stokkum 11 contributions, with software packages and examples Similar volumes on R in Psychometrics (guest edited by Jan de Leeuw) and R in Political Methodology (guest edited by Micah Altman and Simon Jackman) are close to being finished....

Dear R user, I am looking for a code on double cross validation in LASSO , one for optimizing the parameter and other one is for MSEP. If any one have it, please foroward to me. I am using different package like LARS, chemometric etc. Thanks in advance Alex [[alternative HTML version deleted]]

Dear All: I'm a newbie to R and chemometrics. Now I'm trying apply bclust on fuzzy c-means like this: >bc1 <- bclust(iris[,1:4], 3, base.centers=20,iter.base=100, base.method="cmeans") Committee Member: 1(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)Erro r in bclust(iris[, 1:4], 3, base.centers = 2...

...dation on the complete data set (n = 174). I need to use 10 folds and repeat the cross-validation 100 times. In the end of the procedure, I need to have access to the predicted values for each observation, that is, to the 100 predicted values for each observation. The function lmCV() in the package chemometrics provides the predicted values. However, it works only with multiple linear regression models. I hope there is a way of doing it. Best regards, ----- Bc.Sc.Agri. Alessandro Samuel-Rosa Postgraduate Program in Soil Science Federal University of Santa Maria Av. Roraima, n? 1000, Bairro Camobi, CEP 97...

...dels obtained in the Y-randomization have relatively high R2 and high q2 then it implies that an acceptable regression model cannot be obtained for the given data set by the current modelling method. I cannot find any references to Y-randomization or Y-scrambling anywhere in the literature outside chemometrics/QSAR. Any links or references would be much appreciated. Thanks in advance. DK ---------------------------------------------- Damjan Krstajic Director Research Centre for Cheminformatics Belgrade, Serbia ---------------------------------------------- _______________________________...

Dear list members; The code given below corresponds to the PCA-NIPALS (principal component analysis) algorithm adapted from the nipals function in the package chemometrics. The reason for using NIPALS instead of SVD is the ability of this algorithm to handle missing values, but that's a different story. I've been trying to find a way to improve (if possible) the efficiency of the code, especially when the number of components to calculate is higher than 100....

...I now manually cut and paste to have 10 - 15 arguments in the order function. There has to be a clever way to do this... Ron -----------------------+-------------------------------------------------- Ron Wehrens | " In a purely metaphorical sense, I am a turnip " Dept. of Chemometrics | (W.A. Quayle) University of Nijmegen | Email: rwehrens at sci.kun.nl Toernooiveld 1 | http://www-cac.sci.kun.nl/cac/rwehrens 6525 ED Nijmegen | Tel: +31 24 365 2053 The Netherlands | Fax: +31 24 365 2653 --------------...

There is a very useful and apparently fundamental feature of R (or of the package pls) which I don't understand. For datasets with many independent (X) variables such as chemometric datasets there is a convenient formula and dataframe construction that allows one to access the entire X matrix with a single term. Consider the gasoline dataset available in the pls package. For the model