Ternary Diagram — ternaryplot • vcd

Visualizes compositional, 3-dimensional data in an equilateral triangle.

ternaryplot(x, scale = 1, dimnames = NULL,
  dimnames_position = c("corner","edge","none"),
  dimnames_color = "black", dimnames_rot = c(-60, 60, 0),
  id = NULL, id_color = "black",
  id_just = c("center", "center"),
  coordinates = FALSE, grid = TRUE, grid_color = "gray",
  labels = c("inside", "outside", "none"),
  labels_color = "darkgray", labels_rot = c(120, -120, 0),
  border = "black", bg = "white",
  pch = 19, cex = 1, prop_size = FALSE, col = "red",
  main = "ternary plot", newpage = TRUE, pop = TRUE,
  return_grob = FALSE, ...)

Arguments

x: a matrix with three columns.
scale: row sums scale to be used.
dimnames: dimension labels (defaults to the column names of x).
dimnames_position, dimnames_color: position and color of dimension labels.
dimnames_rot: Numeric vector of length 3, specifying the angle of the dimension labels.
id: optional labels to be plotted below the plot symbols. coordinates and id are mutual exclusive.
id_color: color of these labels.
id_just: character vector of length 1 or 2 indicating the justification of these labels.
coordinates: if TRUE, the coordinates of the points are plotted below them. coordinates and id are mutual exclusive.
grid: if TRUE, a grid is plotted. May optionally be a string indicating the line type (default: "dotted").
grid_color: grid color.
labels, labels_color: position and color of the grid labels.
labels_rot: Numeric vector of length 3, specifying the angle of the grid labels.
border: color of the triangle border.
bg: triangle background.
pch: plotting character. Defaults to filled dots.
cex: a numerical value giving the amount by which plotting text and symbols should be scaled relative to the default. Ignored for the symbol size if prop_size is not FALSE.
prop_size: if TRUE, the symbol size is plotted proportional to the row sum of the three variables, i.e., represents the weight of the observation.
col: plotting color.
main: main title.
newpage: if TRUE, the plot will appear on a new graphics page.
pop: logical; if TRUE, all newly generated viewports are popped after plotting.
return_grob: logical. Should a snapshot of the display be returned as a grid grob?
...: additional graphics parameters (see par)

Details

A points' coordinates are found by computing the gravity center of mass points using the data entries as weights. Thus, the coordinates of a point \(P(a,b,c)\), \(a + b + c = 1\), are: \(P(b + c/2, c \sqrt{3}/2)\).

References

M. Friendly (2000), Visualizing Categorical Data. SAS Institute, Cary, NC.

Author

David Meyer David.Meyer@R-project.org

Examples

data("Arthritis")

## Build table by crossing Treatment and Sex
tab <- as.table(xtabs(~ I(Sex:Treatment) + Improved, data = Arthritis))

## Mark groups
col <- c("red", "red", "blue", "blue")
pch <- c(1, 19, 1, 19)

## plot
ternaryplot(
            tab,
            col = col,
            pch = pch,
            prop_size = TRUE,
            bg = "lightgray",
            grid_color = "white",
            labels_color = "white",
            main = "Arthritis Treatment Data"
           )
## legend
grid_legend(0.8, 0.7, pch, col, rownames(tab), title = "GROUP")


## Titanic
data("Lifeboats")
attach(Lifeboats)
#> The following objects are masked from Lifeboats (pos = 3):
#> 
#>     boat, cap, crew, launch, men, side, total, women
#> The following object is masked from package:datasets:
#> 
#>     women
ternaryplot(
  Lifeboats[,4:6],
  pch = ifelse(side == "Port", 1, 19),
  col = ifelse(side == "Port", "red", "blue"),
  id  = ifelse(men / total > 0.1, as.character(boat), NA),
  prop_size = 2,
  dimnames_position = "edge",
  main = "Lifeboats on Titanic"
)
grid_legend(0.8, 0.9, c(1, 19),
  c("red", "blue"), c("Port", "Starboard"),
  title = "SIDE")



## Hitters
data("Hitters")
attach(Hitters)
colors <- c("black","red","green","blue","red","black","blue")
pch <- substr(levels(Positions), 1, 1)
ternaryplot(
  Hitters[,2:4],
  pch = as.character(Positions),
  col = colors[as.numeric(Positions)],
  main = "Baseball Hitters Data"
)
grid_legend(0.8, 0.9, pch, colors, levels(Positions),
  title = "POSITION(S)")