REvolution Computing is a sponsor of the Bay Area R User Group, which gathered on Tuesday for its monthly meeting. This month's meeting was in a cozy setting at San Jose State University, and was hosted by David Czerwinski who teaches data mining there. The topic at hand was search, ... [Read more...]

One of R's biggest strengths is its unparalleled graphing capabilities.  Just see any of our previous posts on ggplot2, visualization, or other posts tagged with R. R has several fundamentally different systems for plotting, including base graphics, lattice, and ggplot2.  Furthermore, many add-on packages come with their own functions for ... [Read more...]

An important aspect of regression involves assessing the tenability of the assumptions upon which its analyses are based. This tutorial will explore how R can help one scrutinize the regression assumptions of a model via its residuals plot, normality h... [Read more...]

With a little guidance from the indefatigable Hadley Wickham, I figured out today how to implement the setter methods that were missing from my example user class. To review, let’s rebuild the getter methods for my user object: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 [...] [Read more...]

The New York Times last weekend looked at the controversy around the recent changes to the mammogram guidelines from a mathematical perspective. Compared to the analysis based on Bayes' Theorem from the Harvard Social Science Statistics blog (which apparently caused some controversy itself: that post was deleted and later replaced ... [Read more...]

The grammar of graphics approach to constructing graphs has been implemented in the ggplot2 package in R. The author of the package, Hadley Wickham, has provided a website with many details of using the system to create nice looking graphics. The package removes many of the awkward parts of setting ... [Read more...]

The latest update to R, R 2.10.1, is now available for download in source form from your local CRAN mirror. Binary versions (for Mac, Windows, and Linux) will become available over the next few days. As a maintenance release, this update focuses on minor changes and bug fixes. The complete list ... [Read more...]

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A new version of RQuantLib is now out at CRAN and in Debian. It updates the package to the 0.9.9 release of QuantLib and is mostly a maintenance release with a few minor fixes along the way. Full changelog details, examples and more details abo... [Read more...]

Andrej Blejec has a very nice R demo of Galton's quincunx (link1, link2). It is a bit tedious to copy the code from PDF to R console, but it is worth the effort as the demo simulation clearly shows the nature of quincunx. After a bit of search I also ... [Read more...]

IowaHawk has a excellent article attempting to reproduce the infamous CRU climate graph using OpenOffice: Fables of the Reconstruction. We thought we would show how to produced similarly bad results using R. If the re-constructed technique is close to what was originally done then so many bad moves were taken ... [Read more...]

Until recently, I’ve never had any reason to learn how to define my own classes in R. Having learned this week, I was surprised to find out how easy it is to start implementing classes in R. If you know nothing about creating classes and class methods in R, ... [Read more...]

Probably all of us have met the issue of handling missing data, from the basic portfolio correlation matrix estimation, to advanced multiple factor analysis, how to impute missing data remains a hot topic. Missing data are unavoidable, and more encompassing than the ubiquitous association of the term, irgoring missing data ... [Read more...]

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A bar graph is a frequently used type of display that compares counts, frequencies, totals or other summary measures for a series of categories, e.g. sales in different market sectors or in quarters in a financial year. The bar graph can be laid out with the categories either on ... [Read more...]

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I've pushed to CRAN the package bibtex package The package defines the read.bib function that reads a file in the bibtex format. The code is based on bibparse The read.bib function generates an object of class citationList, just like utils::citation [Read more...]

It’s common knowledge that I struggle wrapping my head around the apply functions in R. That is illustrated very clearly in the following discussion on Stack Overflow: Dirk’s comment is actually spot on. I’ve asked the same damn question at least 4-5 times. Only I didn’t ... [Read more...]

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Let’s say that you’re fitting a cumbersome model so time is not to waste over a PC staring at the screen half anxious-half bored… Then, you can always leave and go on with meetings and all your daily routine and have R notify you the results! How? We ... [Read more...]