We can flexibly add a local image (i.e., an image residing on disk) inside of
a table with local_image() function. The function provides a convenient way
to generate an HTML fragment using an on-disk PNG or SVG. Because this
function is currently HTML-based, it is only useful for HTML table output. To
use this function inside of data cells, it is recommended to use
text_transform() first. With that function, we can specify which data cells
to target and then include a local_image() call within the required
user-defined function (for the fn argument). If we want to include an image
in other places (e.g., in the header, within footnote text, etc.) we need to
use local_image() within the html() helper function.
By itself, the function creates an HTML image tag with an image URI embedded
within. We can easily experiment with a local PNG or SVG image that's
available in the gt package using the test_image() function. Using
that, the call local_image(file = test_image(type = "png")) evaluates to:
<img src=<data URI> style=\"height:30px;\">
where a height of 30px is a default height chosen to work well within the
heights of most table rows.
Examples
Create a tibble that contains heights of an image in pixels (one column as a
string, the other as numerical values), then, create a gt table. Use
text_transform() to insert a local test image (PNG) image with the various
sizes.
dplyr::tibble(
pixels = px(seq(10, 35, 5)),
image = seq(10, 35, 5)
) |>
gt() |>
text_transform(
locations = cells_body(columns = image),
fn = function(x) {
local_image(
filename = test_image(type = "png"),
height = as.numeric(x)
)
}
)
See also
Other image addition functions:
ggplot_image(),
test_image(),
web_image()