similar to: [OT] two question about color space.

Dear R users, I am a newbie. Just switched from MATLAB. So thanks a lot for your patience. I have 50000 spectra collected in field. Each spectra has two columns : Wavelength (56) and the actual measurement. Each measurement came in a different .txt file on disk (50000 files in total). I wrote a script that reads every spectra in a for loop and constructs two variables : Wavelength (56) and

grDevices::convertColor has arguments 'from' and 'to' which can take on value 'XYZ'. Can someone confirm that 'XYZ' is the same as the CIE chromaticity coordinates that are also sometimes refered to as 'xyY' in the literature? Or are these the CIE tristimulus values? It looks to me like the first case is true, but I would appreciate hearing from one of

Hi I'm trying to write a generic script for processing some data which finishes off with some plots. Given Im never sure how many columns will be in my dataframe I wanted to using the following plot(spectra.wavelength, cormat, type = "l", ylim=c(-1,1), xlab="Wavelength (nm)", ylab="Correlation") however even if I specify as type="l" it appears plot

Hi, I am currently analysis Raman spectroscopic data with the hyperSpec package. I consulted the documentation on this package and I found an example work-flow dedicated to Raman spectroscopy (see the address : http://hyperspec.r-forge.r-project.org/chondro.pdf) I am currently trying to remove outliers thanks to PCA just as they did in the documentation, but I get a message error I can't

Hi there, I hope to draw a plot like this: http://www.sg-chem.net/swizard/Ru-bqdi-spectra.gif is it possible to draw it using R? thanks for any suggestions. regards, Jinsong

I am not sure if I should ask this question in this list. But I'll try. Currently I am trying to analyze images using EBImage and biOps. One of the features that I need to extract from various images is the color spectrum, namely, which colors each image consists of. So, each image hopefully can be converted into some sort of color histogram so that color ingredients are easily comparable

Hello, I'm still a newbie user and struggling to automate some analyses from SigmaPlot using R. R is a great help for me so far! But the following problem makes me go nuts. I have two spectra, both have to be fitted to reference data. Problem: the both spectra are connected in some way: the stoichiometry of coefficients "cytf.v"/"cytb.v" is 1/2. {{In the SigmaPlot

Dear all, I work with (vibrational) spectra: some kind of intensity (I) over frequency (nu), wavelength or the like. I want to do fourier transform for interpolation, smoothing, etc. My problem is that the spectra are often irregularly spaced in nu: the difference between 2 neighbouring nu varies across the spectrum, and data points may be missing. Searching for discrete fourier transform

Dear list, I'd like to ask for some advice in creating a wrapper function for this C code, http://www.fourmilab.ch/documents/specrend/ http://www.fourmilab.ch/documents/specrend/specrend.c I could probably port it in R, but I've been hoping to use compiled code for a while and this looks like a good test case. Unfortunately, the only success I've had so far is with the too

It appears that the chromatic adaptation feature of `grDevices::convertColor`is broken, and likely has been for many years.? While a little surprising, it is an obscure enough feature that there is some possibility this is actually broken, as opposed to user error on my part.? If it turns out to the latter, I apologize in advance for spamming this list. Consider: ??? rgb.in <-

`grDevices::convertColor` performance can be improved by 30-300x with small changes to the code. `colorRamp(space='Lab')` uses `convertColor` so it too benefits from substantial performance gains. `convertColor` vectorizes explicitly over the rows of the input color matrix using `apply`. The level-1 patch [1] illustrates a possible minimal set of changes to achieve this with just R

Dear list, I've recently become interested in comparing the spectral estimates using the different methods ("pgram" and "ar") in the spectrum() function in the stats package. With many thanks to the authors of these complicated functions, I would like to point out what looks to me like a bit of an inconsistency -- but I would not be surprised if there is good reasoning

Hello all, Before getting to my question, I would like to apologize for asking this question here. My question is not directly an R question, however, I still find the topic relevant to R community of users - especially due to only * partial* (current) support for interactive data visualization (see here: http://cran.r-project.org/web/views/Graphics.html were with iplots we are waiting for

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 =

Hi, I'm trying to match peaks between chromatographic runs. I'm able to match peaks when they are chromatographed with the same method, but not when there are different methods are used and spectra comes in to play. While searching I found the ALS package which should be usefull for my application, but I couldn't figure it out. I made some dummy chroms with R, which mimic my actual

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

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:

Hi, I'm new to R and looking for a way to use a variable to reference to an object. I'm plotting several graphs on top of each other and want to do this by a for loop. The field I want to graph have names like a1,a2,a3, ... I can't figure out how to get this working: It should look like this: lines(spectral$Wavelength,paste("spectral$a",j,sep=""),col=j) but

Hi, I have some difficulty in figuring out whether I am doing correct or not. A brief introduction about the work: It is a light/dark choice test conducted in insect larvae.  The response is binary (0- present in dark area, 1-present in light area) and the experiment is run for 15 min, so there are 15 repeated measurements per individual larva at 1 min intervals.  The factors which affect

First time ever that I try to call subroutines in a Win DLL using R. Have done this before using VBA and Python. The C code's function argument list contains only double pointers (double *x). The function is declared void, the output value is one of the arguments. C calling sequence is used. When inspecting the exports of the DLL with dumpbin I can see that the function I need is