Locally weighted scatterplot smoothing (LOWESS) or local regression (LOESS) is widely used to highlight “signal” in variables from stratigraphic sequences. It is a user-friendly way of fitting a local model that derives its form from the data themselves rather than having to be specified a priori by the user. There ... [Read more...]

Earlier today, a minor update / maintenance release of RcppGSL---our interface package between R and the GNU GSL using our Rcpp package for seamless R and C++ integration---arrived on on CRAN. It contains a number of minor changes to accomodate chan... [Read more...]

The RHadoop project continues the Big Data integration of R and Hadoop, with a new update to its rmr package. Version 1.3 of rmr improves the performance of map-reduce jobs for Hadoop written in R. New features include: An optional vectorized API for efficient R programming when dealing with small records. ... [Read more...]

Since rApache 1.1.15 you’ve been able to deploy you Rook applications like so:

# Run the Rook application named 'app'. On each request, the expression 
# 'Rook::Server$call(app)' is evaluated in an environment populated by
# rookapp.R. 'app' is expected to be found in that environment.
<Location /test/RookApp>
        SetHandler r-handler
        RFileEval /path/to/Rook/App/rookapp.R:Rook::Server$call(app)
</Location>

Let’s go through the above example step by step, starting with the Location directive from apache. The Location Directive Works on URLs In apache, the Location directive works on the URL space of the server. ... [Read more...]

I took part in the second Data Science London Hackathon last weekend (also my second hackathon) and it was a very different experience compared to the first hackathon. Once again Carlos and his team really looked after us. The data was released 24 hours before the competition started and even though ... [Read more...]

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Estimating required hospital bed capacity requires a thorough analysis. There are a lot of ways of approaching a capacity requirement problem, but I think we can agree that a simple spreadsheet analysis just won't cut it. The approach described in this post makes use of discrete-event simulation and, just ... [Read more...]

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One of the shortcomings of regression (both linear and logistic) is that it doesn’t handle categorical variables with a very large number of possible values (for example, postal codes). You can get around this, of course, by going to another modeling technique, such as Naive Bayes; however, you lose ... [Read more...]

Capturing the dependence between explanatory variables in the posterior distribution while implementing a Bayesian analysis is crucial. Taking such a dependence into account reveals the sensitivity of posterior distributions of parameters to depen... [Read more...]

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Mirai Solutions GmbH (http://www.mirai-solutions.com) is very pleased to announce the release of XLConnect 0.2-0, which can be found at CRAN. As one of the updates, XLConnect has moved to the newest release of Apache POI: 3.8. Also, the lazy evaluation … Continue reading → [Read more...]

I have tested several R optimization functions before: nlm, optim(Nelder-Mead), optim(BFGS), optim(SANN), nlminb, optim (L-BFGS-B) for a eight-parameter Vasicek interest rate model, overall I find that for my setting, nlminb is the best and all R func... [Read more...]

I provide links to two (free, publicly available) graduate level political methodology classes by Justin Esarey (Rice University) and Gary King (Harvard University). Both classes focus on statistical theory and modeling in R. [Read more...]

A simple portfolio optimization problem is used to look at several R functions that use randomness in various ways to do optimization. Orientation Some optimization problems are really hard. In these cases sometimes the best approach is to use randomness to get an approximate answer. Once you decide to go ... [Read more...]

When I attended usrR! 2012 last month, there was an interesting presentation by Dr. David Kahle about the package ggmap. It is a package built over ggmap2 and helps us map spatial data over online maps like Google maps or Open Street Maps. I decided to give ggmap package a try ... [Read more...]

The LDS_TOOLS package for R has been replaced by the new eeptools package. I am renaming the package for a number of reasons. First, LDS is a technical industry term in education that stands for Longitudinal Data Systems, which is not commonly known an... [Read more...]

In our previous statistics tutorials, we have treated population parameters as fixed values, and provided point estimates and confidence intervals for them. An alternative approach is the Bayesian statistics. It treats population parameters as random... [Read more...]

I’ve only recently begun working from an evolutionary perspective, and I can’t imagine why I haven’t thought about it much before. After all, it comes up in just about everything that we do in ecology. For example, I’m currently feeding … Continue reading → [Read more...]

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