I recently decided to revisit some R code that implements a Gibbs sampler in an attempt to decrease the iteration time. My strategy was to implement the sampler state as an R environment rather than a list. The rationale was that passing an environment to and from functions would reduce the amount of duplication (memory
I’ve had enough of copy and pasting output from my R session into my email editor, blog, etc. I need something like Sweave for plain text files. In particular, I want the result of parsing <<echo=TRUE>>= f <- function(x) { x + 1 } f(1) @ with Sweave, but without the latex markup. For example,
I completed (some time ago) an initial version of a patch for R, version 2.11.1, that adds a POSIX tty connection. The patch is confirmed to compile and works on Mac OS X (thanks to Ashwin Bhat of Georgia Tech) and Debian GNU Linux. However, it should be portable to other POSIX compliant operating systems.
In studying R‘s connections source code, I’ve put together a series of notes about their workings. Rather than let the notes go where most of my notes go (I have no idea ), I decided to do some proofreading and make the notes available to others who might be interested. These notes should make the
I recently e-mailed David Smith of Revolution Analytics with a few questions about their relationship with the R-project, and how they handle R‘s source code. David mentioned, and I’m flattered that my email motivated an additional page on the Revolution website. Beyond this, I have no other relationship with the company. I’d like to thank
Andrew Gelman wrote today about some erroneous U.S. Governor approval ratings, noting that the ratings for Janet Napolitano sum to 108%. In fact most of these ratings do not sum to 100%. I prepared a clean CSV file of the ratings, making use of R‘s XML library and the readHTMLTable function. The ratings data file
I really like R‘s stem function, it creates a stem-and-leaf plot right in the R console, no fancy graphics devices required! In a recent R-help post, Ralf Bierig presented a very nice ASCII scatterplot representing two densities. Unfortunately, I don’t know of any R function that will generate this type of plot, but I will
The R function iconv converts between character string encodings, for example, from the locale dependent encoding to UTF-8: > iconv("foo", to="UTF-8") [1] "foo" However, R has long-running trouble with embedded null characters ('') in strings. Hence, if we try to convert to an encoding that permits embedded null characters, iconv will fail: > iconv("foo", to="UTF-16")
I recently posted the message below with regard to sampling from the truncated exponential distribution. I left out the derivation of the CDF (mostly because text math is ugly), so I’ve included it here. There is also a short JSS article about truncated distributions in R. This problem in particular may likely be found in
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
