local_image
Helper function for adding a local image
Description
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 that the
text_transform() function is used. 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.
Usage
local_image(filename, height = 30)
Arguments
filename |
A path to an image file. |
height |
The absolute height (px) of the image in the table cell. |
Details
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 cid=<random CID> 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.
Value
A character object with an HTML fragment that can be placed inside of a cell.
Figures
Function ID
8-2
See Also
Other Image Addition Functions:
ggplot_image(),
test_image(),
web_image()
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 the
# `text_transform()` function to insert
# a local test image (PNG) image with the
# various sizes
tab_1 <-
dplyr::tibble(
pixels = px(seq(10, 35, 5)),
image = seq(10, 35, 5)
) %>%
gt() %>%
text_transform(
locations = cells_body(vars(image)),
fn = function(x) {
local_image(
filename = test_image(type = "png"),
height = as.numeric(x)
)
}
)