Highlight a Specific Section of a Treemap using Treemap package in R - r

Question

I am using the Treemap package in R to highlight the number of COVID outbreaks in different settings. I am making a number of different reports using R Markdown. Each one describes a different type of settings and I would like to highlight that setting in the treemap for each report, showing what proportion of total outbreaks occur in the setting in question. For example you I am currently working on the K-12 school report and would like to highlight the box representing that category in the figure.
I was previously using an exploded donut pie chart however there were two many subcategories and the graph became hard to read.
I am picturing a way to change the label or border on one specific box, ie. put a yellow border around the box or make the label yellow. I found a way to do both these things for all the boxes but not just one specific box. I made this image using the snipping tool to further illustrate what the desired outcome might look like. The code to generate the treemap can be found in the link below. It looks like this:
# library
library(treemap)
# Build Dataset
group <- c(rep("group-1",4),rep("group-2",2),rep("group-3",3))
subgroup <- paste("subgroup" , c(1,2,3,4,1,2,1,2,3), sep="-")
value <- c(13,5,22,12,11,7,3,1,23)
data <- data.frame(group,subgroup,value)
# treemap
treemap(data,
index=c("group","subgroup"),
vSize="value",
type="index"
)
This is the most straightforward information I can find about the package, this is where I took the sample image and code from: https://www.r-graph-gallery.com/236-custom-your-treemap.html

Answer 1

It looks like the treemap package doesn't have a built-in way to do this. But we can hack it by using the data frame returned by treemap() and adding a rectangle to the appropriate viewport.
# Plot the treemap and save the data used for plotting.
t = treemap(data,
index = c("group", "subgroup"),
vSize = "value",
type = "index"
)
# Add a rectangle around subgroup-2.
library(grid)
library(dplyr)
with(
# t$tm is a data frame with one row per rectangle. Filter to the group we
# want to highlight.
t$tm %>%
filter(group == "group-1",
subgroup == "subgroup-2"),
{
# Use grid.rect to add a rectangle on top of the treemap.
grid.rect(x = x0 + (w / 2),
y = y0 + (h / 2),
width = w,
height = h,
gp = gpar(col = "yellow", fill = NA, lwd = 4),
vp = "data")
}
)