Rectangles • ggdiagram

Setup

Packages

library(ggdiagram)
library(ggplot2)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(ggtext)
library(ggarrow)
library(arrowheadr)

Base Plot

To avoid repetitive code, we make a base plot:


my_font <- "Roboto Condensed"
my_font_size <- 20
my_point_size <- 2
my_arrowhead <- arrowheadr::arrow_head_deltoid(d = 2.3, n = 100)

# my_colors <- viridis::viridis(2, begin = .25, end = .5)
my_colors <- c("#3B528B", "#21908C")

theme_set(
  theme_minimal(
    base_size = my_font_size,
    base_family = my_font) +
    theme(axis.title.y = element_text(angle = 0, vjust = 0.5)))

bp <- ggdiagram(
  font_family = my_font,
  font_size = my_font_size,
  point_size = my_point_size,
  linewidth = .5,
  theme_function = theme_minimal,
  axis.title.x =  element_text(face = "italic"),
  axis.title.y = element_text(
    face = "italic",
    angle = 0,
    hjust = .5,
    vjust = .5)) +
  scale_x_continuous(labels = signs_centered,
                     limits = c(-4, 4)) +
  scale_y_continuous(labels = signs::signs,
                     limits = c(-4, 4))

my_colors <- list(
  primary = class_color("royalblue4"),
  secondary = class_color("firebrick4"),
  tertiary = class_color("orchid4"))

Specifying a Rectangle

A rectangle has 4 corners (northeast, northwest, southwest, and southeast). It has a center. It has width and height. For the purpose of demonstration, we can specify all these features, though in practice not all of them are necessary.

# northeast corner
ne <- ob_point(4,2) 
# northwest corner
nw <- ob_point(0,2)
# southwest corner
sw <- ob_point(0,0)
# southeast corner
se <- ob_point(4,0)
# center point
cent <- ob_point(2,1)
# width
w <- 4
# height
h <- 2

If you give the rectangle function enough information to deduce where its four corners will be, all other features will be calculated. All of the following will give the same rectangle:

Give width, height, and any point

An easy way to specify a rectangle is to specify its width and height and any of its points. All the following rectangles are equivalent.

Center, width, and height

r1 <- ob_rectangle(
  width = w,
  height = h,
  center = cent,
  color = my_colors$primary,
  fill = my_colors$primary@transparentize(.15),
  linewidth = 1
)
r1
#> <ob_rectangle>
#> @ center: <ob_point>
#>  @ x: num 2
#>  @ y: num 1
#> @ width : num 4
#> @ height: num 2
#> Other props: label, angle, vertex_radius, alpha, color, fill,
#>              linewidth, linetype, area, bounding_box, perimeter,
#>              northeast, northwest, southwest, southeast, east,
#>              north, west, south, side, length, style, tibble, geom,
#>              normal_at, place, point_at, aesthetics

Code

double_arrowstyle <- ob_style(
  arrow_head = arrow_head_deltoid(),
  arrow_fins = arrow_head_deltoid(),
  color = my_colors$secondar
)

s_east <- r1@side@east@nudge(x = .1)
s_east@style <- double_arrowstyle

s_north <- r1@side@north@nudge(y = .1)
s_north@style <- double_arrowstyle

rc_plot <- ggplot() +
  coord_equal(ylim = c(0, 2.2)) +
  scale_y_continuous(breaks = -10:10) +
  r1

rc_center <- list(
  r1@center,
  r1@center@label(
    fill = my_colors$primary@lighten(.15), 
    vjust = -.15)) |>
  bind()

rc_width <- s_north |> 
  set_props(label = ob_label(
    label = paste0("Width = ", r1@width),
    center = midpoint(s_north),
    color = my_colors$secondary,
    vjust = 0,
    label.margin = ggplot2::margin(2, 2, 2, 2, "pt")
  ))

rc_height <- s_east |> 
  set_props(label = ob_label(
    label = paste0("Height = ", r1@height),
    center  = midpoint(s_east),
    vjust = 0,
    color = my_colors$secondary,
    angle = -90))


rc_nw <- r1@northwest@label(
  plot_point = T,
  vjust = 1.1,
  hjust = 0,
  fill = my_colors$primary@lighten(.15)
)

rc_ne <- r1@northeast@label(
  plot_point = T,
  vjust = 1.1,
  hjust = 1,
  fill = my_colors$primary@lighten(.15)
)

rc_sw <- r1@southwest@label(
  plot_point = T,
  vjust = -.1,
  hjust = 0,
  fill = my_colors$primary@lighten(.15)
)

rc_se <- r1@southeast@label(
  plot_point = T,
  vjust = -.1,
  hjust = 1,
  fill = my_colors$primary@lighten(.15)
)

rc_plot + rc_center + rc_width + rc_height

Northeast corner, width, and height

r1 == ob_rectangle(width = w,
                height = h,
                northeast = ne)
#> [1] TRUE

Code

rc_plot + rc_width + rc_height + rc_ne

Figure 2: Specify a rectangle with height, width, and the northeast corner

Give the center and any of the 4 corners

A rectangle can be specified with the center and any other corner. The following rectangles are equivalent.

For example:

r1 == ob_rectangle(center = cent, 
                northeast = ne)
#> [1] TRUE

Code

rc_plot + rc_center + rc_ne

Figure 3: Specify a rectangle with the center and the northeast corner

Give opposite corners

A rectangle can be specified with points from opposite corners. These rectangles are equivalent.

