The last couple of days I read a number of times about stabilization in house prices which had been dropping due to the crisis. And you get hit by numbers such as change against Q2 2013 or Q3 2012. These are accompanied by reasons why this or that quarter may be special ... [Read more...]

I’ve written a few posts now about using parallel tempering to sample from complicated multi-modal target distributions but there are also other benefits and uses to this algorithm. There is a nice post on Darren Wilkinson’s blog about using tempered posteriors for marginal likelihood calculations. There is also ... [Read more...]

I’ve recently wanted to geocode a large number of addresses (think circa 60k) in Ireland as part of a visualisation of the Irish property market. Geocoding can be simply achieved in R using the geocode() function from the ggmap library. The geocode function uses Googles Geocoding API to turn ... [Read more...]

I have a standard code for ggplot2 which I use to make line graphs, scatter plots, and histograms. For lines or scatters: p [Read more...]

A good news is that the elliplot 1.1.1 is listed at CRAN. Now the procedure to install is simple for Windows users. install.packages('elliplot') library(elliplot) ellipseplot(1:9) The above is the simplest … Continue reading → [Read more...]

In case you missed them, here are some articles from September of particular interest to R users: Todd Schneider wrote an algorithm in R to find the "most concave" US state (it's NY), and created an animation to show how it works. Rob Hyndman (of the "forecast" package) describes how ... [Read more...]

October 24, 2013 - 18:00 - 21:00 Fiori Oscuri Bistrot & Bar (www.fiorioscuri.it) Via Fiori Oscuri, 3 - Milano (Zona Brera) 18.00 - 18.15 Registration 18.15 - 18.45 Welcome presentation R and Microsoft Office Nicola Sturaro, Consultant at Quantide 18.45 - … Continue reading → [Read more...]

The Bayesian 2PL IRT model we defined in Post 1 set a hyper-prior on the variance of the person ability parameters. This post implements the sampler for this parameter as a Gibbs step. We will check that Gibbs step is … Continue reading → [Read more...]

In this post, we will build the samplers for the item parameters using the generic functions developed in Post 5 and Post 6. We will check that the samplers work by running them on the fake data from Post 2, … Continue reading → [Read more...]

At Google, building, managing and safely securing some of the world’s largest storage systems requires complex analysis of filesystem metadata. This is an important part of making sure that the information stored within those systems is quickly accessible and always secure. We're always looking for ways to make our ... [Read more...]

Rick Wicklin on the SAS blog made a post today on how to tell if a sequence of coin flips were random.  I figured it was only fair to port the SAS IML code over to R.  Just like Rick Wicklin did in his example this is the Wald-Wolfowitz test ... [Read more...]

In this post we refactor the proposal function from the previous post into a generic normal proposal function. This allows us to implement normal proposals for the (yet to be developed) samplers for the item parameters without duplicating code. Our … Continue reading → [Read more...]

A best practice in software engineering is to re-use code instead of duplicating it. One reason for this is that it makes finding and fixing bugs easier. You only have to find the bug once instead of finding it every … Continue reading → [Read more...]

This particular custom legend was designed with three purposes: To effectively bin values based on a theoretical minimum and maximum value for that variable (e.g. -1 and 1 or 0 and 100) To use a different interval notation than the default To handle NA values Even though this particular legend was designed ... [Read more...]

Dear morphometricians,Geomorph 1.1-4 has been recently uploaded to CRAN. Please update your R package list or go here to download the latest version. The news section highlights the following changes: CHANGES IN GEOMORPH VERSION 1.1-4NEW FEATURES o ... [Read more...]

The Area Under the Receiver Operator Curve is a commonly used metric of model performance in machine learning and many other binary classification/prediction problems. The idea is to generate a threshold independent measure of how well a model is able to distinguish between two possible outcomes. Threshold independent here ... [Read more...]

I have just published a new version of solaR and rasterVis on CRAN. From now on both packages will be …Continuar leyendo » [Read more...]

The V Conference of R Users  (Zaragoza, 12-13 December 2013) will include the 2nd Data Analysis Contest Using R sponsored …Continuar leyendo » [Read more...]

I had someone ask me the other day how to take a scatterplot and draw something other than a straight line through the graph using Excel.  Yes, it can be done in Excel and it’s really quite simple, but there are some limitations when using the stock Excel dialog ... [Read more...]

Previously, I came up with a solution to R's less than ideal handling of named capture in regular expressions with my re.capture() function. A little more than a year later, the problem is rearing its ugly - albeit subtly different - head again. I now... [Read more...]