Antoniak's 1974 article titled Mixtures of Dirichlet Processes with Applications to Bayesian Nonparametric Problems (Annals of Statistics 2(6):1152-1174) is a fundamental work for most modern developments in this area. The article gives two expressions for the expected number of distinct values in a sample of size n, drawn from a Dirichlet ... [Read more...]

Slow day at PSY headquarters: Click see wordleWe grabbed the Solvency II directive text from the EC website (© European Union, http://eur-lex.europa.eu/) and ran it through a couple of lines of R code to draw up wordcount frequencies. Then we plotted the text in Wordlehttp://www.wordle.net/... [Read more...]

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Hey, Since a new paper that I’ve co-written has appeared on arXiv, here is a quick post summarizing it. The paper is named: An Adaptive Interacting Wang-Landau Algorithm for Automatic Density Exploration and describes improvements over the Wang-Landau algorithm described … Continue reading → [Read more...]

I’ve just finished and uploaded another climate data package for R. This one focuses on  CRN the climate Reference Network Here is their home page   The package for now is really simple, but all of the packages  I’m building are getting simpler. In the end ( whenever that is ) ... [Read more...]

Following on from some of my earlier posts, this is purely about, hopefully, saving some other people some time in putting this together. Height z-scores are required to then calculate the blood pressure z-scores. The CDC (Center for Disease Control … Continue reading → [Read more...]

I've added facebook like button in the home page of the R Graph Gallery and on each image page, i.e. this one which I "like". [Read more...]

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I just released the first official version of the ‘intergraph’ R package. With the functions provided in the current version (1.1-0) you can convert network data objects between classes ‘igraph’ and ‘network’. The package supports directed and undirected networks, and handles the node, tie, and network (graph) attributes. Mutliplex networks (... [Read more...]

This seems like as good a day as any to review CrossValidated, and the whole StackExchange constellation of websites. It’s been a month since I joined, exactly, and today I also crossed the 1,000 reputation threshold on the site. So why not give my impressions of it? First, how I ... [Read more...]

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In cricket a player who can perform well with both the bat and bowl is a great asset for any team and across the history of international cricket there have been a number of cricketers that hall into this bracket. It is difficult to specify a set of criteria to ... [Read more...]

Julien Cornebise has [once again!] pointed out a recent Guardian article. It is about commercial publishers of academic journals, mainly Elsevier, Springer, and Wiley, with a clear stand from its title: “Academic publishers make Murdoch look like a socialist“! The valuable argument therein is that academic publishers make hefty profits (... [Read more...]

The R package rJava allows R to be accessed in Java programs. The part of the package that allows this is jri. The notes on the rJava site about getting jri to work didn’t help me much getting it to … Continue reading → [Read more...]

The next major release of R has been announced: R 2.14.0 is scheduled for October 31. Details are still coming in about the new features planned for this release, but R core member Luke Tierney has revealed some of the performance improvements expected, and R core member Brian Ripley has spoken of ... [Read more...]

One of the most crucial problems in HPC is that every error you make have much greater impact than in the normal computing — there is nothing more amusing than finding out that few-day simulation broke few minutes before the end because of an unfortunate value thrown by a random generator, ... [Read more...]

Like many users and producers of R packages, I have never had any formal training in computer science. I’ve come to to the conclusion that this is a serious omission in a professional researcher’s training. Computer scientists and professional hackers … Continue reading → [Read more...]

This package has been a long time in the making.  In the end it’s more of a data package than a functional package, but pulling all the pieces together required me to learn some really cool packages: raster ( which I already knew ) rgdal and RCurl.  I’ll provide a ... [Read more...]

Basically, DTW (dynamic time warping) is an algorithm to output cumulative distance of two time sequences, which is widely used e.g. for classification and clustering.For example, when using k-mean for clustering, we can use DTW as distance function. Here is one of such nice instances (using R: http://... [Read more...]

Yesterday I wanted to create a map of participants from a study on social media and partisan selective exposure that Sean Westwood and I ran recently, with participants from Amazon’s Mechanical Turk.  We recorded ip addresses for each Turker participant, so … Continue reading → [Read more...]