For example,

r1 == ob_rectangle(
  northeast = ne, 
  southwest = sw)
#> [1] TRUE

Code

rc_plot + rc_sw + rc_ne

Figure 4: Specify a rectangle with the northeast and southwest corners

Give width and two points on either side

A rectangle can be specified with the width and 2 points from the left or right side. These rectangles are equivalent.

r1 == ob_rectangle(width = w,
                northwest = nw,
                southwest = sw)
#> [1] TRUE

Code

rc_plot + rc_width + rc_nw + rc_sw

Figure 5: Specify a rectangle with the width and the left corners

Give height and two points on top or bottom

A rectangle can be specified with the height and 2 points from the top or bottom side. These rectangles are equivalent.

For example,

r1 == ob_rectangle(height = h,
                northwest = nw,
                northeast = ne)
#> [1] TRUE

Code

rc_plot + rc_height + rc_ne + rc_nw

Figure 6: Specify a rectangle with the height and the top corners

Rectangle points

The corners and side midpoints can be extracted. Here is the north point (i.e., the midpoint of the north side):

r1@north
#> <ob_point>
#> @ x: num 2
#> @ y: num 2
#> Other props: alpha, color, fill, shape, size, stroke, auto_label,
#>              bounding_box, length, r, theta, style, tibble, xy,
#>              geom, label, place, aesthetics

Code

rc_plot +
  purrr::map(
    c(
      "east",
      "north",
      "west",
      "south",
      "northeast",
      "northwest",
      "southeast",
      "southwest",
      "center"
    ),
    \(x) {
      v <- ifelse(grepl(x = x, "north"),
        1.1,
        ifelse(grepl(x = x, "south|center"), 
               -.1, 
               .5))
      h <- ifelse(grepl(x = x, "east"),
                  1.1,
                  ifelse(grepl(x = x, "west"), -.1, .5))
      c(
        as.geom(
          prop(r1, x)@label(
            label = x,
            hjust = h,
            vjust = v,
            fill = my_colors$primary@lighten(.15)
          )
        ),
        as.geom(
          prop(r1, x)@label(hjust = 1 - h, vjust = 1 - v),
          fill = ifelse(x == "center", 
                        my_colors$primary@lighten(.15), 
                        "white")
        ),
        as.geom(prop(r1, x))
      )
    }
  ) +
  coord_equal(xlim = c(-.25, 4.25), ylim = c(-.25, 2.25))

Figure 7: The named points of a rectangle

Points at any angle

theta <- degree(60)
r1@point_at(theta)
#> <ob_point>
#> @ x: num 2.58
#> @ y: num 2
#> Other props: alpha, color, fill, shape, size, stroke, auto_label,
#>              bounding_box, length, r, theta, style, tibble, xy,
#>              geom, label, place, aesthetics

Code

r1_theta <- r1@point_at(theta)

rc_plot +
  ob_segment(r1@center, r1_theta) +
  r1_theta@label(
    polar_just = ob_polar(theta, 1.5), 
    plot_point = T) +
  ob_arc(center = r1@center,
      radius = .5,
      end = theta,
      label = ob_label(theta, 
                    fill = my_colors$primary@lighten(.15), 
                    color = my_colors$primary@color))

Figure 8: The point on a rectangle at angle θ = 60°

Rectangle sides

Each side of the rectangle can be extracted. For example, here is the north side segment:

r1@side@north
#> <ob_segment>
#> @ p1: <ob_point>
#>  @ x: num 0
#>  @ y: num 2
#> @ p2: <ob_point>
#>  @ x: num 4
#>  @ y: num 2

Code

rc_plot + 
  r1@side@north |>
    set_props(color = my_colors$secondary@color, linewidth = 2) +
  r1@north@label(label = "North Side",
                 vjust = -.1, 
                 size = 20,
                 color = my_colors$secondary)

Rounded corners

The @radius property controls the radius of the rounded corners. It must be of length 1. It can be given in as a ggplot2::unit or as a numeric value. If numeric, it is understood as a proportion of the plot area width. Rounding does not affect the location of corners.

ggplot() +
  coord_equal(xlim = c(-4, 4), 
              ylim = c(-4, 4)) +
  ob_rectangle(
    ob_point(0, 0),
    width = 6,
    height = 4,
    radius = unit(5, "mm")
  )

Figure 10: Specify a rectangle rounded corners

Rotation angle

It is possible to rotate a rectangle.

ggplot() +
  coord_equal(xlim = c(-4, 4), 
              ylim = c(-4, 4)) +
  ob_rectangle(
    center = ob_point(0, 0),
    width = 6,
    height = 2,
    angle = 30,
    radius = unit(3, "mm")
  )

Many angles can be specified at once:

# Angles
th <- degree(seq(0, 355, 5))
# Radius of middle space
r_middle <- sqrt(2)
# Rectangle width
w <- 4 - r_middle

ggplot() +
  coord_equal(xlim = c(-4, 4), 
              ylim = c(-4, 4)) +
  ob_rectangle(
    center = ob_polar(theta = th, 
                   r = w / 2 + r_middle),
    width = w,
    height = .15,
    angle = th,
    color = NA,
    fill = hcl(th@degree)
  )