Exploring data with Gadfly

Gadfly is a Julia implementation of A Layered Grammar of Graphics. However, some aspects will change from the grammar described initially for the R language. In this section, we will learn how to write the different grammar components using Julia and Gadfly. As with other grammar implementations, Gadfly makes extensive use of defaults to determine the unspecified components. This will allow us to start with a simple plot and build a more complex specification. Let’s explore Gadfly and its syntax by plotting the data in the Iris dataset:

1. Execute the following code in the first cell:

   begin
       import Pkg
       Pkg.activate(mktempdir())
       Pkg.add([
           Pkg.PackageSpec(name="RDatasets",
              version="0.7.7"),
           Pkg.PackageSpec...