Plotting labels from files

In Chapter 2, Annotating with Labels and Legends, we learned how to place a text label anywhere on the graph with the set label command. It is also possible to plot a set of labels whose text, positions, and possibly other attributes are derived from the information in a datafile. In this way, we can create visualizations such as the following:

The previous figure shows a collection of names of countries printed with a text size that is proportional to each country's population (aside from the practical requirement to impose a maximum and minimum font size). The labels are positioned to indicate each country's school intake rate in the first grade as a percentage of official school-age population versus the literacy rate for people in the age group 15-24. The data comes from the World Bank and can be found at http://data.worldbank.org/data-catalog/world-development-indicators. The numbers reported for 2009 are used, and all countries with data for that year are...