(This article was first published on

**R on G. Yu**, and kindly contributed to R-bloggers)I implemented a function, *subview*, in

ggtree

that make it easy to embed a subplot in ggplot.

An example is shown below:

```
library(ggplot2)
library(ggtree)
dd <- data.frame(x=LETTERS[1:3], y=1:3)
pie <- ggplot(dd, aes(x=1, y, fill=x)) +
geom_bar(stat="identity", width=1) +
coord_polar(theta="y") + theme_tree() +
xlab(NULL) + ylab(NULL) +
theme_transparent()
x <- sample(2:9)
y <- sample(2:9)
width <- sample(seq(0.05, 0.15, length.out=length(x)))
height <- width
p <- ggplot(data=data.frame(x=c(0, 10), y=c(0, 10)), aes(x, y))+geom_blank()
print(p)
for (i in seq_along(x)) {
p %<>% subview(pie, x[i], y[i], width[i], height[i])
print(p)
}
```

With this function, we can plot a specific clade and add a subplot of

the whole topology; we can also add relative statistic graph above the

tree or to a specific node. It’s not specific to phylogenetic tree, it

works with all ggplot objects as demonstrated in the example.

PS: ggtree is now

presented in CRAN Task View:

Phylogenetics.

AND get its first citation.

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