similar to: Loops and dataframes

Hi, I can not comprehend the linear fitting results of polynoms. For example, given the following data (representing y = x^2): > x <- 1:3 > y <- c(1, 4, 9) performing a linear fit > f <- lm(y ~ poly(x, 2)) gives weird coefficients: > coefficients(f) (Intercept) poly(x, 2)1 poly(x, 2)2 4.6666667 5.6568542 0.8164966 However the fitted() result makes sense: >

Hi, my client pc hangs on pxelinux before starting to fetch the linux kernel. It hangs after printing the ip information row. No traffic is observed at this point on the network. The pxelinux is transferred to the client through a tftp server and with no problems. What options do I have to proceed from this point and try to find out where the problem is? Thanks, Firas. -- Firas Swidan, PhD

Hi, I am having difficulties in finding ways to analyse scatter plots and quantitatively differentiate between them. Since this is best demonstrated by a figure, I have attached one with 4 subfigures (a)-(d). Qualitatively (and I hope you would agree with me), sub-figures (a), (b), and (d) seem to represent uniform 2d scatters. It is hard for me to quantify it, but it seems as if the envelopes

Hi, R is having the following weird behavior and I am not sure if that is a feature or a bug: I am working on the following "3D" array: > bIm , , 1 [,1] [1,] TRUE [2,] TRUE [3,] TRUE [4,] TRUE [5,] TRUE > class(bIm) [1] "array" > dim(bIm) [1] 5 1 1 When I try to get the first 2D subarray, the whole thing folds into a vector: > bIm[,,1] [1] TRUE TRUE TRUE

Hi, I have collected a bunch of old PII PCs that I am trying to PXE boot. There NICs are old and so I use etherboot floppy to emulate a native PXE boot. I have configured tftp, dhcpd, pxelinux, and all the other stuff. Everything works fine till pxelinux start booting. Then it stucks after printing the IP row. --------------- pxelinux output ----------------------- PXELINUX 3.10 2005-08-24

Hi, I have a small R question: how to print a single "\" character? I have the following results: > print("\") does not work > print("\\") [1] "\\" I need to make the following substitution as well, but it does not work either: > sub("_","\_","g_g") [1] "g_g" Thanks in advance, Firas.

Hi, I am using the following command to print to a file (I omitted the file details): cat( paste( paste(orientation, start, end, names,"\n"), paste(start, end, "exon\n"), sep="")) where "orientation" and "names" are character vectors and "start" and "end" are integer vectors. The problem is that R coerce the integer vectors

Hi, I am having a problem with a very slow indexing and sub-sectioning of a 3d array: > dim(arr) [1] 245 175 150 For each point in the array, I am trying to calculate the mean of the values in its surrounding: mean( arr[ (i - radius):(i + radius), (j - radius):(j + radius), (k - radius):(k + radius)] ) Putting that code in 3

Hi, I was wondering if anyone is aware of an R interface to ImageMagick (www.imagemagick.org)? Since R does not support a lot of image processing functions, having such an interface could be very useful. Alternatively, ImageMagick has a couple of different interfaces (including to C and C++). I was wondering if one can use these to call ImageMagick functions from R. I am posting a similar

Hi, I have two (different types of) measurements, say X and Y, resulting from the same set of experiments. So X and Y are paired: (x_1, y_1), (x_2, y_2), ... I am trying to calculate the standard deviation of Y with respect to X. In other words, in terms of the scatter plot of X and Y, I would like to divide it into bins along the X-axis and for each bin calculate the standard deviation along

Dear Rdevelopers The background for this email is that I was helping a PhD student to improve the speed of her R code. I suggested to replace calls like t(AA)%*% BB by crossprod(AA,BB) since I expected this to be faster. The surprising result to me was that this change actually made her code slower. > ## Examples : > > AA <- matrix(rnorm(3000*1000),3000,1000) > BB <-

Hello, The problem I'm working now requires to operate on big matrices. I've noticed that there are some packages that allows to run some commands in parallel. I've tried snow and NetWorkSpaces, without much success (they are far more slower that the normal functions) My problem is very simple, it doesn't require any communication between parallel tasks; only that it divides

Hi, I have a 5x731 array A, and I want to compute the sums of the columns. Currently I do: apply(A, 2, sum) But it turns out, this is slow: 70% of my CPU time is spent here, even though there are many complicated steps in my computation. Is there a faster way? Thanks, Martin

Hi, Couldn't is.unsorted() bail out immediately here (after comparing the first 2 elements): > x <- 20000000:1 > system.time(is.unsorted(x), gcFirst=TRUE) user system elapsed 0.084 0.040 0.124 > x <- 200000000:1 > system.time(is.unsorted(x), gcFirst=TRUE) user system elapsed 0.772 0.440 1.214 Thanks! H.

hi all If I wanna get the total number of lines in a big file without reading the file's content into R as matrix or data frame, any methods or functions? thanks in advance. Regards

Dear I hope you are wery well when read this e-mail.My name is Firas ALSHAWY and I am a Phd student in the high Institute of marine research - tishreen university- Syria I would like to want some help my in my research, I have data ( length - weight - gonad weight - fishing mortality - natural mortality - the number of fish-temperature of water, maximum age ) , I would like to use the package (

Hi, I was trying to evaluate the pearson correlation and the p-values for an nxm matrix, where each row represents a vector. One way to do it would be to iterate through each row, and find its correlation value( and the p-value) with respect to the other rows. Is there some function by which I can use the matrix as input? Ideally, the output would be an nxn matrix, containing the p-values

What is the difference between the above two operations ? [[alternative HTML version deleted]]

Hello, is it possible to create my own connection which I could use with read.table or scan ? I would like to create a connection that would read from multiple files in sequence (like if they were concatenated), possibly with an option to skip first n lines of each file. I would like to avoid using platform specific scripts for that... (currently I invoke "/bin/cat" from R to create a

Hi all, I am a new R- user and I am going through the R-manuals, but I could not find an answer for my question. I am confused about when to use the GAM package and when to use the MGCV package?? My Model is a GAM model of continuous outcome and many non-linear continuous predictors (using the "s" function) as well as categorical predictors. Thanks in advance for your help and