A ggplot extension for drawing smooth non-convex irregular hulls around groups of points, which can fit the shape of boundaries perfectly!
ggunchull can be installed from github.
devtools::install_github("sajuukLyu/ggunchull", type = "source")Take a pancreas dataset for example:
library(ggplot2)
library(ggunchull)
data("pancExample")
plotData <- pancExample
# setup a proper distance to extend (and simplify) the circle (here use 3% of the range of x axis)
delta_r <- 0.03
th_r <- 0.03
delta <- diff(range(plotData$UMAP_1)) * delta_r
th <- diff(range(plotData$UMAP_1)) * th_r
ggplot(plotData, aes(x = UMAP_1, y = UMAP_2)) +
geom_point(aes(color = celltype), size = 0.3, shape = 16) +
stat_unchull(aes(color = celltype, fill = celltype), alpha = 0.3, n = 5, delta = delta, th = th) +
theme(
aspect.ratio = 1,
panel.background = element_blank(),
panel.grid = element_blank(),
axis.line = element_line()
)
The detailed algorithm will be explained later soon... (when I have free time)