***This tutorial has been updated, please click here*** I frequently use R (a free software environment for statistical computing and graphics) for data analysis. As almost all my data are spatial it is often good to produce a map of the results without having to export the data into another GIS package. I am often
Yesterday, Deepak wrote about BridgeDB, a software package to deal with the “identifier mapping problem”. Put simply, biologists can name a biological entity in any way that they like, leading to multiple names for the same object. Easily solved, you might think, by choosing one identifier and sticking to it, but that’s apparently way too 
My last post provided examples of how to use the LSPM package. Those who experimented with the code have probably found that constrained optimizations with horizons > 6 have long run-times (when calc.max >= horizon).This post will illustrate how the s...
Out of curiosity, I produced a “sequential” set of ideal point estimate for the (current) 111th U.S. Senate, plotting the results in the graph attached below (click on the thumbnail); as is conventional, red is Republican and blue is Democratic. The analysis uses all 373 non-unanimous roll calls in the 111th Senate thus far. Each
There's been a number of earthquakes in the Solomon Islands over the past few days, including one that caused a tsunami to partially destroy the village of Baniata on Rendova, Western Provence. You can see exactly how many earthquakes have occurred the...
There's been a number of earthquakes in the Solomon Islands over the past few days, including one that caused a tsunami to partially destroy the village of Baniata on Rendova, Western Provence. You can see exactly how many earthquakes have occurred the...
My apologies for the long break between posts. Before the end of this week I’ll return to my series of posts on image processing in R. In the intervening time, I’ve finished a piece of code that I’d like to officially release to the public. The code in question is a very minimal object-relational mapper
FriendFeed is a social media service, where groups of people can post interesting information from the Web, and "like" or comment posts from others. Statistical Bioinformatician Neil Saunders is a member of the "Life Scientists" group, and has posted an analysis of the group's activity in 2009 to his blog. He used Ruby and the FriendFeed API to extract...
I have received several requests for additional LSPM documentation over the past couple days and a couple months ago I promised an introduction to LSPM. In this long-overdue post, I will show how to optimize a Leverage Space Portfolio with the LSPM pa...
The R statistical computing environment is awesome, but weird. How to do database operations in R is a common source of questions. The other day I was looking for an equivalent to SQL group by for R data frames. You need this to compute summary statist...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
