element_path {ggpath}

Theme Element for Image Grobs

Description

In conjunction with the ggplot2::theme system, the function element_path() enables images in non-data components of the plot, e.g. axis text. It draws images from valid image URLs, raster objects, or bitmap arrays.

Usage

element_path(
  alpha = NULL,
  colour = NA,
  hjust = NULL,
  vjust = NULL,
  color = NULL,
  angle = NULL,
  size = 0.5
)

Arguments

alpha

The alpha channel, i.e. transparency level, as a numerical value between 0 and 1.

colour, color

The image will be colorized with this color. Use the special character "b/w" to set it to black and white. For more information on valid color names in ggplot2 see https://ggplot2.tidyverse.org/articles/ggplot2-specs.html?q=colour#colour-and-fill.

hjust, vjust

The horizontal and vertical adjustment respectively. Must be a numerical value between 0 and 1.

angle

The angle of the element as a numerical value between 0° and 360°.

size

The output grob size in cm (!).

Value

An S3 object of class element.

See Also

geom_from_path() for more information.

Examples

library(ggplot2)
library(ggpath)

# compute path of an R logo file shipped with ggpath
local_image_path <- system.file("r_logo.svg", package = "ggpath")

# create dataframe with x-y-coordinates and the above local path
plot_data <- data.frame(x = c(-1, 1), y = 1, path = local_image_path)

# Replace title, subtitle, the caption, axis labels as well as y-axis text
# the the local image
ggplot(plot_data, aes(x = x, y = local_image_path)) +
  theme_minimal() +
  labs(
    title = local_image_path,
    subtitle = local_image_path,
    x = local_image_path,
    y = local_image_path,
    caption = local_image_path
  ) +
  theme(
    plot.caption = element_path(hjust = 1, size = 0.6),
    axis.text.y = element_path(size = 1),
    axis.title.x = element_path(),
    axis.title.y = element_path(vjust = 0.9),
    plot.title = element_path(hjust = 0, size = 2, alpha = 0.5),
    plot.subtitle = element_path(hjust = 0.9, angle = 45),
  )