TriangleCentres: Coordinates of triangle mid-points

In Ternary: Create Ternary and Holdridge Plots

Coordinates of triangle mid-points

Description

Calculate x and y coordinates of the midpoints of triangles tiled to cover a ternary plot.

Usage

TriangleCentres(resolution = 48L, direction = getOption("ternDirection", 1L))

Arguments

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.

Value

TriangleCentres() returns a matrix with three named rows:

• x x coordinates of triangle midpoints;

• y y coordinates of triangle midpoints;

• triDown 0 for upwards-pointing triangles, 1 for downwards-pointing.

Author(s)

Martin R. Smith ([e-mail])

See Also

Add triangles to a plot: TernaryTiles()

Other coordinate translation functions: ReflectedEquivalents(), TernaryCoords(), XYToTernary()

Other tiling functions: Polygon-Geometry, TriangleInHull()

Examples

TernaryPlot(grid.lines = 4)
centres <- TriangleCentres(4)
text(centres["x", ], centres["y", ], ifelse(centres["triDown", ], "v", "^"))

Ternary documentation built on Sept. 11, 2024, 6:39 p.m.