1row per point, many points per classification representing the extremes of the area.
Soil Mechanics Level 1, Module 3, USDA Textural Classification Study Guide
This dataset was issued by the United States Department of Agriculture (USDA) in the form of a ternary diagram, this original ternary diagram has been converted to numerical data and included here.
data(USDA)
#Load the Libraries library(ggtern) library(plyr) #Load the Data. data(USDA) #Put tile labels at the midpoint of each tile. USDA.LAB <- ddply(USDA,"Label",function(df){ apply(df[,1:3],2,mean) }) #Tweak USDA.LAB$Angle = sapply(as.character(USDA.LAB$Label),function(x){ switch(x,"Loamy Sand"=-35,0) }) #Construct the plot. ggtern(data=USDA,aes(Sand,Clay,Silt,color=Label,fill=Label)) + geom_polygon(alpha=0.75,size=0.5,color="black") + geom_mask() + geom_text(data=USDA.LAB,aes(label=Label,angle=Angle),color="black",size=3.5) + theme_rgbw() + theme_showsecondary() + theme_showarrows() + weight_percent() + guides(fill='none') + theme_legend_position("topleft") + labs(title = "USDA Textural Classification Chart", fill = "Textural Class", color = "Textural Class")