similar to: Code to fetch summary info from vector

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/

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 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

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, 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

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 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

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, 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'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

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

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

I'm wanting to create a series of near-identical matrices via the addition of "white noise" to my starting matrix. Is there a function within R which will allow me to do this? Thank you Laura Quinn Institute of Atmospheric Science School of Earth and Environment University of Leeds Leeds LS2 9JT tel: +44 113 343 1596 fax: +44 113 343 6716 mail: laura at env.leeds.ac.uk

Hi, Is there a neat way of working out the slope of a flat surface in R? Given (x,y,z) co-ordinates of the four corners of a square, is there a function which will allow me to calculate the "mean" slope of the surface in a given direction? Thanks in advance.. Laura Laura Quinn Institute of Atmospheric Science School of Earth and Environment University of Leeds Leeds LS2 9JT tel: +44

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, Is it possible to recreate "smoothed" data sets in R, by performing a PCA and then reconstructing a data set from say the first 2/3 EOFs? I've had a look in the help pages and don't seem to find anything relevant. Thanks in advance, Laura Laura Quinn Institute of Atmospheric Science School of Earth and Environment University of Leeds Leeds LS2 9JT tel: +44 113 343 1596

Hi, I am applying the following code to map pca loadings onto a 3d grid, my problem is this - the output only plots the spheres in the requested color (in this case "red") for the first argument. The sphere from the second argument appear as flat dark circles. Also the text3d() command only seems to work for a couple of the positions, with no text added in most cases. Could anyone offer