similar to: R-squared in mixed-effects models

Hi everyone Can anyone tell me how I normalise a power spectral density (PSD) plot of a periodical time-series. At present I get the graphical output of spectrum VS frequency. What I want to acheive is period VS spectrum? Are these the same things but the x-axis scale needs transformed ? Any help would be greatly appreciated Tom

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

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

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

I've written a function that regularly throws the "cannot allocate vector of size X Kb" error, since it contains a loop that creates large numbers of big distance matrices. I'd be very grateful for any simple advice on how to reduce the memory demands of my function. Besides increasing memory.size to the maximum available, I've tried reducing my "dist" objects to 3

I'm looking for an R function that simply recodes a quantitative variable into a number of classes according to specified break-points. Obviously I can do this using nested ifelse() commands, but I want to write it into a function where I can't pre-specify the number of classes. Is there an obvious way to do this? An example to clarify: how to convert c(0,10,5,1,9,6) to

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:

Hi, I use rsync to back up my Linux system to hard drive. I use the -av option, and it preserves uids. However if I reinstall Linux, and try to restore from the backup hard drive, the owner permissions get all mixed up, I assume since the numeric uids don't match up with the equivalent usernames any more. For example, user nobody might have had uid 123 in my old system, but now in the new

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/

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

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

Dear R users, I'm trying to get a good x-scale and labels on a plot like the one below. library(lattice) ## make almost a year of hourly data: mydat <- data.frame(dates = Sys.time() + 3600 * (1:7000), y = runif(7000)) ## plot it xyplot(y ~ dates, data = mydat, type = "l") Only one x-label is given (May). I would prefer several because it makes the plot very difficult to

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 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, I have fitted a model using a glm() approach and using a gls() approach (but without correcting for spatially autocorrelated errors). I have noticed that although these models are the same (as they should be), the AIC value differs between glm() and gls(). Can anyone tell me why they differ? Thanks, Geertje ~~~~ Geertje van der Heijden PhD student Tropical Ecology School of Geography

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 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 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

Subject: nls, step factor 0.000488281 reduced below 'minFactor' of 0.000976563 Hi there, I'm trying to conduct nls regression using roughly the below code: nls1 <- nls(y ~ a*(1-exp(-b*x^c)), start=list(a=a1,b=b1,c=c1)) I checked my start values by plotting the relationship etc. but I kept getting an error message saying maximum iterations exceeded. I have tried changing these