Separation of degrees

January 20, 2012 | civilstat

Scientific American has a short article on trends in undergraduate degrees over the past 20 years, illustrated with a great infographic by Nathan Yau. As a big fan of STEM (science, tech, engineering and math) education, I was pleased to … Continue reading → [Read more...]

An R function to map your Twitter Followers

December 21, 2011 | leekgroup

I wrote a little function to make a personalized map of who follows you or who you follow on Twitter. The idea for this function was inspired by some plots I discussed in a previous post. I also found a lot of really useful code over at flowing data he... [Read more...]

Diagram for a Bernoulli process (using R)

November 10, 2011 | Tal Galili

A Bernoulli process is a sequence of Bernoulli trials (the realization of n binary random variables), taking two values (0/1, Heads/Tails, Boy/Girl, etc…). It is often used in teaching introductory probability/statistics classes about the binomial distribution. When visualizing a Bernoulli process, it is common to use a binary ... [Read more...]

Mapping Hotspots with R: The GAM

October 25, 2011 | john.nelson

I've been getting a lot of questions about the method used to map the hotspots in the seasonal drunk-driving risk maps.  It uses the GAM (Geographical Analysis Machine), a way of detecting spatial clusters from two data inputs: the data of interes...
[Read more...]

Shipping Mix

October 20, 2011 | john.nelson

With a fresh pile of historical global shipping data, we came back to the flow visualizations that illustrated tangible supply lines that facilitate global trade.  This time we've isolated two types of shipping vessels, cargo and tanker, in order ...
[Read more...]

vectorplot in rasterVis

October 2, 2011 | Oscar Perpiñán Lamigueiro

The function slopeAspect from raster provides the vector field (gradient) from a scalar field stored in a RasterLayer object. The magnitude (slope) and direction (aspect) of the vector field is usually displayed with a set of arrows (e.g. quiver in Matlab). rasterVis includes now a method, vectorplot, to calculate ... [Read more...]

hacking .gov shortened links

July 30, 2011 | Harlan

This past Friday, the web portal to the US Federal government,, organized hackathons across the US for programmers and data scientists to work with and analyze the data from their link-shortening service. It turns out that if you shorten a web link with, the shortened link ... [Read more...]

Scatterplot matrices in R

July 25, 2011 | Stephen Turner

I just discovered a handy function in R to produce a scatterplot matrix of selected variables in a dataset. The base graphics function is pairs(). Producing these plots can be helpful in exploring your data, especially using the second method below.Try...
[Read more...]


July 6, 2011 | Oscar Perpiñán Lamigueiro

The raster package defines classes and methods for spatial raster data access and manipulation. The new rasterVis package complements raster providing a set of methods for enhanced visualization and interaction. It is now at CRAN. Several examples can ... [Read more...]

Raster, CMSAF and solaR

June 17, 2011 | Oscar Perpiñán Lamigueiro

The Satellite Application Facility on Climate Monitoring (CMSAF) generates, archives and distributes widely recognised high-quality satellite-derived products and services relevant for climate monitoring in operational mode. The data is freely accesible here after a registration process. I have ask them for several files with monthly averages of global solar radiation ... [Read more...]

Sustainable Futures conference in Manchester

May 2, 2011 | Oscar Perpiñán Lamigueiro

Recently, Kevin Ummel gave a short conference about his PhD research at the Sustainable futures – Tyndall Centre researchers’ international conference. His work, named “Optimizing worldwide deployment of wind and solar power technologies via a high resolution, linear programming model”, is built with R. He is using the solaR package for ... [Read more...]

Here comes the sun

May 1, 2011 | Oscar Perpiñán Lamigueiro

The solar irradiance incident outside the earth’s atmosphere is called the extraterrestial or extra-atmospheric irradiance. It is derived from the solar constant only with geometric equations. It can be easily calculated with the calcSol function of the solaR package. With this post I will show an example with some ... [Read more...]

Alpha shapes with R and lattice

April 7, 2011 | Oscar Perpiñán Lamigueiro

What are the alpha shapes?: “The concept of alpha shapes formalizes the intuitive notion of “shape” for spatial point set data, which occurs frequently in the computational sciences. An alpha shape is a concrete geometric object that is uniquely defined for a particular point set.[...] Alpha shapes are generalizations of ... [Read more...]

Maps of solar radiation

April 2, 2011 | Oscar Perpiñán Lamigueiro

The Atmospheric Science Data Center (ASDC) at NASA Langley Research Center offers several data sources. For example, it is possible to download a text file with the 22-year (July 1983 – June 2005) monthly and annual average of global horizontal irradiation. nasafile [Read more...]
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