We come closer to a definitive answer on the relative merit of Ledoit-Wolf shrinkage versus a statistical factor model for variance matrices. Previously This post builds on the post entitled: A test of Ledoit-Wolf versus a factor model That post depended on some posts previous to it. New information Previously ... [Read more...]

Julien just signaled an intermitent disappearance of the posts on the ‘Og, depending on the operating system: Ubuntu 10.10 seems to be working (most of the time!) while Mac and Windows are having problems… This is beyond my abilities, I have contacted WordPress support, maybe they are working on some new ... [Read more...]

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Here are some useful extension to the "mtable" function in the memisc package. [Read more...]

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Over at R community site inside-R.org, Revolution's Joseph Rickert has published a How-To guide with tips for new users on How to Learn R, with links to resources for R books, blogs and courses. Check it out at the link below. Inside-R: How to Learn R [Read more...]

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I thought it would be fun to play around with the R package twitteR , an R API into Twitter.  I decided to take the most prominent news story of the past few days, Osama bin Laden’s death, to see … Continue reading → [Read more...]

This thread has been widely discussed on a lot of forums. To make a long story short, running natively R on an iDevice (meaning iPhone/iPad) is disabled by its OS, unless it is jailbroken. The steps for the installation through Cydia are described in this R wiki, or this ... [Read more...]

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I’m starting on my real R-Scripts now. We got an assesment for some Reports and they needed my graphs and Veerle’s Reports. So the tasks are: Well distribution plot Quality plate control Surface Plot Heatmap CirclePlot and more to come&#823... [Read more...]

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You may notice that I don’t have that many posts on my blog, and they are all about R. The paucity of my posts makes me a bit sad, but not much, really… What makes (or better, used to make me) sad is that posts of R code (used ... [Read more...]

My son would be extremely proud if I tell him I can spend hours building robots. Well, my robots are not as fancy as Dr Tenma's, but they usually do what I ask them to do. For instance, it is extremely simple to build a robot with R, to extract ... [Read more...]

I provide here an R function to estimate gene diversity of diallelic sites (e.g. SNPs), given allele frequencies at each segregating site. The function takes three input parameters: maf: a numeric value (or vector) representing minor allele frequency at each site. Default is 0.5 nreads: size of each resampling experiment. ... [Read more...]

In this post, I’m going to go over some basics of using conditionals and loops in R. I’ll expand on the example I use here in future posts. The conditionals and loops will be used to create some dummy eye movement data. Background Before I get into the ... [Read more...]

I recently decided to present a talk to the Denver R Users Group (DRUG) on how to make an R package (May 17). There were only two problems: (1) I’ve never made a package and (2) I had nothing in mind … Continue reading → [Read more...]

The March 2011 issue of JASA contains a review of Introducing Monte Carlo Methods with R by Hedibert Lopes. As in the previous review, the poor quality of the figures is (rightly) pointed out by Hedie. However, the main message of the review remains very positive and, furthermore, Hedie advertises the ‘... [Read more...]