similar to: filtering spectra

This problem is not limited to R, but R is one of the packages in which it arises. princomp is a nice function which creates an object for which inspection methods have been written. Unfortunately, princomp does not admit cases in which the x matrix is wider than high (i. e. more variables than observations). Such cases are typical in spectroscopy and related disciplines. It would be nice if the

... I checked and Brian and I are both right (see bottom for prior mail exchange). Let me explain: ============================================================= 1. Indeed, in principle, princomp allows data matrices with are wider than high. Example: > x1 [,1] [,2] [,3] [,4] [1,] 1 1 2 2 [2,] 1 1 2 2 > princomp(x1) Call: princomp(x = x1) Standard deviations:

... I checked and Brian and I are both right (see bottom for prior mail exchange). Let me explain: ============================================================= 1. Indeed, in principle, princomp allows data matrices with are wider than high. Example: > x1 [,1] [,2] [,3] [,4] [1,] 1 1 2 2 [2,] 1 1 2 2 > princomp(x1) Call: princomp(x = x1) Standard deviations:

This message is for people who know the mechanics of model.frame within lm. I am fitting lm models for different responses on a data frame which has (at least some) factors. As it happens, some of the responses are NA for some of the factor levels. Logically, lm creates an xlevels list for which the length of levels is different from the original number of levels in the data frame (a

Here is the first one. It concerns the handling of multiple offsets. The following lines creates a list with 3 explanatory variables and one response. > x<-seq(0,1,length=10);y<-sin(x);z<-cos(x); w<-x+y+z+rnorm(x) > data<-list(x=x,y=y,z=z,w=w) A lm is fitted with one explanatory variable and two offsets. So far, so good. >

The result of > plot(c(-1,1),c(-1,1),type="n") > arrows(0,0,1,1) > arrows(0,0,0,0) is not what I expected. The first arrow is drawn correctly. The second does not collapse to a point but goes from (0,0) off to (-infinity,infinity). I guess something is divided by zero in the internal function. Chris. =============================================== platform Windows arch

This might be easy (but I didn't find an answer in the archives). I'm trying to make nice looking images (using image()). To make them look nice (not jagged), it usually takes me at least 100x100 points. This can be slow for frequent redraws. Is there a smarter (less point intensive) way? I was thinking in terms of hexabins, for example, which for much less jagged looking regions,

look at the spectrums before you do the cbind - I would not suggest letting R wrap the data to fill in a data frame. I would suggest using something that you "know how it acts" in the frequency domain like zero. You are probably introducing periodicies that are not real, and I would suggest not to go down this path. As for finding commonalities amongst signals- it all depends on what

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, This is potentially a bug in spec.pgram, when the number of samples is odd,spec.pgramreturns a different result withfast = TRUE, the example below contains the two varieties with a reference spectrum calculated manually. the number of returned spectra is also larger (50 compared to 49) whenfast = TRUE x <- rnorm( 99 ) plot(spec.pgram(x, taper = 0 , detrend = FALSE , plot =

Hi to all who suffer from rterm not shutting down in xemacs/ESS on windows NT or 2000. Also hi to those who could eventually help. Here is some more information which could help and some ENCOURAGEMENT to contribute to a solution. 1. It may be an xemacs problem but it is more likely an interaction between rterm/comint/and xemacs. In fact, the problem started occurring around version R 1.6.0. I

There is a little problem in handling logicals in RMySQL: # here is the MySQL connection > con <MySQLConnection:(1816,0)> # here is the data frame > print(a<-data.frame(x=c(TRUE,FALSE),y=c(FALSE,TRUE))) x y 1 TRUE FALSE 2 FALSE TRUE # as promised, the two data frame columns are identified as logicals and # the field types are set to tinyint > field.types <-

Hi all, I need to insert the name of spectra in a stacked plot obtained with hyperspec. I use this command plot(spectra [c(-1:-4, -6:-8, -10:-12, -14:-16)], stacked = T) but, in this way R draw nameless spectra on the Y axis. How can I solve the problem? Thank you for any suggestion. Best regards, Roberto -- View this message in context:

I would really appreciate it if someone can give suggestions on how to do spectra fitting in R using ordinary least square fitting and non-negativity constraints. The lm() function works well for ordinary least square fitting, but how to specify non-negativity constraints? It wouldn't make sense if the fitting coefficients coming out as negative in absorption spectra deconvolution. Thanks.

Hi Folks... No code to troubleshoot here. I need some suggestions about the right terminology to use in further searching, and any suggestions about R pkgs that might be appropriate. I am in the planning stages of a project in which IR, NMR and other spectra (I'm a chemist) would be collected on various samples, and individual samples would be followed over time. The spectra will be feature

Has anyone seen an official announcement to DSC-2005. I saw and email exchange on the R-news list in mid January in which a date was announced unofficially. (to DSC-organizers: we need and "official" announcement to request funding and travel permission and flights from Europe to Seattle are starting to fill up, so this is urgent). Christian Ritter Functional Specialist Statistics Shell

Dear collegues, I´ ve worked with near infrared (NIR) spectroscopy to assess chemical, physical, mechanical and anatomical properties of wood. I use "The Unscrambler" software to correlate the matrix of dependent variables (Y) with the matrix of spectral data (X) and I would like to migrate to R. The matrix of spectral variables is very large (2345 columns and n lines, where n =

For some time now I use a modified version of names (extract direction) of the following type: Names<- function (x,filter="^") { grep(filter,names(x),value=TRUE) } Request: Has anyone already written a version which goes the other way (that is, which allows assignment of the type Names(x,filter)<-...). Naive versions are obvious, but I think something would have to be done

If you are saying other programs are saying this as well it could be your windows system got corrupted and is not reporting mtime correctly to underlying programs. Try on a fresh install of windows or some other computer to be sure. On Thu, Apr 7, 2016 at 2:34 PM, Jeff Sadowski <jeff.sadowski at gmail.com> wrote: > If your file is unchanged and the modified time is unchange in both ls

R-2.1.1 on windows XP I just noticed something unpleasant when using bwplot (from lattice). In order to satisfy a wish from a client, I needed to produce sets of boxplots conditioned by another factor. My client didn't like the look of the boxplots (by default, they have a star to mark the median, instead of the commonly used line). I told him "no problem" dumped panel.bwplot,