```r
bb = st_bbox(st_union(x, y))
box = st_as_sfc(bb)
set.seed(2017)
p = st_sample(x = box, size = 10)
plot(box)
plot(x, add = TRUE)
plot(y, add = TRUE)
plot(p, add = TRUE)
text(x = c(-0.5, 1.5), y = 1, labels = c("x", "y"))
```

<div class="figure" style="text-align: center">
<img src="figures/venn-subset-1.png" alt="Randomly distributed points within the bounding box enclosing circles x and y." width="50%" />
<p class="caption">(\#fig:venn-subset)Randomly distributed points within the bounding box enclosing circles x and y.</p>
</div>