similar to: [Fwd: Re: Block comments in R?]

Is there any function to write a XML structure, after it was read using xmlTreeParse? Ex: library(XML) x <- xmlTreeParse("Irpf2008/aplicacao/dados/12345678901/12345678901.xml") # write it... Alberto Monteiro PS: please, brazilians, don't be offended by my foul language!

How on Earth can I know what are the arguments of any of the functions of the tcl/tk package? I tried hard to find, using all search engines available, looking deep into keywords of R, python's tkinter and tcl/tk, but nowhere I found anything remotely similar to a help. For example, what are the possible arguments to tkgetOpenFile? I know that this works: library(tcltk) filename <-

Why this kind of assignment does not work? n <- 1 f <- ifelse(n == 1, sin, cos) f(pi) this must be rewritten as: n <- 1 f <- cos if (n == 1) f <- sin f(pi) [oops. 1.224606e-16 instead of zero. Damn floating point errors :-/] Alberto Monteiro

Is there any generic function that gets the "home" directory? This should return /home/<user> in Linux and x:/Documents and Settings/<user> (or whatever) in Windows XP. Another (unrelated) question: what is the _simplest_ way to read and write R variables to/from files such that they are stored in a human-readable but R-like form? For example, if (say), x is a vector

Is there a simple way to plot a histogram with colors? For example, suppose I generate random points in the N(2,1) distribution: x <- rnorm(100000, mean = 2, sd = 1) Now I would like to plot the histogram: hist(x) but I would like to show the bars with x < 0 in red, and the bars with x >= 0 in lightgreen. Is there any simple way to do it? I think I can do it in two steps:

This is just my curiousity working. Suppose I write: f1 <- function(x) x + 1 f2 <- function(x) 2 * f1(x) f2(10) # 22 f1 <- function(x) x - 1 f2(10) # 18 This is quite obvious. But is there any way to define f2 in such a way that we "freeze" the definition of f1? f1 <- function(x) x + 1 f2 <- function(x) # put something here 2 * f1(x) # probably put something else here

I have a conceptual problem (sort of). Maybe there's a simple solution, maybe not. First, let me explain the test case that goes ok. Let x be a (fixed) n-dimensional vector. I simulate a lot of linear models, y = m x + c + error, then I do a lot of regressions. As expected, the estimated values of m (let's call them m.bar) are distributed according to a Student's t distribution.

Suppose that I have a matrix like: m <- rbind(c(1,2,3,4), c(2,3,2,1)) Is there any way to efficiently plot the _lines_ as if I was doing: plot(m[1,], type="l") points(m[2,], type="l", col="red") (of course, in the "real world" there much more than just 2 lines and 4 columns...) Alberto Monteiro

I mean, I can generate a expression, for example, with: z <- expression(x+y) But then how can I _use_ it? Is it possible to retrieve information from it, for example, that z is a sum, its first argument is x (or expression(x)) and its second argument is y? Alberto Monteiro

I want to make a plot, but instead of showing _numerical_ values, I would like to show _symbolic_ values. For example, I want to plot a function y = a x + b, where x varies between Xmin and Xmax. I would like the plot to show, in the x-axis, the strings Xmin and Xmax, instead of their numeric values. Is it possible? Alberto Monteiro

Dear R-experts, It is a quite stupid question but please help me. I am very confuced. I am able to import normal txt ant mat-files to R but unable to import .xls-file I do not understand the online help. Can please anyone send me the corresponding command lines? The .xls-file is attached. In my file we use commas for the decimal format (example: 0,712), changes might be needed. Thanks, Corinna

Is there any way to give a "decent" title after I plot something generated by decompose? For example: # generate something with period 12 x <- rnorm(600) + sin(2 * pi * (1:600) / 12) # transform to a monthy time series y <- ts(x, frequency=12, start=c(1950,1)) # decompose z <- decompose(y) # plot plot(z) Now, the title is the ugly "Decomposition of additive time

Hi everyone, I am interested in estimating this type of random effects panel: y_it = x'_it * beta + u_it + e_it u_it = rho * u_it-1 + d_it rho belongs to (-1, 1) where: u and e are independent and normally zero-mean distributed. d is also independently normally zero-mean distributed. So, I want random effects for group i to be correlated in t, following an AR(1) process. I am

Is there any way that I can do something like this: png("file.png", width=200, height=200) polygon(c(50, 50, 150, 150), c(50, 150, 150, 50)) dev.off() and then have a png file with a 100 x 100 pixels rectangle in the middle of it? It seems that when I call "plot", it redefines the image coordinates to some "optimized" value and then I lose any information to

As a big fan of Wikipedia, it's frustrating to see how little there is about R in the correlated project, the Wikibooks: http://en.wikibooks.org/wiki/R_Programming Alberto Monteiro

Is there any way to write an imagematrix generated by the rimage package? Reproducible example: library(rimage) x <- read.jpeg(system.file("data", "cat.jpg", package="rimage")) png("newcat.png") plot(x) dev.off() The newcat.png image is different from the original file, because there are ugly white borders around it. Alberto Monteiro

This is probably very trivial - so I can't find an answer in the help files. When I have a series x (x[1], x[2], ... x[n]) and I want to construct a new series y (y[1], y[2], ... y[m]) such that y's are either interpolations of the x's (when m > n) or a weighted mean (when m < n), is there any direct function to do it? For example, passing from 3 to 4 would be the same as

I need arguments pro-S-PLUS and against SAS for a meeting I will have next week. S-Plus is (90 - 99)% compatible with R, so using S-Plus will make things much easier for everyone. But I can't use this argument. What other arguments could I use? Alberto Monteiro

hi dear R users, I'm a newbie with R and excuse me if my question is stupid ... but i've read lot of documentation and I don't know how to do. I have a dataset like x y var1 var2 2 4 10 50 3 3 20 70 3 2 50 68 4 5 34 42 5 3 10 23 7 8 23 42 7 3 23 34 [...] And I need to produce grids like : y\x ]0-2] ]2-4]

I am writing a package which uses the Rgraphviz package which in turn uses the graph package, but my question does not (I believe) pertain specifically to the these packages so therefore I dare to post the question here: I my package I have a function "edges" which works on some graphs I have defined. However, there is also a function "edges" (or rather a generic method) in