Regular polygon grob

Regular polygons with optional rotation, stretching, and aesthetic attributes.

ngonGrob(x, y, n = 5, size = 5, phase = pi/2, angle = 0, ar = 1,
  gp = gpar(colour = "black", fill = NA, linejoin = "mitre"), ...,
  position.units = "npc", size.units = "mm")

grid.ngon(...)

ellipseGrob(x, y, size = 5, angle = pi/4, ar = 1, n = 50,
  gp = gpar(colour = "black", fill = NA, linejoin = "mitre"), ...,
  position.units = "npc", size.units = "mm")

grid.ellipse(...)

polygon_regular(n = 5, phase = 0)

Arguments

x	x unit
y	y unit
n	number of vertices
size	radius of circumscribing circle
phase	angle in radians of first point relative to x axis
angle	angle of polygon in radians
ar	aspect ratio
gp	gpar
...	further parameters passed to polygonGrob
position.units	default units for the positions
size.units	grid units for the sizes

Value

A grob.

Functions

• ngonGrob: return a polygon grob

• grid.ngon: draw a polygon grob on the current device

• ellipseGrob: return an ellipse grob

• grid.ellipse: draw an ellipse grob

• polygon_regular: return the x,y coordinates of a regular polygon inscribed in the unit circle

Examples

library(grid)
N <- 5
xy <- polygon_regular(N)*2

# draw multiple polygons
g <- ngonGrob(unit(xy[,1],"cm") + unit(0.5,"npc"),
              unit(xy[,2],"cm") + unit(0.5,"npc"),
              n = seq_len(N) + 2, gp = gpar(fill=1:N))

grid.newpage()
grid.draw(g)

# rotated and stretched
g2 <- ngonGrob(unit(xy[,1],"cm") + unit(0.5,"npc"),
              unit(xy[,2],"cm") + unit(0.5,"npc"),
              n = seq_len(N) + 2, ar = seq_len(N),
              phase = 0, angle = pi/(seq_len(N) + 2),
              size = 1:N + 5)

grid.newpage()
grid.draw(g2)

# ellipse
g3 <- ellipseGrob(unit(xy[,1],"cm") + unit(0.5,"npc"),
                  unit(xy[,2],"cm") + unit(0.5,"npc"),
                  angle = -2*seq(0,N-1)*pi/5 + pi/2,
                  size = 5, ar = 1/3)

grid.newpage()
grid.draw(g3)