library(ggtern)
library(grid)

g <- data.frame(y=c(1,0,0),
                x=c(0,1,.4),
                z=c(0,0,.6),         Series="Green")

p <- data.frame(y=c(1,0.475,0.6),
                x=c(0,0.210,0),
                z=c(0,0.315,.4),         Series="Red")

q <- data.frame(y=c(0.575,0.475,0.0,0.0),
                x=c(0.040,0.210,0.4,0.1),
                z=c(0.385,0.315,0.6,0.9),         Series="Yellow")

f <- data.frame(y=c(0.6,0.575,0.0,0.0),
                x=c(0.0,0.040,0.1,0.0),
                z=c(0.4,0.385,0.9,1.0),         Series="Blue")

DATA = rbind(g, p, q, f)
p <- ggtern(data=DATA,aes(x,y,z)) +
  geom_polygon(aes(fill=Series),alpha=.5,color="black",size=0.25) +
  scale_fill_manual(values=as.character(unique(DATA$Series))) +
  theme(legend.position=c(0,1),legend.justification=c(0,1)) +
  labs(fill="Region",title="Sample Filled Regions")+
  xlab("X=60")+ylab("Y=60")+zlab("Z=90")

gt <- ggplot_gtable(ggplot_build(p))
grobPanel <- gt$grobs[[which(gt$layout$name == "panel")]]
grobLabels <- grobPanel$children[[length(grobPanel$children)]]
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[2]]$x <- unit(0.6,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[2]]$y <- unit(0.1,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[2]]$gp$fontsize <- 14

gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[1]]$x <- unit(0.7,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[1]]$y <- unit(0.6,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[1]]$gp$fontsize <- 14

gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[3]]$x <- unit(0.75,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[3]]$y <- unit(0.1,"npc")
gt$grobs[[which(gt$layout$name == "panel")]]$children[[length(grobPanel$children)]]$children[[3]]$gp$fontsize <- 14

grid.draw(gt)