Easily add a logo to a ggplot

This function wraps around a few functions from cowplot and magick to add a logo (or other annotation) to the bottom of a ggplot plot, an otherwise tedious and easy to forget process. It's meant to be flexible in the types of objects it can place; as a result, it's less flexible in their placement and customization. For more specific needs, the source of this function should be easy to build upon.

add_logo(
  plot,
  image = NULL,
  position = c("right", "left"),
  height = 0.05,
  place_inside = TRUE,
  ...
)

Arguments

plot: A ggplot object onto which the logo will be placed.
image: Either a string giving the path or URL to an image file to be read by magick::image_read; the results of reading a file or manipulating an image already with magick::image_read or other magick functions; a ggplot object / grob; some other object that can be handled by cowplot::draw_image; or NULL, the default. If NULL, the image will come from the file at system.file("extdata/logo.svg", package = "cwi"). As built, this is a logo for DataHaven, but that file can be replaced for repackaging this library for other organizations or projects.
position: String, either "left" or "right", giving the side on which the logo should be aligned. Default: "right"
height: Numeric: the height of the logo, as a percentage of the height of the image given in plot. Adjust as necessary based on the dimensions of the logo. Default: 0.05
place_inside: Logical: if TRUE (default), logo will be drawn within the plotting area; otherwise, an additional grob is built below the plot, meaning the logo could later be cropped away, which may be undesirable.
...: Additional arguments passed to cowplot::draw_grob if attaching a grob, or to cowplot::draw_image otherwise.

Value

A ggplot object.

Examples

if(interactive()){
  p <- ggplot2::ggplot(iris, ggplot2::aes(x = Sepal.Length)) +
     ggplot2::geom_density() +
       ggplot2::labs(title = "Test chart", caption = "Source: 2019 ACS 5-year estimates")

     add_logo(p)
     add_logo(p, magick::image_read(system.file("extdata/25th_logo.png", package = "cwi")),
     height = 0.1)

     # This example logo is not all that attractive, but shows how you might
     # attach a ggplot grob as a dynamically-created logo
     dummy_data <- data.frame(town = letters[1:4],
                              pop = c(21000, 40000, 81000, 36000))

     gg_logo <- ggplot2::ggplot(dummy_data, ggplot2::aes(x = town, y = pop)) +
       ggplot2::geom_col(width = 0.8, fill = "skyblue") +
       ggplot2::annotate(geom = "text", label = "DataHaven", x = 0.6, y = 6e4, hjust = 0,
                         family = "mono", size = 5) +
       ggplot2::theme_void()

     add_logo(p, gg_logo, width = 0.2, height = 0.1)
  }

Arguments

Value

See also

Examples