Plot Offset Polygons

Plot the offset polygons generated by the `generate_offset_polygon` function.

plot_offset_polygon(
  offset_polygons,
  plot_original_polygon = TRUE,
  fill = NA,
  color = "dodgerblue",
  xlim = NULL,
  ylim = NULL,
  linewidth = 1,
  background = "white",
  plot_skeleton = FALSE,
  return_layers = FALSE,
  ...
)

Arguments

offset_polygons

Default `NULL`. A `rayskeleton_polygon` or `rayskeleton_polygon_list` object, generated from `generate_offset_polygon()`.

plot_original_polygon

Default `TRUE`. Whether to plot the original polygon.

fill

Default `NULL`. A color or palette function to generate the fill palette for the polygons' interiors.

color

Default `grDevices::heat.colors`. A color or palette function to generate the color palette for the offset polygons' borders.

xlim

Default `NULL`. The x-axis limits as a vector of two values (min, max). If `NULL`, it calculates the limits from the data.

ylim

Default `NULL`. The y-axis limits as a vector of two values (min, max). If `NULL`, it calculates the limits from the data.

linewidth

Default `1`. The linewidth of the polygon.

background

Default `"white"`. Background color.

plot_skeleton

Default `FALSE`. Whether to plot the straight skeleton.

return_layers

Default `FALSE`, plots the figure. If `TRUE`, this will instead return a list of the ggplot layers.

...

Additional arguments to pass to `plot_skeleton()` if `plot_skeleton = TRUE`

Value

A plot showing the offset polygons.

Examples

# Outer polygon
vertices = matrix(c(0,0, 7,0, 7,7, 0,7, 0,0), ncol = 2, byrow = TRUE)
# Holes inside the polygon
hole_1 = matrix(c(1,1, 2,1, 2,2, 1,2, 1,1), ncol = 2, byrow = TRUE)[5:1,]
hole_2 = matrix(c(5,5, 6,5, 6,6, 5,6, 5,5), ncol = 2, byrow = TRUE)[5:1,]
skeleton = skeletonize(vertices, holes = list(hole_1, hole_2))
plot_skeleton(skeleton)


#Generate three offsets with the skeleton
plot_offset_polygon(generate_offset_polygon(skeleton, c(0.25,0.75,1.5,2)), plot_skeleton = TRUE)


#Generate many offsets
plot_offset_polygon(generate_offset_polygon(skeleton, seq(0.05,2.55,by=0.1)))


#Pass a palette
plot_offset_polygon(generate_offset_polygon(skeleton, seq(0.05,2.55,by=0.1)),
                    color = heat.colors)


#Pass colors manually (colors in excess of the number of offsets are ignored)
plot_offset_polygon(generate_offset_polygon(skeleton, seq(0.05,2.55,by=0.1)),
                    color = rep(c("red","red","blue","blue"),100))


# Skeletonize and plot an {sf} object
if(length(find.package("spData",quiet = TRUE)) > 0) {
  us_states = spData::us_states
  texas = us_states[us_states$NAME == "Texas",]
  texas_skeleton = skeletonize(texas)
  plot_offset_polygon(generate_offset_polygon(texas_skeleton, seq(0, 2.5, by = 0.1)),
                      color = heat.colors,
                      linewidth = 1)
}