Paths

Setup

Packages

library(ggdiagram)
library(ggplot2)
library(dplyr)
library(ggtext)
library(ggarrow)

Base Plot

To avoid repetitive code, we make a base plot:

my_font <- "Roboto Condensed"
my_font_size <- 20
my_point_size <- 2


# 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 = 0.5,
  theme_function = theme_minimal,
  axis.title.x =  element_text(face = "italic"),
  axis.title.y = element_text(
    face = "italic",
    angle = 0,
    hjust = 0.5,
    vjust = 0.5)) +
  scale_x_continuous(labels = signs_centered,
                     limits = c(-4, 4)) +
  scale_y_continuous(labels = signs::signs,
                     limits = c(-4, 4))

Paths

The path function creates an object that connects points along a path.

p <- ob_point(c(-4,-3,4), c(0,-2, 0), color = "dodgerblue")
bp + 
  ob_path(p) +
  p

Figure 1: Plotting a path.

Path Labels

The label of a path is created with geomtextpath::geom_labelpath, and thus will curve if the path is curved.

p_curve <- tibble(x = seq(-4, 4, 0.1), 
                  y = (pnorm(x) * 8 - 4)) |>
  ob_point()



bp +
  ob_path(
    p = p_curve,
    label = ob_label(
      "A path label will curve along the path.",
      vjust = -0.1,
      size = 20,
      color = "dodgerblue4"
    ),
    arrowhead_length = 8,
    arrow_head = arrowhead()
  )

Figure 2: A path with a curved label

You can control the position of the path label with either the label’s position or hjust properties.

bp +
  ob_path(
    p = p_curve,
    label = ob_label(
      "A path label will curve along the path.",
      vjust = -0.1,
      size = 20,
      color = "dodgerblue4",
      position = 0.1
    ),
    arrowhead_length = 8,
    arrow_head = arrowhead()
  )

Figure 3: A path with a curved label at position .1

Multiple paths

To create multiple paths at once, specify a list or vector of point objects.

bp +
  ob_path(c(p_curve, 
         p_curve * 0.5 + ob_point(2,-2),
         p_curve * 0.5 + ob_point(-2,2)), 
       color = c("orchid4",
                 "dodgerblue3",
                 "firebrick4"),
       label = c(".52", ".42", ".61"))

Figure 4: Multiple paths

Color Gradients

It is possible to create color gradients along a path with the gradient parameter. The gradient runs in a straight line from the first point to the last point of the path, so it follows the path closely only when the path does not double back on itself.

You can use a vector of two or more colors.

ggdiagram() +
  ob_path(
    p_curve, 
    gradient = c("red", "yellow", "blue"),
    linewidth = 3)

Figure 5: Color Gradients

The colors can come from any palette function (here, with some transparency).

ggdiagram() +
  ob_path(
    p_curve, 
    gradient = viridis::viridis(10, alpha = .5),
    linewidth = 3)

Figure 6: Color Gradients with a function