Sean Mulcahy made an example of plotting Elkin and Grove's 1990 Feldspar Data. Here is an equivalent plot in three variables:

1. Phase (Shape)
2. Temperature (Color Gradient), and;
3. Pressure (Size)

Code to Produce the Above…

# Load data
data(Feldspar)

# Sort it by decreasing pressure 
# (so small grobs sit on top of large grobs
Feldspar <- Feldspar[with(Feldspar, order(-P.Gpa)), ]

# Build and Render the Plot
ggtern(data = Feldspar, aes(x = An, y = Ab, z = Or)) + 
    #the layer
    geom_point(aes(fill = T.C, 
                   size = P.Gpa, 
                   shape = Feldspar)) + 
    #scales
    scale_shape_manual(values = c(21, 24)) + 
    scale_size_continuous(range = c(2.5, 7.5)) + 
    scale_fill_gradient(low = "green", high = "red") + 

    #theme tweaks
    theme_tern_bw()  + 
    theme(legend.position      = c(0, 1), 
          legend.justification = c(0, 1), 
          legend.box.just      = "left") + 
    
    #tweak guides
    guides(shape= guide_legend(order   =1,
                               override.aes=list(size=5)),
           size = guide_legend(order   =2),
           fill = guide_colourbar(order=3)) +

    #labels and title
    labs(size = "Pressure/GPa", 
         fill = "Temperature/C") + 
    ggtitle("Feldspar - Elkins and Grove 1990")

The post Feldspar appeared first on ggtern: ternary diagrams in R.