Colour a ternary plot according to the output of a function

Source: R/Contours.R

Colour a ternary plot according to the output of a function

ColourTernary(
  values,
  spectrum = viridisLite::viridis(256L, alpha = 0.6),
  resolution = sqrt(ncol(values)),
  direction = getOption("ternDirection", 1L),
  legend,
  ...
)

ColorTernary(
  values,
  spectrum = viridisLite::viridis(256L, alpha = 0.6),
  resolution = sqrt(ncol(values)),
  direction = getOption("ternDirection", 1L),
  legend,
  ...
)

Arguments

values

Numeric matrix, possibly created using TernaryPointValues(), with four named rows: x, y, cartesian coordinates of each triangle centre; z, value associated with that coordinate; down, triangle direction: 0 = point upwards; 1 = point downwards.

spectrum

Vector of colours to use as a spectrum, or NULL to use values["z", ].

resolution

The number of triangles whose base should lie on the longest axis of the triangle. Higher numbers will result in smaller subdivisions and smoother colour gradients, but at a computational cost.

direction

(optional) Integer specifying the direction that the current ternary plot should point: 1, up; 2, right; 3, down; 4, left.

legend

Character vector specifying annotations for colour scale. If not provided, no colour legend is displayed. Specify TRUE to generate automatically, or a single integer to generate legend annotations.

...

Further arguments to SpectrumLegend().

See also

Fine control over continuous legends: PlotTools::SpectrumLegend()

Other contour plotting functions: TernaryContour(), TernaryDensityContour(), TernaryPointValues()

Other functions for colouring and shading: TernaryTiles()

Examples

TernaryPlot(alab = "a", blab = "b", clab = "c")

FunctionToContour <- function (a, b, c) {
  a - c + (4 * a * b) + (27 * a * b * c)
}

values <- TernaryPointValues(FunctionToContour, resolution = 24L)
ColourTernary(
  values,
  x = "topleft",
  bty = "n", # No box
  legend = signif(seq(max(values), min(values), length.out = 4), 3)
)
TernaryContour(FunctionToContour, resolution = 36L)



TernaryPlot()
values <- TernaryPointValues(rgb, resolution = 20)
ColourTernary(values, spectrum = NULL)


# Create a helper function to place white centrally:
rgbWhite <- function (r, g, b) {
  highest <- apply(rbind(r, g, b), 2L, max)
  rgb(r/highest, g/highest, b/highest)
}

TernaryPlot()
values <- TernaryPointValues(rgbWhite, resolution = 20)
ColourTernary(values, spectrum = NULL)