I came to R from SQL. I’ve heard that packages such as reshape and plyr are quite beautiful, but to me they are somewhat non-intuitive. I’m always looking for SELECT mean(sodium) as mean, variance(sodium) as var FROM texas GROUP BY … Continue reading → [Read more...]

Hadley Wickham has just released updates to his data-manipulation packages for R, plyr and reshape (now called reshape2), that are much faster and more memory-efficient than the previous incarnations. The reshape2 package lets you flexibly restructure and aggregate data using just three functions (melt, acast and dcast), whereas the plyr ... [Read more...]

Cyrus writes: I [Cyrus] was teaching a class on multilevel modeling, and we were playing around with different method to fit a random effects logit model with 2 random intercepts---one corresponding to "family" and another corresponding to "co... [Read more...]

I requested an academic copy of the Revolution R Enterprise today. Since they only have Windows or Redhat version, I installed it on an old spare machine dual-booting Linux and Windows. I like what they did with the IDE (the debugger is nice) and ... [Read more...]

Today I am travelling from Paris to Banff, via Amsterdam and Calgary, to take part in the Hierarchical Bayesian Methods in Ecology two day workshop organised at BIRS by Devin Goodsman (University of Alberta),  François Teste (University of Alberta), and myself. I am very excited both by the opportunity ... [Read more...]

At the ASA Statistical Computing Award ceremony in Vancouver last month, R's co-creator Ross Ihaka said that R began as a "system that was functional and well-designed, and made it easy and fun for other people to help". R's other co-creator, Robert Gentleman, also described the ability of others to ... [Read more...]

I’m starting to get familiar with ggplot2, and I really like it. I just found a very quick way to use several dataframes within the same plot, provided that the dataframes share columns names. One obvious application is the production (…)Read the rest of this entry » [Read more...]

David Winsemius discusses the analysis of the NHANES data set to create models that better predict Hepatitis C infection. [Read more...]

Sean Goggins presents a network analysis of MyLyn software development project. [Read more...]

Gilles Guillot from Technical University of Denmark taught a course based on our R book and he pointed out to me several typos in Chapter 5 of “Introducing Monte Carlo Methods with R”: p.137 second equation from bottom should be [right, another victim of cut-and-paste] p. 138  Example 5.7 denominator in the gradient ... [Read more...]

Some thoughts from Christian, including this bit: We need to consider separately 1. R's brilliant library 2. R's not-so-brilliant language and/or interpreter. I don't know that R's library is so brilliant as all that--if necessary, I don't thi... [Read more...]

In 2 weeks, on Wednesday September 22, I'll be hosting a webinar in conjunction with Andrew Lampitt at Jaspersoft. This new webinar is all about how to Deploy R: in other words, how to use the new server-based capabilities of Revolution R Enterprise 4 for Linux to embed the results of R scripts ... [Read more...]

In an earlier post, I described some ECG signal processing. In fact, these recordings were from my own heart, and I had collected them using a homemade ECG. The following is a repost from my old site describing the device. I assembled an instrumentation amplifier to measure cardiac potentials (i.... [Read more...]

There is no question that computer languages have helped pushed the envelope for applied mathematics.  It is hard to imagine where we would be without airline scheduling, supply chain management, or inventory control if it were not for all of the ... [Read more...]

Background: A common function in standard GIS software enables users to create a raster surface and extract values or clip it based on a set of polygons. This may be used in cases where you want analysis to be constrained to within a town’s boundaries or a coastline. This ... [Read more...]

As more people keep following the GeoNet website, they are starting to notice the seismic activity in areas other than Christchurch. A few people I've talked to have expressed concern that the Saturday 7-pointer has sparked earthquakes around the count... [Read more...]

Julien Cornebise posted a rather detailed set of comments (from Jasper!) that I thought was interesting and thought-provoking enough (!) to promote to a guest post. Here it is , then, to keep the debate rolling (with my only censoring being the removal of smileys!). (Please keep in mind that I do ... [Read more...]

Christian Robert, whose blog I commented-on here once before, had followed up on a recent set of posts by Radford Neal which had appeared both on Radford's blog and on the r-devel mailing list. Now, let me prefix this by saying that I really enjoyed Radford's posts. He obviously put ... [Read more...]

As announced by David Smith over at Revolution Analytics,  a ggplot2 Case Study Competition is on...   Rather than blogging for the last few days, I cobbled together an entry.  It is not a particularly mind bending use of ... [Read more...]

I picked up the AT&T Laboratories Cambridge database of faces for a clustering application. The database consists of images of 40 distinct subjects, each in 10 different facial positions and expressions. Typically, the goal of clustering in these data is to recover the ‘true’ partition, or that which isolates images of ... [Read more...]