cowplot: draw_image – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

draw_image

Draw an image

Description

Places an image somewhere onto the drawing canvas. By default, coordinates run from 0 to 1, and the point (0, 0) is in the lower left corner of the canvas. Requires the magick package to work, and fails gracefully if that package is not installed.

Usage

draw_image(
  image,
  x = 0,
  y = 0,
  width = 1,
  height = 1,
  scale = 1,
  clip = "inherit",
  interpolate = TRUE,
  hjust = 0,
  vjust = 0,
  halign = 0.5,
  valign = 0.5
)

Arguments

`image`	The image to place. Can be a file path, a URL, or a raw vector with image data, as in `magick::image_read()`. Can also be an image previously created by `magick::image_read()` and related functions.
`x`	The x location of the image. (Left side if `hjust = 0`.)
`y`	The y location of the image. (Bottom side if `vjust = 0`.)
`width`	Width of the image.
`height`	Height of the image.
`scale`	Scales the image relative to the rectangle defined by `x`, `y`, `width`, `height`. A setting of `scale = 1` indicates no scaling.
`clip`	Set to "on" to clip the image relative to the box into which it is draw (useful for `scale > 1`). Note that clipping doesn't always work as expected, due to limitations of the grid graphics system.
`interpolate`	A logical value indicating whether to linearly interpolate the image (the alternative is to use nearest-neighbour interpolation, which gives a more blocky result).
`hjust, vjust`	Horizontal and vertical justification relative to x.
`halign, valign`	Horizontal and vertical justification of the image inside the box.

Examples

library(ggplot2)

# Use image as plot background
p <- ggplot(iris, aes(x = Sepal.Length, fill = Species)) +
  geom_density(alpha = 0.7) +
  scale_y_continuous(expand = expansion(mult = c(0, 0.05))) +
  theme_half_open(12)

logo_file <- system.file("extdata", "logo.png", package = "cowplot")
ggdraw() +
  draw_image(
    logo_file, scale = .7
  ) +
  draw_plot(p)

# Place in lower right corner
ggdraw() +
  draw_image(
    logo_file, scale = .3, x = 1,
    hjust = 1, halign = 1, valign = 0
  ) +
  draw_plot(p)

# Make grid with plot and image
cow_file <- system.file("extdata", "cow.jpg", package = "cowplot")
p2 <- ggdraw() + draw_image(cow_file, scale = 0.9)
plot_grid(
  p + theme(legend.position = c(1, 1), legend.justification = c(1, 1)),
  p2,
  labels = "AUTO"
)

# Manipulate images and draw in plot coordinates
if (requireNamespace("magick", quietly = TRUE)){
  img <- magick::image_transparent(
    magick::image_read(logo_file),
    color = "white"
  )
  img2 <- magick::image_negate(img)
  ggplot(data.frame(x = 1:3, y = 1:3), aes(x, y)) +
    geom_point(size = 3) +
    geom_abline(slope = 1, intercept = 0, linetype = 2, color = "blue") +
    draw_image(img , x = 1, y = 1, scale = .9) +
    draw_image(img2, x = 2, y = 2, scale = .9)
}

cowplot

Streamlined Plot Theme and Plot Annotations for 'ggplot2'

v1.1.1

GPL-2

Authors

Claus O. Wilke [aut, cre] (<https://orcid.org/0000-0002-7470-9261>)

Initial release