Zoom on Plot Region
A series of convenience functions for the zooming in on the middle or apex regions to various degrees.
In these convenience functions, a single value of x is expected, which defines the values of the apex
limits other than the point of reference, for example, theme_zoom_T will fix the T limit 
at 1, and will adjust the balancing limits according to the argument x. Equivalent are also possible for
the L and R apexes, via the theme_zoom_L and theme_zoom_R functions respectively. 
Finally, the theme_zoom_center function will adjust all three apex limits, serving, as the name suggests, 
to act as a centred zoom. The examples below are fairly self explanatory.
theme_zoom_T(x = 1, ...) theme_zoom_L(x = 1, ...) theme_zoom_R(x = 1, ...) theme_zoom_center(x = 1, ...)
| x | numeric scalar | 
| ... | additional arguments to be passed through to  | 
Nicholas Hamilton
#Default Plot
data(Feldspar)
base = ggtern(Feldspar,aes(Ab,An,Or)) +
       theme_bw(8) +
       geom_density_tern() + 
       geom_point() + 
       labs(title="Original")
#Zoom on Left Region
A = base + theme_zoom_L(0.5) + labs(title="theme_zoom_L")
#Zoom on Right Region
B = base + theme_zoom_R(0.5) + labs(title="theme_zoom_R")
#Zoom on Top Region
C = base + theme_zoom_T(0.5) + labs(title="theme_zoom_T")
#Zoom on Center Region
D = base + theme_zoom_center(0.5) + labs(title="theme_zoom_center")
#Put all together for comparisons sake
grid.arrange(arrangeGrob(base), 
             arrangeGrob(A,B,nrow=1), 
             arrangeGrob(C,D,nrow=1), 
             ncol=1, heights=c(2,1,1),
             top = "Comparison of Zooming Functions")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.