Even though several examples of great circle visualizations exist by now, I had not seen the code of one made with ggplot2. Both solutions offered, here using plot and here using lattice, basically loop through the great circle lines ordered from low to high number of flights and overplot the lines with fewer counts, which are plotted in a light color with those with higher counts, which are plotted in a dark color.
In ggplot we can simply use the alpha parameter for transparency in combination with scale_colour_gradient to obtain a similar effect.
I am also addressing another issue here, namely the ability to flexibly recenter the world map to any longitude (not just 0 and 180) and to avoid the problem of split polygons.
Example data are all flights out of Beijing, China, downloaded from openflights.org.
Beijing - outgoing flights
Continue reading Great circles on a recentered worldmap, in ggplot
After last year’s experience with taking iPad to the field I am finally getting around to reporting back on the 4 week long field research experience with iPad this summer, when we were able to equip our whole field school team (the faculty, a graduate student TA, three undergraduate students and myself) with iPads. Goal for this year was to more extensively explore iPad as a team and to see where it might be useful as a research tool.
Continue reading iPad for research – one size fits all?
In an attempt to learn more about how to best and seamlessly import external geo data and map them in Drupal I recently mapped all the German soccer stadiums, that are listed in Wikipedia, and which I harvested from from DBpedia (as in the following screenshot).
This is how it worked for me. Continue reading Mapping DBPedia geodata in Drupal