similar to: How do I "normalise" a power spectral density analysis?

I have done a fair bit of spectral analysis, and hadn't finished collecting my thoughts for a reply, so hadn't replied yet. What exactly do you mean by normalize? I have not used the functons periodogram or spectrum, however from the description for periodogram it appears that it returns the spectral density, which is already normalized by frequency, so you don't have to worry about

Hello, I'm fitting general linear models using the function lme() from the package nlme. My variables include a number of covariates and a single random factor, because the experiment was laid out in blocks. I'd like to have a statistic to measure the "proportion of explained variance" from my models. With ordinary multiple regression I'd use R-squared, but I can't

Dear Tom, Short answer, if your using spec.pgram(), use the smoothing kernel to get a better estimate at the frequency centered in the bandwidth. If your frequency bin of interest is wider than the bandwidth of the kernel, average across frequencies (I think). The estimate appears to be normalized already. If you are calculating your PSD independently, then oversample (e.g. 2, perhaps 4 or more

Hi everyone I was using spline to interpolate single or two consecutive missing data points in time series. However, when it comes to longer gaps in the data the spline function generate new data for both my known and unknown data (see below). Aside from not understanding why this happens, I thought thought I might try function "aspline" in library (akima). However, I cannot install or

Ok, I have reinstalled R-1.9.0 and this appears to have fixed the problems I was having with png(). However, I have a further question regarding png() Is it possible to pass a par() argument to the png() command? I am wanting to produce 4 plots per object, which I normally acheive on an X window by par(mfrow=c(1,4)). I have tried calling a new plot and setting par in this way but this has no

Hi, Just a quick query - if I'm creating a function to produce a number of histograms per page of output (one per column from a matrix), how can I pass the column name of the matrix into the title (or indeed to form part of the x-axis label)? TIA, Laura Laura Quinn Institute of Atmospheric Science School of Earth and Environment University of Leeds Leeds LS2 9JT tel: +44 113 343 1596 fax:

Hello, I requested help a couple of weeks ago creating a dipole field in R but receieved no responses. Eventually I opted to create a 3d sinusoidal plot and concatenate this with its inverse as a means for a "next best" situation. It seems that this isn't sufficient for my needs and I'm really after creating a continuous 3d gaussian mesh with a "positive" and

Hi guys, I hope you can help me with this (probably) simple query: I have a data frame: -------------------------- a=c(1,1,1,1,1,1,2,2,2,2,2,2) b=c(1,1,1,2,3,4,1,1,2,2,3,4) c=c(400,200,300,100,500,300,200,100,500,400,200,100) data=data.frame(a=a,b=b,c=c) -------------------------- And I would like to get the following output: -------------------------- b a 1 2 3 4 1 900 100 500 300 2

Hi all, Thanks in advance for any help. I have a vector "b": b=c(1,1,1,2,3,4,3,2,1,1,1,1,1,2,3,4,5,4,3.5,3,2,1,1,1) Imagine b is river flow throughout time. I would like some code that will generate the following information: number of individual 'periods' where b>1 (= 2 in this case) period 1 length = 5, max = 4 period 2 length = 8, max = 5 I can't figure anything

Hi there, Does anyone know of a statistical test for heteroscedasticity for an object of class "gls"? (or alternative objective methods). Thanks in advance, Ben Gillespie, Research Postgraduate o-------------------------------------------------------------------o School of Geography, University of Leeds, Leeds, LS2 9JT o-------------------------------o http://www.geog.leeds.ac.uk/

Hello, Is there a simple way of stacking/merging two dataframes in R? I want to stack them piece-wise, not simply add one whole dataframe to the bottom of the other. I want to create as follows: x.frame: aX1 bX1 cX1 ... zX1 aX2 bX2 cX2 ... zX2 ... ... ... ... ... aX99 bX99 cX99 ... zX99 y.frame: aY1 bY1 cY1 ... zY1 aY2 bY2 cY2 ... zY2 ... ... ... ... ... aY99 bY99 cY99 ...

Hi, I was wondering if anyone could tell me why prcomp() will "Invent" modes of variation in a PCA on identical replicates of data? I would have expected 50 (or whatever number) of identical replicates to return a null score in such an analysis (or at the least, all variables would share the same PC score). This is not the case and I was wondering could someone point me in the direction

Hi all, I'm having problems finding the correct format for a command. I would like to write some text on a plot. I'm using the following command: text(x,y,"text here", srt=90) I would like the text to read: capacity 10^3 m^3 (with ^ denoting superscript (i.e. each '3' as superscript). I've tried fiddling around with expression(paste(etc.... to no avail. I

Hi, I was wondering if anyone might be able to help. I am trying to run R on a remote machine, part of the model run I am attempting writes an external file output as a png (about 48 iterations per model run). I am running R 1.9.1 on SuSe9.0, and am accessing this via ssh from a Debian machine. Initially I used the command ssh -X IP.address and whilst I was able to run the model successfully the

Hi guys, It would be great if you could help me with this one... I'm looking to create a script to convert a matrix of species abundance e.g: <http://r.789695.n4.nabble.com/file/n4643978/species_matrix.jpg> into two vectors e.g: <http://r.789695.n4.nabble.com/file/n4643978/communitylist.jpg> ---------------- If you feel there is no easy answer to this and that it would be

I hope you can help with this one. I have two matricies: 1. A species abundance matrix: <http://r.789695.n4.nabble.com/file/n4643979/2species_matrix.jpg> 2. A species trait score matrix: <http://r.789695.n4.nabble.com/file/n4643979/2trait_matrix.jpg> The trait matrix lists trait scores for each species as listed in the species abundance matrix. I would like to create a script

Hi, I'm having a mental block as to how I can automatically assign filenames to the output of the following code. I am wishing to create a separate .png file for every image created, each of them having a sequential filename ie "sourcefile_index.png" so that I can create a movie from them. Please could someone tell me where I am going wrong? the following code works fine and

I found this sentence in the Ogg format specs: http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-res.html "A residue vector may represent spectral lines, spectral magnitude, spectral phase or hybrids as mixed by channel coupling." But where does the spectral phase information come from ? AFAIK MDCT doesn't provide any phase information. And in OGG-encoding, MDCT is taking place a few

Dear R Community, I am currently student at the Vienna University of Technology writing my Diploma thesis on causality in time series and doing some analyses of time series in R. I have the following questions: (1) Is there a function in R to estimate the PARTIAL spectral coherence of a multivariate time series? If yes, how does this work? Is there an test in R if the partial spectral

Hi all, I am dealing with paleoceanographic data and I have a C14 time serie and one other variable. I would like to perform a spectral analysis (fft or wavelet) and plot it. Unfortunately I don't know the exact script to do this. Does anybody could send me an example to perform my spectral analysis ? I Thank you David Changez de tête et de tenue tous les jours si vous le voulez !