A glyph is a symbol. In this section, we are looking to display glyphs at different points in a graph rather than the standard dot as the glyph should provide more visual information to the viewer. Often there is an attribute about a data point that can be used to turn the data point into a useful glyph, as we will see in the following examples.
The ggplot2 package is useful for visualizing data in a variety of ways. ggplot is described as a plotting system for R. We will look at an example that displays volcano data points across the globe. I used the information from the National Center for Environmental Information at https://www.ngdc.noaa.gov/nndc. I selected volcano information post-1964.
This generated a set of data that I copied into a local CSV file:
#read in the CSV file as available as described previouslyvolcanoes = read.csv("volcanoes.csv")head(volcanoes)
If we just plot out the points on a world map we can see where the volcanoes are located. We are...