ggtern - fill/smooth area between values of triangulation points-CodePudding

I am using ggtern and want to create a plot where the area between points of the triangle is filled/smoothed based on point values at each triangulation point. Something like below... target plot

But what I get so far is... current state

Below some data and code example.

Thank you for your help!

a <- c(1.0, 0.0, 0.0, 0.0, 0.0, 0.9, 0.9, 0.1, 0.1, 0.8, 0.0, 0.0, 0.2, 0.2, 0.8, 0.3, 0.7, 0.0, 0.0, 0.3, 0.7, 0.0, 0.4, 0.0, 0.6, 0.6, 0.4, 0.5, 0.0, 0.5, 0.1, 0.1, 0.8, 0.7, 0.1, 0.2, 0.1, 0.7,
    0.2, 0.6, 0.1, 0.1, 0.6, 0.3, 0.3, 0.1, 0.5, 0.1, 0.4, 0.5, 0.4, 0.6, 0.2, 0.2, 0.3, 0.5, 0.2, 0.5, 0.2, 0.3, 0.4, 0.4, 0.2, 0.3, 0.3, 0.4)
b <- c(0.0, 0.0, 1.0, 0.1, 0.9, 0.0, 0.1, 0.9, 0.0, 0.0, 0.8, 0.2, 0.8, 0.0, 0.2, 0.0, 0.3, 0.7, 0.3, 0.7, 0.0, 0.6, 0.0, 0.4, 0.0, 0.4, 0.6, 0.5, 0.5, 0.0, 0.1, 0.8, 0.1, 0.1, 0.2, 0.7, 0.7, 0.2,
     0.1, 0.1, 0.3, 0.6, 0.3, 0.6, 0.1, 0.4, 0.1, 0.5, 0.1, 0.4, 0.5, 0.2, 0.6, 0.2, 0.5, 0.3, 0.3, 0.2, 0.5, 0.2, 0.4, 0.2, 0.4, 0.4, 0.3, 0.3)
c <- c(0.0, 1.0, 0.0, 0.9, 0.1, 0.1, 0.0, 0.0, 0.9, 0.2, 0.2, 0.8, 0.0, 0.8, 0.0, 0.7, 0.0, 0.3, 0.7, 0.0, 0.3, 0.4, 0.6, 0.6, 0.4, 0.0, 0.0, 0.0, 0.5, 0.5, 0.8, 0.1, 0.1, 0.2, 0.7, 0.1, 0.2, 0.1,
     0.7, 0.3, 0.6, 0.3, 0.1, 0.1, 0.6, 0.5, 0.4, 0.4, 0.5, 0.1, 0.1, 0.2, 0.2, 0.6, 0.2, 0.2, 0.5, 0.3, 0.3, 0.5, 0.2, 0.4, 0.4, 0.3, 0.4, 0.3)
value <- c(1.433, 0.251, 0.000, 0.176, 0.000, 1.556, 1.490, 0.087, 0.522, 1.718, 0.000, 0.098, 0.347, 0.772, 1.642, 1.093, 1.762, 0.000, 0.052, 0.713, 1.857, 0.000, 1.367, 0.022, 1.814,
       1.726, 1.043, 1.424, 0.001, 1.722, 0.428, 0.122, 1.656, 1.798, 0.330, 0.384, 0.138, 1.777, 0.661, 1.763, 0.271, 0.166, 1.733, 0.753, 0.984, 0.236, 1.574, 0.204, 1.232, 1.471,
       1.086, 1.748, 0.409, 0.568, 0.790, 1.505, 0.520, 1.552, 0.451, 0.884, 1.094, 1.180, 0.484, 0.831, 0.859, 1.123)
df <- data.frame(a,b,c,value)

library(ggtern)
ggtern(df,aes(a, b, c))  
geom_point(size=2, aes(color=value))  
theme_rgbw()

CodePudding user response：

Applying the example in the ggtern package documentation you could try this. You'll probably have to experiment with the inputs and arguments to get the result you require, but this should provide a start. Edited arguments to make more like OP request for distinct fill areas and remove points, and grid ontop, now.


library(ggtern)
ggtern(df, aes(a, b, c, value = value))  
  stat_interpolate_tern(geom="polygon",
                        formula = value~y x,
                        method = lm,
                        n = 100,
                        breaks = seq(0, 2.5, length.out = 8),
                        aes(fill = ..level..),
                        expand = 1)  
  scale_fill_gradient(low = "green", high = "red") 
  theme_rgbw() 
  theme(tern.panel.grid.ontop = TRUE)

^{Created on 2021-09-16 by the reprex package (v2.0.0)}