similar to: question on function arguments

DeaR list, I happily use eigen() to compute the eigenvalues and eigenvectors of a fairly large matrix (200x200, say), but it seems over-killed as its rank is limited to typically 2 or 3. I sort of remember being taught that numerical techniques can find iteratively decreasing eigenvalues and corresponding orthogonal eigenvectors, which would provide a nice alternative (once I have the

Dear R list, I'm having difficulties in choosing between a list or a data.frame, or an array for the storage and manipulation of my data (example follows). I've been using the three for different purposes but I would rather like to know which is more adapted to what task. Here is the data I'm currently working on: 200 observations, each observation being a vector of length

Dear R helpers, I'm trying to write a numerical scheme for a boundary integral method to solve an electromagnetic problem. This requires the computation of the distance between points at the surface of an object (a sphere, in my example). Here is my code, > require(rgl) > r<-1 > size<-10 > theta<-seq(0,2*pi,length=size*2) > phi<-seq(0,pi,length=size) > pc

Dear all, The following example code produces a graph with ggplot2, to which I add several vertical lines of arbitrary colors. I am not satisfied with the legend: it automatically adds some vertical lines which I'd rather not see (they confuse the reader rather than add information in this case). > library(ggplot2) > dfr <- data.frame(values = sin(1:50/10), > fact =

Hello R list, I have two matrices of identical dimensions, and I want to fit a straight line for each pair of columns and plot the resulting lines. I got it to work with a for loop, but there must be a better way, > n<-5 > N<-10 > > data.x<-matrix(1:(n*N),ncol=n) > data.y<-matrix(1:(n*N) + rnorm(n*N,sd=1),ncol=n) > >

Hi, I need to create a text file in the following format, > 1 100.0 0 > 0 0 > 1 1 > 0 0 > 1 1 > # > 1 100.0 0 > 0 0 > 0 1 > 1 0 > 1 1 ... where # is part of the format and not a R comment. Each block (delimited by #) consists of a first line with three values, call it dose, and a list of (x,y) coordinates which are a matrix or data.frame, >

Dear list useRs, I have to generate a random set of coordinates (x,y) in [-1 ; 1]^2 for say, N points. At each of these points is drawn a circle (later on, an ellipse) of random size, as in: > N <- 100 > > positions <- matrix(rnorm(2 * N, mean = 0 , sd= 0.5), nrow=N) > sizes<-rnorm(N, mean = 0 , sd= 1) > plot(positions,type="p",cex=sizes) My problem is to

Hi, I've started my own (first) package, part of which consists in listing common physical constants (Planck's constant, the speed of light in vacuum, etc). I'm wondering what would be a good way of dealing with pairs of value/unit. > constants <- list( cel = 2.99792458e8 , #m/s > Z0 = 376.730313461, #ohm > eps0 = 8.854187817e-12,#F/m > mu0 = 4*pi*1e-7,#N/A^2

Dear R users, I'm porting a piece of Matlab code to R, but I'm now stuck with the following: I need an equivalent of besselJ(x, nu) that can handle a complex argument x. I couldn't find any R implementation. I did find a possible fortran solution in SLATEC (< http://www.netlib.org/slatec/ > , CBESJ-C), however I've never tried to use external C or Fortran code

Dear R users, I'm porting a piece of Matlab code to R, but I'm now stuck with the following: I need an equivalent of besselJ(x, nu) that can handle a complex argument x. I couldn't find any R implementation. I did find a possible fortran solution in SLATEC (< http://www.netlib.org/slatec/ > , CBESJ-C), however I've never tried to use external C or Fortran code

DeaR list, I'm running an external program that computes some electromagnetic response of a scattering body. The numerical scheme is based on a discretization with a characteristic mesh size "y". The smaller y is, the better the result (but obviously the computation will take longer). A convergence study showed the error between the computed values and the exact solution

DeaR list, Pardon the stupidity of this question but I've been trying this for a while now without success. I've followed the example given in the green book "programming with data", and I now have a working example of a S4 class with a few methods (plot, summary, as.data.frame). It's all very nice in one file, but I cannot find the way to put this information in a

DeaR list, I'm a bit lost in the behavior of substitute and co. I often use fairly long axis labels in my graphs (long to write, that is). Typically, they would contain some greek letters and units with exponents, as in: > xlab=expression(paste("text ", alpha, " / ", V,".", m^{-3}, ".", > kg^{-2}, ".", l^{4})) To make this a

Dear all, Trying to extract a few rows for each element of a list of data.frames, I'm puzzled by the following behaviour, > d <- lapply(1:4, function(i) data.frame(x=rnorm(5), y=rnorm(5))) > str(d) > > lapply(d, "[", i= c(1)) # fine, this extracts the first columns > lapply(d, "[", j= c(1, 3)) # doesn't do nothing ?! > > library(plyr)

Dear all, Trying to extract a few rows for each element of a list of data.frames, I'm puzzled by the following behaviour, > d <- lapply(1:4, function(i) data.frame(x=rnorm(5), y=rnorm(5))) > str(d) > > lapply(d, "[", i= c(1)) # fine, this extracts the first columns > lapply(d, "[", j= c(1, 3)) # doesn't do nothing ?! > > library(plyr)

DeaR list, Has anyone tried to mix the Sweave paradigm with the Markdown[*] (and co.) syntax? Would this be hard to implement? My tiny understanding of Sweave is that one can define new drivers for the text part, while some functions that deal with the R code would not require any modification. Here's the reason I'm interested in Mardown for a driver. I've been orbiting

Dear all, Happy new year! I posted a very similar question a few days ago, but probably too cluttered. Here is a tidy, minimal version: I want to make a package, with a data.frame d and a function f given below. Now, the function f needs to use the data.frame d. I could (and that's what I've done temporarily) make a local duplicate of this data.frame in the function definition,

Dear all, I'm writing a code that requires Bessel functions with complex argument. Searching the list, I found the continuation of a thread I initiated a few months ago: http://tolstoy.newcastle.edu.au/R/e4/devel/08/03/0746.html As I understand, the most promising option would be to use the fortran or C implementation of Amos,

Dear list, I have the following example, from which I am hoping to retrieve numeric values of the factor levels (that is, without the brackets): > > x <- seq(1, 15, length=100) > y <- sin(x) > > my.cuts <- cut(which(abs(y) < 1e-1), 3) > levels(my.cuts) hist() does not suit me for this, as it does not necessarily respect the number of breaks. getAnywhere

Dear List, I'm stuck on what seems like a simple indexing problem, I'd be very grateful to anyone willing to help me out. I queried a dataframe which returns a character vector called "plot". I have another dataframe from which I want to subset or select only those rows that match "plot". I've tried subset, and also the "which" command. plot